Comparison Test: Are Wider Rims Better? We Try 4 Different Widths

Jul 12, 2018
by Matt Wragg  



I still remember the corner clearly. Dropping off the lift, you pick up the narrow, rocky trail down to the grass. Mud soon replaces rock underfoot and the tyres start biting. The corner itself is just a flat, grassy bend as you traverse from one side of the resort to the other. Leaning into that first corner something unexpected happened. As I started to lay the bike over the tyres held, digging into the dirt and I could push the bar closer and closer to the ground. That's the magic - one of those perfect moments when the bike and the trail seem made for each other, when you feel like a hero, if only for a split second.


2015
The corner. I'm certain I was getting lower when there was no camera...


That was my first corner on wide rims. Nothing else in my setup changed - same bike, same tyres. My 25mm internal width wheels had been replaced by burly-looking Ibis 741s with a full 35mm internal width that my wife had left over from her race season.

Through the rest of the day, I giggled my way up and down the bike park in Roubion, pushing the bike in a little harder each time, trying to get closer to the limits of grip. For me that was it, I was sold. In fact, since that day in 2015, I have switched all my bikes over to wide profile rims. They felt good, so I haven't built a bike with rims less than 30mm wide since.
Wider rims better support the tire s side wall.
Syntace's graphic depicting the wider rim's stabilizing effect upon the tire profile holds the record for the most poached image on the subject.

There's one problem with this: it was a flawed decision. If I'm honest, that decision was almost entirely based on feelings from that single corner. Over the years since, I have covered a few thousand kilometers on 35mm rims, and I can confidently say that I like them when they are paired to the right tire (I have been running 2.35 Schwalbes pretty religiously). But, if you stopped me and asked why, I couldn't really give you a much better answer than how good they felt in that one corner.


Rim Width: Separating Feelings VS Facts

Back in 2015, anything over 30mm was fairly extreme, but today it is generally accepted that wider rims are better. But, if we get down to the fine detail, how exactly does a 30mm or 35mm rim feel better than a 25mm rim? Aside from every manufacturer's press release claiming that their rim offers the perfect balance, what does it actually mean out on the trail? Is it better in every situation? Are there drawbacks? How wide is too wide? Or, did I just get carried away and I've been getting it wrong all along? To be sure, I had to separate my feelings from the facts, and the best method to accomplish that is a side-by-side comparison.

DT Swiss XM 1501 rim profiles

bigquotesDT Swiss XM 1501 wheels have the same hubs, the same spokes, the same spoke counts and the same intended application. In other words, this is about as close to a neutral test as anybody without their own extrusion facility is likely to get.

Choosing the Wheels

To try and break down the benefits and drawbacks of rim width it's not as simple as picking rims based solely on width - after all, comparing a 30mm DH rim to a 25mm XC rim or a 40mm "Plus" trail bike rim, is like trying to compare apples and oranges. The weight of the rim will be vastly different between the two, as will stiffness and strength. The same goes for comparisons between different manufacturers. For this test to work, it would need a single manufacturer that produces a range of widths for a single application.

Enter DT Swiss and their XM1501 wheels. They produce XM1501 wheelsets in a range of widths that span from 25mm to 40mm, in 5mm increments, something I do not think any other manufacturer offers. They have the same hubs, the same spokes, the same spoke counts and the same intended application. In other words, this is about as close to a neutral test as anybody without their own extrusion facility is likely to get. So, DT shipped me a pair in 25mm, a pair in 30mm and a pair in 35mm. The original plan was to receive a pair in 40mm too, but it was only available as a front wheel, so for the test, I would run it in combination with the 35mm rear wheel.
XM 1501 wheel

About the Test Bike

With the wheels sorted, the next question would be the test bike. Originally I had hoped to use one of my personal bikes as the testing bike. However, what I failed to check is diameters on the DT Swiss website. While they do make the XM1501 in 29, they only offer them in 25mm and 30mm widths, which is not really a big enough range to get usable information from. That meant for the test I would need something with 27.5 wheels, while all my personal bikes (except my DH bike) run on 29.

Rim width test. Photo by Matt Wragg
I chose the Whyte T-130 for the review, which ticked all of the boxes for handling and all-mountain performance.

My criteria for the test bike were fairly strict. I wanted a short travel bike, partly because I like short travel bikes, but mainly because I believe that without the extra suspension, the tyre performance is a much bigger part of the overall feel on the trail. This would mean that I could focus on the wheels much more clearly. After that, I needed something that came off the peg with a fairly sturdy build and had a reach of somewhere between 450 and 475mm (if you're curious as to how I reached those values, check out my piece on how I believe reach should be proportional to body size). After much hunting, I found the Whyte T-130, which ticked pretty much all the boxes. It has a pretty solid reputation among bike testers as a hell of a lot of fun to spend time on. Whyte sent the RS build in large with a few small tweaks to the spec - a slightly higher rise bar and shorter stem, plus they stuffed the suspension full of tokens and bands as I like my bike to have quite a lot of ramp-up at the end of the stroke.


And, the Tires

The final piece of the puzzle was the tyres. This was an easy decision for me as I tend to run one combination of tyres all year round - a Schwalbe Magic Mary 2.35 on the front, paired with a 2.35 Rock Razor on the rear. I opted for both front and rear in the intermediate Snakeskin casing, as this is what I run on my trail bike, and I know it strikes a good balance between weight and security for me, providing I keep the pressures sensible (I weigh 70kg and run 23psi front, 28psi rear). Also, using a familiar combination meant that there would be no need for an adjustment period for me - I know very well how these tyres should perform in any given situation.
The profile of the Magic Mary
Schwalbe Magic Mary 2.35" tires are tough to beat for consistent grip.


Riding Conditions

For the first test, I headed to La Mouliere bike park. My original plan was to shuttle one of my local trails, but who can resist an early season chairlift? While it may be lift-accessed riding, La Mouliere is not a bike park in the style of Whistler - it is more like a collection of fairly natural, rocky trails tied together with the lift. I knew that it would put me close to or past the edge of where I am comfortable riding a short-travel bike, which is exactly what I was looking for to test the tires - trails where I needed every advantage I could get.

Rim Width story


Width VS Weight

Before I started testing, I wanted to first measure and weigh the wheels. First of all, I weighed each of the front wheels. Each rim was taped for tubeless from the factory, which may account for a small part of the weight discrepancies, but overall the claimed weights are pretty close to the real weights. The only difference between each of the wheels is the rim and each rim is made from the same grade aluminium to provide a uniform level of strength and stiffness. So what should we take from this?

Rim Width

25mm
30mm
35mm
40mm
Claimed Weight

736g
786g
840g
890g
Real Weight

743g
799g
830g
914g

Rim width test. Photo by Matt Wragg

Rim width test. Photo by Matt Wragg
Rim width test. Photo by Matt Wragg

Rim width test. Photo by Matt Wragg

If we take the 25mm wheel as the baseline, the additional weight (50g or so, going up to 30mm) is fairly negligible and you'd have to be a fairly committed weight weeny to care about that too much. Stepping up to 35mm gets to around the 100g mark, which you would feel out on the trail, so there would need to be a real advantage to justify the extra weight. At nearly 150g additional weight, and nearly a 100g step compared to 35mm, 40mm rims would need to be really good to be worth it.

Speaking to a product manager at a rim maker, he explained that as the rim gets wider, it is harder and harder to maintain strength as the edge gets farther away from the rim bed. This suggests that, for aluminium, we are somewhere close to the limit for width vs strength vs weight compromises.

This is where carbon starts to make more sense from a material perspective. As Ibis has shown with their 741/941 and 742/942 rims. At 25mm widths, the weight advantage of a strong carbon rim is not that great, but for these wider profiles, they start to make much more sense, creating rims at weights that are not currently possible with today's aluminium technology.
Weight differences are minimal because only the thin-wall sections of the rim are elongated to widen the rim profile.
Only the thin-wall sections of the rim are elongated to widen the rim profile, which minimizes the weight increase. But, the difference between a 25mm and a 40mm aluminum rim was still 171 grams.


How Rim-Width Affects Tire Profile

Next up are tire dimensions. The front wheels were mounted with a 2.35" Magic Mary tire and inflated to 30psi, using a Schwalbe digital pressure gauge. One measurement was taken edge-to-edge at the widest point of the tread, the other measurement was of the casing at its widest point.

Rim

25mm
30mm
35mm
40mm
Pressure

30.3psi
30.2psi
30.3psi
30.3psi
Casing Width

60.4mm
61.5mm
65.2mm
65.5mm
Tread Width

58.9mm
59.0mm
60.5mm
59.1mm

What is immediately clear, is that the tread-width is more or less constant and any variation within those numbers could be explained by production variances. It is the tread profile and the volume of the casing that changes as the rim's width increases. Inflating the tires in ascending order with a regular pump, it was noticeable how much more air it took to inflate the tire on the wider rims. The most significant measurement here is that the 40mm rim appears to offer little additional volume compared to the 35mm rim, indicating that the 40mm width is either at or past the limit of a 2.35" tire - which is what I expected in this case.

Note that the tread of the same 2.35 tire flattens out but remains about the same width while the casing grows from 56mm to 62mm as the rim grows from 22.5 to 40mm..
This graphic from the DT Swiss website shows that the tread of the same 2.35" tire flattens out, but remains about the same width, while the casing expands from 56mm to 62mm as the rim grows from 22.5 to 40mm.


Rim width test. Photo by Matt Wragg

Rim width test. Photo by Matt Wragg
Rim width test. Photo by Matt Wragg

Rim width test. Photo by Matt Wragg
The four widths 25-40mm, clockwise from the top left. It is hard to really show the curvature of the carcass in a photo like this, but hopefully you can start to see the effects of the wider rims.

So, what about the height of the tire? A quick comparison shows that rim width does not significantly affect the overall height of the tire when mounted. I found only a few millimeters difference between the 25mm rim combination and the 40mm rim combination - which could be explained by production variance and it does not appear to be significant enough to have any impact when riding.




bigquotesFor the third run, the times show that I had settled into a consistent pace and had slowed noticeably on the narrower rim - 7 seconds on a 3 minute downhill is notable...

The plan for riding was to start by doing two runs on each width, progressing from narrowest to widest. The idea being, to see a gradual progression through the widths. Taking some advice from the lift attendant, I chose the blue run (imaginatively called "La Bleue") for my testing - it has very little woodwork and no features I wouldn't fancy hitting on a little bike, but offers more challenge than the green runs.

With low clouds hanging over the station most of the day, the trails were in pretty prime condition - a little slippery in the morning from the humidity. For each run, I tried to ride at a consistent pace, not easing off too much, but not pushing too hard either. Partly, because the bike felt very close to the edge and I didn't want to crash and lose a day of testing and partly, so I could see if I could put as much of the difference as possible down to the rim width. Each time I mounted each set of wheels to the bike, I checked the tire pressures with a Schwalbe pressure gauge to ensure the front was always at 23psi and the rear, at 28psi (with a margin of variation of +/-0.3psi).

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Discounting the 40mm Width

Before we get into the meat of the comparison, we need to get the 40mm rim out of the way. Its inclusion was primarily to provide an example of where rim width went too far and it did just that. The volume of the tire made for a pleasant ride, but it was hard to feel any benefit in comparison to the 35mm rim. The flatter angle of the edging tread was very apparent - providing much less grip, and the tire had no bite when I tried to lean in on it. Factor in that the 40mm rim weighs about 100g more than the 35mm rim and it provides a very clear marker that there comes a point where going wider starts to detract from the performance with a given tire. After a single run, it was very apparent that the 40mm was not worth investigating further.


Establishing the Order

For the first two runs of the day, I ran with the 25mm rim, then two runs on the 30mm, then two on 35mm (and one on the 40mm as per above). Once I had finished a full set, I returned to the 25mm to verify if the performance changes of the increased rim widths were due to the track drying slightly and learning the lines. I then alternated between the 30mm and the 35mm rims for the afternoon to try and validate which I preferred and why.

25mm Report: The 25mm rim made the overall rear tyre profile feel very round - that its footprint did not have a stable connection with the ground beneath. That meant that when it was hunting for grip on rock or roots it always felt a little skittish like it wanted to slip out from under you. Laying the bike on its side the feel was not positive, it found some grip, but was a little indistinct and never felt safe enough to push in on. This feel tallies up with the side profile of the carcass - it has something of a bell shape to the sidewall, which allows for a higher level of deformation at the tyre is compressed, giving a vague feel when you leant on the side of the tyre.

Rim width testing. Photo by Matt Wragg


30mm Report: Moving up to the 30mm rim, the bike immediately felt more stable, more composed. The best way to describe the change is that the contact patch felt much flatter and with a much more positive connection to the ground, there was a definite feeling that it was trying to slide away less often. On the roots and rocks, this translated to a more planted feel that meant you could push a little harder than before. It is not a huge difference, but it is certainly noticeable. The combination of the straighter sidewall profile, that is less prone to deformation, and the sharp, outwards angles of the side tread, meant that when you wanted to dig the side into the dirt, it provided a very definite, positive feel that translated into more confidence to turn the bike hard. On one of the long off-cambers, you could tip the bike onto the side tread and hold a noticeable tighter line than on the 25mm rim.

35mm Report: The next step was the 35mm rim. The difference in terms of contact patch was less pronounced compared to the jump between 25mm and 30mm, it is a much more subtle difference. It felt a little more stable again and made it easier to push harder still, but it was subtle. You could feel that change, but the profile of the sidewall is still pretty straight, so despite the loss of outright bite there was still a very positive feel to the combination, it offered maybe the best support/contact patch of the test. There was some small trade-off in the side tread, the outer tread profile was less pronounced than the 30mm and on the off-cambers I had to back off slightly compared to the 30mm combination, but less so than on 25mm.


The Clock Doesn't Lie

I did not put too much emphasis on the timing. In such a small scope of testing, the numbers are always going to be somewhat unreliable, but a quick scan of the results is interesting:


The most interesting time here is the third run on the 25mm rim. Through the morning the times got faster, so it is easy to discount my first runs on the 25mm rim as getting up to speed, but for the third run, the times show that I had settled into a consistent pace and had slowed noticeably on the narrower rim - 7 seconds faster than my best time on a 3 minute downhill is notable - more so when taken in conjunction with my riding impressions, that the 25mm rim was my least favourite of the lot. The other area worth noting is the consistency of times between the 30mm and 35mm rim - much of the conventional wisdom suggests that a 2.35 tire on a 35mm rim is a less than ideal combination, but in terms of times and feel, it is hard to separate the two - it follows that wisdom in losing some side bite, but the profile of the carcass is better.


Disclosures

Just so we are explicit here - this is not a definitive test. To assemble enough data to make clear statements, such as "Xmm is Y seconds slower than Zmm," we would need a much larger, more rigorous test, using multiple riders over a greater number of trial runs. This test was designed to give a little insight and hold the perceived wisdom that "wider rims are better" to some measurable scrutiny.

This test only looks at one tire and rim combination to keep the scope of the comparisons manageable. I have no doubt that throwing another type of tire into the mix would produce different results. For instance, is the fact that 35mm rim felt good because of the extra volume and the change in casing profile, or is it related to one specific Schwalbe tire? I cannot answer that for you. There may also be further performance benefits to be had from exploring tire pressures in conjunction with each rim width combination, but I kept the same pressures in the name of keeping things manageable.

Rim width testing. Photo by Matt Wragg

bigquotesWould I ever buy a narrower rim for my bikes again? Never.

The Verdict:

By this point, it should be fairly clear that I feel there is a real advantage in going for a wider rim, and that is based on three factors: carcass profile, tread profile and overall volume. As with most tests, I have come away from this effort with more questions than I started with. I would like to know more about the subtleties between 30mm and 35mm rims. They both felt good, but for slightly different reasons, and I would like to break those reasons down to fully understand the matter. For instance: is there a sweet spot between the two? For 2.35" Schwalbe tires, would changing the width to either 31mm or 33mm produce a measurable benefit?

Then there are the obvious questions about how generally applicable this all is. This is where we, as consumers, need more information from bike manufacturers. Surely every tyre should come with a recommended rim width? In terms of outright performance, it would be interesting to see more wheel/tire systems that are designed in combination to work together perfectly. Also, the 35mm rim makes me want to know if the conventional wisdom that you need a larger tire for a rim that wide is right. If the carcass and overall volume feel good, would it not be possible to re-work a 2.35 tyre's tread to suit?

Maxxis has started down this road with their excellent WT models and Mavic tried to produce systems as far back as 2012, but their combination of poor tyres and a super-skinny rims at the rear were not a winner. With weight as an ever-present concern for wheels, the 35mm rim is a little heavier compared to a 25 or 30mm rim, but the combination is still lighter than anything with a larger 2.5 or 2.6 tire. If we could realistically hope for advances in production technology to reduce even 20 to 30 grams from the rims in the coming years, then we would be looking at a combination that offers useful benefits, compared to what most of us are running now, with increased volume, improved tyre profile and reduced overall weight.

If your question is: "My current rims are narrower, should I upgrade them?" In honesty, I would have to say no. If you are used to riding your current rims, why worry? Unless you have the chance to ride wider rims, you'll never know their benefits. In terms of outright performance, good geometry, suspension, and brakes are always more important. But... would I ever buy a narrower rim for my bikes again? Never. When it is time for me to replace a rim, wheelset, or even a bike, then I will definitely prioritize a 30mm+ rim as one of the things I must have.







254 Comments

  • + 227
 Nice article, I really like that you try to be as objective as possible.

But I have one concern (professional deformation):
the test would be much more relevant if you did not know the rim width you are on,
we call it a blind test. I know in real world it is difficult to perform, you would need to
erase any information on the rim and someone else would have to set up the bike and
hand it over to you, etc.
But never underestimate the placebo effect. If you like wider rims, and you know you are on
them, chances are you will perform better.
  • + 34
 @powpowpow That would be interesting, but practically I don't have the resources to do a blind test like that, I'd also want more accurate timing if I did that.
  • + 21
 It would also be interesting based on rider weight. I'm 6'5 and weigh in at 106kg and don't hold back on the downs. Narrower rims result in a lot of tyre rolling that the smaller guys don't get (unless I run daft high pressures to stop it).
  • + 3
 @bigtim: that is a good point, we run different pressures in our suspension but riders of all sizes and weights use pretty much the same pressure range in their tyres. I’m the opposite end of the spectrum to you at 5’6” and 65Kg and I do suffer tyre roll with thin tyres but surely it can’t be near as bad as for somebody more your size.
  • + 18
 Thought the same thing. He already had it definitively in his mind that 30mm was best due to his prior experience and I don't see how one could divorce themselves from that thought process in the test when they know what they're on.
  • + 2
 @bigtim: You nailed it Tim. I'm 6'3, 101kg and I ride with guys in 60kg realm.
  • + 6
 I would have liked to see more than one run on the 25 after a warm up. I don't Take anything from the data but I appreciate your perspective on the difference you felt
  • + 5
 Last season I finally upgraded to Nox Teocali, 30ext / 26int.

When I got back on my old wheels Easton XC90 (19 internal) it was WHACK.

Shockingly different. For the worse.
  • + 22
 Confirmation bias can be a real bitch when testing anything...
  • + 2
 What he said
  • + 9
 @mattwragg: A buddy hands you the bike at the top of a run and you don't measure/feel/eyeball the rims. Random number generator in excel determines which order of rims you do.
  • + 2
 Also adding tire inserts like cushcore or procore give the tire way more support on narrow rims, so much be worth throwing some inserts into the testing mix too.
  • + 3
 @mattwragg: Definitely agree with the timing accuracy for another version of this test, which I think should be blind and use multiple riders. The blind test will hopefully remove as much implicit bias as possible, but seems like more of an investment to pull off. We readers can only assume the Mfg companies like DT are doing mad tests like this, but none of it is exposed to us. We get the marketers input instead, which sounds annoyingly consistent from each bike company.

Also, for a more accurate compare, in my opinion, you should consider excluding results from the morning as the track consistency was changing and you were becoming familiar with the run, as evident in your afternoon lap on the 25mm. None of these results are statistically significant, but I really appreciate your approach and detailed analysis. Please keep doing these.
  • - 7
flag drivereight (Jul 12, 2018 at 8:57) (Below Threshold)
 Rim width does not matter. Air pressure, tire size, tire sidewalls and riders learning how to corner properly.
  • + 4
 Id love to see the test expanded outside the bike park, wonder if 25 would end up on top. Good stuff
  • + 6
 @mattwragg: The thing with grip in corners is that it's as much dependent on state of mind as it is on tire. I find that when I'm riding tentatively, not committing to loading up the front wheel in a turn on sketchy low-traction/off-camber corners, I wash out a ton more than I do when I'm feeling confident and pushing hard. So that experience you had with a wide rim first time you tried it - that was a huge confidence booster, and you were probably willing to commit more. Which means blind testing is completely impossible - so much depends on the wetware between the ears.

I'd say your setup for this was informative, and you were pretty clear about the methodology (and its limitations). Good on ya, and a good read.
  • + 4
 @bigtim: I'm in the same boat, when switching to wider rims I noticed I could run less pressure and not worry about rolling tires.
  • + 1
 @bigtim: For sure - I used to have a lot of burping from my back wheel when I was on narrower rims. Same weight as you, roughly - there are big differences in how different sized riders load things up.
  • + 7
 @mattwragg: I agree with powpowpow without a blind test this has the potential of being very biased. Notice how in your conclusions you recommend 30+ rims even if you have no evidence that 35 mm is better than 30.

Similar bias seems to show up in the analysis of the timed runs. You exclude data points after looking at the results instead of relying on an independent analysis. And cherry pick the largest observed difference to make your point, something a statistician would never do ...

Having said that, great effort!
  • + 4
 It's a good effort. Unfortunately as you stated without A LOT more trials the data is worthless. And as OP says the placebo effect rules all, the difference of rim width is going to be magnitudes less important than the placebo effect.

Instead of timing the whole run, perhaps you should time very specific sections? This reduces the variables and error. For example time an uphill section, downhill, berm, rocky uphill, rocky downhill, etc... Take the same line every time. Record the watts used through the timed section and entrance speed, then calibrate the times on how many watts and your entrance speed. Try to keep the same body position and effort through the timed sections. Consult a statistician for how many trials you will need (it depends on the variability of times).
  • + 4
 @drivereight:

but the bikerwebs told me wider is better... who the hell are you to challenge the new status quo?

everybody knows you can't have fun, roll with the endurobros, or win races on a "normalish" setup like EX471s (i25) and 2.4s!

#gwinning
  • + 1
 @shedsidechuck: Read bigtim's comment. I agree that different pressures and widths may be needed for different rider weights. Okie-dokie?
  • + 0
 Im just impressed how clever and well said is your comment !
  • + 8
 Well, I tried the blind test but I crashed in the first corner cause I couldn't see a thing...
  • + 1
 @duzzi: True. But what i think matters most is the tires themselves. Im still on 20mm internals and thats considered to be stupidly narrow nowadays. thing is. ive never been on anything wider so i dont really know what im missing. Ive got grip for days and no punctures lately.

But i would agree that if a bike feels more stable or more sure footed it gives you confidence to go faster. thus better times. but hey my stock wheels have crappy spoke nipples that break and frustrate me and bad seals around the bearings. Maybe if i order new ones ill go for something wider. But 35-40mm seems excessive to me.
  • + 1
 @mattwragg:
It's great to read and spot on!
Despite that i think you actualy missed by tring to be as true as possible, and maintaining "lab like" wheel conditions with the same presure.
I would very much rather understand what rim width would be best with your preferred settings for each width.
Conditions that will make rim use for a tester as close to "best" as possible.
After testing in these conditions, a conclusion would be more true and usefull for the masses.
thanks.
  • + 1
 @mattwragg: I know this would require more logistics, and I did not intend to take any credit off of your work.
But at a larger scale, Pinkbike could encourage its testers to get together and with proper planning these tests would be much more relevant.
  • + 72
 Really good comparison. I'm curious as to why you see so many pro racers, both in DH and Enduro, still running DT swiss EX471s? They have an internal width of 25mm. I have them on my DH bike and really like them too.
  • + 50
 Yeah,pro riders,man. What do they know!
  • + 19
 Because they’re using proper tyres. You don’t need wide rims if you use appropriate tyres. If we stop using xc tyres we can use normal rims that don’t square off your tyres.
  • + 6
 @scottay2hottay The whole subject of what the pros run and why is a can of worms that I don't really want to get into right now. The short version is that what they need from their bikes to compete is a long way divorced from what you or I run, and is more about confidence and feeling, rather than what is objectively 'better'. A top of the food chain WC rider would most likely have a better run on a shitty bike that they feel completely at home on, than on the best bike in the world if it feels off for them. It's more nuanced than that, but that is a starting point...
  • + 3
 @mattwragg: Makes sense, thanks for the response.
  • - 4
flag ka-brap (Jul 12, 2018 at 1:44) (Below Threshold)
 One of the benefits of the narrower rim is that the tire profile is more "light bulb" shaped rather than squared off and this can prevent pinch flats a little better. This could be why lots of pros are running this rim width given all of the flats we've seen ruin race runs.
  • + 4
 @ka-brap: At least at normal, human speeds I'm not convinced of this argument. I didn't notice any difference in how often I flatted when I went to wider rims. Maybe for elite racers it is different.
  • + 3
 @scottay2hottay I get on fine with my spank 28's which allegedly have a 22.5 internal width. not about to drop a huge amount of cash just for an incremental gain. maybe when i blow these wheels up?
  • + 5
 I like to think the strength vs weight factor would be a factor there. EX471's are known for being pretty bomb proof, so why risk something wider and heavier that may not stand up as well to the abuse of a DH run.
  • + 6
 @iian: Brook Macdonald is/was on the EX511s this season...
  • + 2
 @mattwragg:
Think this does a better job of explaining the ideal relationship between tyre size and rim width.

And as someone else said (in coarse terms and down voted into oblivion), bigger tyres for wider rims.

www.notubes.com/technology/wide-right
  • + 1
 @mattwragg: New rim dilemma solved, thanks - was swithering between 471 & 511
  • + 7
 @mattwragg: Not to add fuel to the fire, but Laurie Greenland downsized to the 471s given they offer a bit more compliance than their bigger brothers. Again, as you stated, pros are in their own world. I still remember a couple of seasons ago when the Santa Cruz team was building their Enves with butted spokes not completely tensioned to add some compliance into the wheels, in order to avoid being whacked out of line by the stiffer rims.
  • + 5
 And I have the same tyres as tested in 26" on my HT with 23mm ID Flows. To say there is grip for days would be an understatement. Far more user friendly than my other bike with 2.6 tyres on 30mm rims which are crazy pressure sensitive. .
  • + 7
 the ex471's are bomb proof
  • + 0
 @southoftheborder: There should be no difference in compliance in the rim going from 471 to 511, so that must be in the tyre - which while not quite the same thing, fits with what I found here. You have to consider the whole system - I don't know how stiff that Summum is, but the 40 on the front of it is super-stiff, so in that context it makes sense searching for some more give, especially for a lighter rider. To draw a parallel, on my ebike which has a very stiff mainframe, I went from a 36 with Ibis 741s (both very stiff) to a Selva with DT EX581s (both less stiff) and the difference in overall compliance was significant, I could feel the extra traction very clearly. In Laurie's case I would imagine there aren't many variables for him to change as he has to ride that frame and fork, and I doubt a WC rider would risk a lighter rim (the 471 is already light for WC DH), so that leaves the tyre.
  • + 1
 @mattwragg: Racers often switch between the 2 depending on the track, do they not?
  • - 7
flag endurocat (Jul 12, 2018 at 5:38) (Below Threshold)
 It just proves how stupid this test really is.
  • + 9
 @mattwragg: I'm not sure why you think the 471 and 511 should have identical stiffness? The latter is wider and heavier, and the extra width will give it a greater second moment of area in resisting lateral deflection.
  • + 1
 @threehats: Because that is how DT design their range - in much the same way that the XM wheels I tested all had very similar levels of stiffness/compliance/strength, the EX511 and EX471 are intended to be parallel products, for the same application, tested to the same extremes, etc.
  • + 2
 @mattwragg: Sorry about the poor wording, I hate writing in my phone as it drives me to over-simplifying my statements. I wasn't stating the change to a narrower/lighter rim would improve the compliance by itself, but in the context of the wheel as a whole, tire and spokes included. Hence my other example of the Enves with not ultra-tightened butted spokes. As you said, sponsors dictate your actual available choices at the WC level (I still have to see a team sponsored by Sharpie, but I'm digressing), but I still find significance in Laurie's downsizing for the very reasons you address in your answer.
  • + 0
 @southoftheborder: I think we're pretty much in agreement here, but getting the words all wrong. Also, it helped me to work through the situation like that, to try and understand it...
  • + 3
 @headshot: Agreed. I'm on 2.6 Maxxis with 19 mm rims, ZERO concerns about traction. Entire tyre has 'give' not deformation but it's a different way to get traction and grip when the entire tire in contact can move a little.

Like long top tubes, wide rims are nothing new. Stuff was around in the 90's.
  • + 0
 @mattwragg: if some pros are running 471s it’s because they like them more than the 511. Does that make not make them “objectively better” to them?
  • + 3
 @mattwragg: Do you have anything to back up your statement "There should be no difference in compliance in the rim going from 471 to 511". I'm interested because a larger section rim will have a higher rim torsional stiffness, which results in more lateral stiffness.

Agreed tyre stiffness is a more dominant effect.
  • + 1
 @chakaping: 511 front 471 rear
  • + 2
 @phutphutend: Riding the XMs for this test I could not feel a difference between the different width rims and the EXs have been designed by the same team, with the same philosophy for the range. That's not to say there isn't a difference, but my experience with DT suggests it will be a small one, too small for me to pick up in this context, although that is not to say that someone at Laurie's level could not potentially make a far finer differentiation than I can.
  • + 17
 @splayleg: No, that is pretty much the definition of subjective.
  • + 5
 @mattwragg: at the end of the day racers are payed for their results not opinions. It sort of gets objective
  • + 2
 @Ktron: Agreed, Stan's wideright chart is the most accurate guideline for picking the right rim to tire widths. Atleast from my experience.
  • + 2
 @Ktron: Agree completely. A 2.3 maxxis is perfectly shaped, IMO, on a 25-27mm inner width rim and squares out too much on a 30mm rim. Schwalbe 2.35 have bigger carcasses than Maxxis and would do better on a bigger rim. It's the maxxis 2.5's that fit my 30mm rims perfectly. @mattwragg @Maxxis @schwalbe what are your thoughts?
  • + 1
 @mattwragg: I think compliance has a lot to do with rim depth. The shallower the rim, the more compliance it gives. Check out @Spank-Ind new Oozy 350 rim with a super shallow rim. spank-ind.com/products/oozy-350-rim
  • + 1
 @mattwragg: there was a write up about how Laurie went to 471 because they are softer and would suit Val di sole better vs the 511. Pretty sure it's on a vital slideshow.
  • + 2
 @mattwragg:

yeah but we want to open that can... time to start drafting up a follow-up article!

thanks for the article!
  • + 2
 @Ktron: That’s exactly what I was thinking. I like this type of semi-objective testing but 2.35” tires for all rim widths? I thought it was pretty well agreed-upon that anything north of 30mm rim width was getting a little wide for 2.35” tires.

I’d like to see a new test with different tire widths as well.
  • + 4
 @dbendixen: schwalbe 2.35 equals maxxis or specialized 2.5
  • + 2
 @dbendixen: My thoughts aswel, there are so many veriables for tire/rim set up now days. We are spoiled for choice. There is no ideal set up for everyone. In the ski world there are so many options for tip/tail/underfoot width. side cut profile, cambering, flex pattern, etc that offer a plethora of different experiences for a verity of conditions, terrains and skiing styles. Skiing is also less focused on time and more focused on overall enjoyment. There is no ideal set up for everyone, bikes are moving in this direction.
  • + 1
 @mattwragg: the shitty bike ex, it's for all. confidance on known equipment is underated
  • + 1
 @makripper: is there a link you can send me that shows measurements? I don’t think Spec has 2.5 tires. Their 2.6 tires come in at over 2.5 on a 30mm rim.
  • + 1
 @dbendixen: their DH tires are. Right they have the all mountain 2.6 and 2.3 now. I can measure when I'm home if u like. I actually have 2.6 on the DH bike and 2.3 on the am. Same size rims too. Waiting on some dhr2 DH tubeless 2.4 as well. Can also get sizing on that for u.
  • + 3
 Its the best width to avoid a pinch flat and still have great performance . When you do rim to tire your on thicker rubber. I normally run ex471s and love them. Got a great deal on a pair of industry nine with 30mm width and didn't like them because I pinch flated a new e thirteen lg1+ tire through a Cush core. All the damage on the cushcore was on the very outer edge where as with the ex471s is more into the meat of the cushcore
  • + 2
 So was Laurie Greenland and switched to ex471s for Val di sole@mattwragg:
  • + 1
 @Engie85: yes he did.
  • + 5
 Allways funny to see how sponsored Pinkbike never ever give a test where old tech beats new tech...
But the most used rim in DH and EWS is still the good old EX471...
Have it too .. with WT tires on it.. am I a sinner now?
  • - 4
flag makripper (Jul 14, 2018 at 14:18) (Below Threshold)
 @Trailstunter: not good for the average guy though. They are soft. A race weekend throw away rim. Still shows how sick it is. Gwin rode a DH track on just the rim and it held up
  • + 2
 @makripper: you talk a whole lot of BS...
  • - 2
 @Trailstunter: why do you say that? They sent and ding up easily because they are soft. Have you ridden them before??

Here's his race run for reference. Leogang 2014 on the 471
youtu.be/PUoCSzVmhhQ
  • - 1
 @Trailstunter: f autocorrect. Dent bahah
  • + 2
 @makripper: I weigh 100 kg's... and ride them for a year... no dent to find... they are not soft...
Looking at your youtube movie... there are no dents to spot in the rim... after the whole DH track... your story is BS...
  • - 4
flag makripper (Jul 17, 2018 at 5:07) (Below Threshold)
 @Trailstunter: wow you are slow. they are softer and more pliable than the 511 and yea i dented some to shit before. Your whole life is bs
  • - 4
flag makripper (Jul 17, 2018 at 5:09) (Below Threshold)
 @Trailstunter: oh right, and Laurie actually says that in an interview so he's full of bs too. It's on vital MTB about Val di sole this year. One of the pits bits or slide shows. Good luck lol you need all the help you can get
  • + 2
 @garrettstories: sorry we're just seeing this now, but wanted to let you know that you hit the nail on the head. If your preferred tire size is a 2.3, then there's really no benefit to going with a wider rim. Like you said, something in the 25ish mm range is perfect for that. Our WT offerings (2.4-2.6) do work best on 30-35mm rims.

If you're in the market for a new set of wheels AND you want to experiment with a variety of tire widths, it's hard to go wrong with 30-35mm. You can pretty much run anything from 2.3-2.8" wide (with varying degrees of success, of course).
  • + 2
 @Maxxis: thank you!
  • + 1
 @Maxxis: I'm running the DH tubeless dhr 2 2.4 Why is it labelled wt? It seems very similar in dimensions to the old DH tube version. That was misleading when trying to find new tires but once on and rolling they work great with my spank spike Evo 28 rims (28 external)

Cheers!
  • + 1
 @makripper: the DHR II being a more recent tread pattern was actually designed around wider rims to begin with. Basically, it predates the Wide Trail distinction. Same with the 29x2.5 Minion DHF. You'll see some that have the older hot patch that don't denote WT, but they are in fact WT. All of our newer treads in 2.4-2.6 widths are designed with wider rims in mind.
  • + 1
 @garrettstories: you're welcome!
  • + 42
 My wife keeps telling me wider is better. This'll show her....
  • - 7
flag mokydot (Jul 12, 2018 at 1:02) (Below Threshold)
 Something wrong in here.
  • - 16
flag ka81 (Jul 12, 2018 at 1:19) (Below Threshold)
 Show what?
In verdict it's about 30 & 35. So, you saying your wife need different sizes? )
  • + 29
 All that work. All that data. All that time. And you ran 2.35's.....tsk,tsk
  • + 11
 Agree. Should have at least thrown some 2.5s on!
  • + 30
 Right but that's a Schwalbe, fit wider than a bunch of other tires
  • + 1
 Yet there is a lot of variation between sizes depending on manufacturer. I've got 35mm rims front and rear and was running 2.6 Magic Mary front and 2.35 Rock Razor rear which both performed well. Now moved to Maxxis Reckon front, Ikon rear same sizes as the Schwalbes and tyre is no significant difference in tyre profile and performance. Never going back to narrow rims.
  • + 7
 My take is that he was riding the tires he was used to, to try and eliminate a variable. But yeah, 2.35's on a 40mm would have felt shit no doubt.
  • + 20
 2.35 Magic Mary = 2.5 Maxxis
  • + 10
 I'm running 29X2.35 Magic Marys on 30mm rims, they measure wider than a 2.4 DHR on a 35mm rim. In the case of this test, running tires he was familiar with makes sense.
  • + 5
 To me the Marys feel squared off on a 30mm rim compared to DHF2.5s, even though they are roughly the same width when mounted. Would love to see this same test with Maxxis WT
  • + 1
 Better to look at the true tyre width in mm, than the mythical imperial size. Magic Mary 2.35" is about the same size as a current Maxxis 2.5" (and much bigger than older Maxxis 2.5) and as big as some so-called 2.6" tyres too.

I'm still on 25.5mm rims and am running various 2.3", 2.4" and 2.5" WT Maxxis tyres. They're all a good shape on that width. The Minion SS 2.3 would definitely be too square on even a 30mm. The DHR2 2.4 WT is surprisingly square on the 25.5 rim and I wonder how it would be on the 35mm it's allegedly designed for? The DHF 2.5 WT and Shorty 2.5 WT would be squarer on a wider rim but they're certainly not too round on the narrower rim.
  • + 1
 @BT180: schwalbes 2.35 is to what most other brands 2.5 is.
  • + 3
 Before wt’s I would have agreed about the maxxis being undersized but I have measured with calipers my DHF/Aggressor/DHR 2.5 x 29 and they are right at 2.5.
  • + 1
 Actually Schwalbe is the correct size and it's Maxxis who is messing things up. 2.35 inch is about 60mm. Which is what is measured. I don't understand why Maxxis is doing this. It's like they don't understand their own imperial system. But if I remembered correctly Maxxis has adressed this issue recently but I'm not sure..
  • + 1
 Its just a joke, peeps
  • + 1
 My thoughts exactly.
  • + 2
 Funny enough Magic Mary compared to most other tyres like Minions DHF and DHR2 is a rather vague tyre on hard surface, very hard to press it in without spongy feel. It's almost like riding Shorties. Hard to talk about surefootedness of a particular rim width when knobs are folding over.
  • + 19
 Nice article, but it would have been a useful addition to include a paragraph about what the fast guys run.
From being at recent DH world cups, an EWS and the Megavalanche I'd have to say that the fast guys are not in line with your findings. Non-scientific observations seems to suggest that the top 10 guys all run rims of +/- around a 27mm average.
And pretty much all run either 2.35 Schwalbe or 2.4/2.5 Maxxis tyres. Absolutely none that I've seen race with 2.6 or bigger
  • + 7
 This. Problem is...there is WAY too much variance in rider level on a site like PB. when you're seeing 30second swings in times during a test like this, you know it isn't really worth much. Not to mention the tester knew which rim he was on...totally ridiculous from a scientific perspective.
  • + 2
 @nvranka: yeah that also occurred to me. Surely this test is biased by placebo effect - the tester unsurprisingly finds exactly what he was expecting to.

it could so easily have been a blind test with random wheels being used (installed my a separate person)
  • + 1
 @IllestT: I remember there being a video where rob warner and some current pros did blind wheel size time tests and posted results...I think even on different bikes (e.g AM vs DH, same track).

That'd be nice for this I guess.

Candidly I don't really care...my buddies and I have always ridden and raced what we liked, and when in doubt just followed suit with any top pro who we could relate to style wise. Not scientific, but has worked fine for me.

Never liked wide rims, but I run DH casings on all my bikes, so probably helps a lot with EXO
  • - 1
 @nvranka: even at a regional downhill race the top ten guys are within a couple of seconds. . . . . And No tire inserts? Come on! ! !

It’s hard to take any test or review that a journalist does seriously!
  • + 3
 @nvranka: Yeah I'm same really. See what the fast guys at races run and follow suit. It's steered me clear of quite a few crap fashions over the years. Remember when "slamming" the front end with flat DH bars was trendy? Another keyboard warrior's favourite, that no one actually-fast used, haha.

Plus-sized tyres are another
  • + 1
 @nvranka: more importantly a sample size of 10 runs is hardly a statistically sufficient sample.

But to your point of skill level, this kind of a test (if it yielded sound results) would be great for a website catering to riders of all levels. What tire/rim combination can help the average rider corner better and go faster with fewer flats?
  • + 12
 Great comparison, always wanted to read something like this. However, I'm afraid results are really tire dependent. I tried DHR2 in 2.3 on a 30mm rim and they had terrible cornering traction, probably because of the square shape.
  • + 4
 same, also the e13 has a brutally square profile on 30mm rims. if your on the edge corneringgrip is awesome but you have to dare to lean the bike that far without any transition. mm 2.35 works very well on 30mm rims
  • + 2
 Ditto, the 2.4WT is much better though and still feels very fast. 2.3 HR2 is simialr as is very squared off. 2.3 Aggressor OK on 30mm, where as 2.5 version feels maybe like needs slightly more than 30. A 30mm is spot on for 2.5 DHF. Massive caveat - my big heavy ass!
  • + 1
 Right. For awhile, Jeff Jones of Jones bikes proclaimed that a 50mm rim could run an Ardent 2.4 and he actually liked that combo. That was probably because the Ardent is fairly rounded profile and the fact that for touring that might have some benefits of lower rolling resistance. In my experience at least, tires with a more round profile, like the Nobby Nic, Rocket Ron, Ranger, Ikon, Ardent, Mezcal, etc do far better stretched than more aggressive treads with big cornering blocks, but you still need enough rim to adequately support the tire at lower pressures.
  • + 1
 @PHeller: I would agree on Ardents, they are far too rounded for even 25mm IMO. No doubt thats why the plus tyres have these much more rounded profiles like REKON etc.
  • + 1
 maxis is starting to make tires just for wider rims, theorically a "normal" HR dosent work properly for a 30 rim because it deforms the right profile
  • + 8
 As a born again MTBer back from pre 2000s. I was shocked that rims and tyres went thinner over a decade and a half. The OG were rocking 3.0 tyres on 50mm rims 'back in the day'. My ideal rear tyre would be a 40mm rim with a 2.8 low profile tyre. Front would be the same but higher profile and more curvature built into tyre designs, rather than curved by rim width.
  • + 19
 I dont think anyone misses 3" tyres from back in the day.
  • + 3
 @zyoungson: some big lads miss it.
  • + 3
 @zyoungson: except maybe all the people the "plus" industry is built around. 3" might be over kill but I'd run 2.7 or 2.8 if I could....
  • + 3
 @AntN: Always ran a 2.6 Kenda Talonix in winter on the front of my DJ bike. It's a lot wider than the Maxxis 2.7 and you can annihilate anything with that tire! Also, it looks really cool on a DJ3 2007 in all blak!
  • + 2
 Gazzaloddi's!
  • + 2
 @boxxerace: Impossible to find these! There is a dude in Bulgaria, I believe, who still has Monster Ts and Gazzas on a Big Hit...what else Big Grin
  • + 8
 I got myself some 30mm rims a few years ago when they started to appear again and they were ok. Didn’t really feel much of a difference, just made the bike look cool like a moto. So went up to 35mm and honestly hated it. Squared off tyres were draggy uphill and scary to corner with. I went back to a nice 25mm rim that also happens to be strong as hell. Granted I never tried WT tyres as they weren’t available but they’re a solution to a problem that needn’t exist. The correct way to address tyre stability is to run appropriate pressures and stiffer tyres.
A while ago RC said he knows of nobody who has tried wide rims and gone back and now the same sentiment from MW. Well RC don’t know me but I’ve done just that. I tried it, it sucked. Then I tried 25mm and a 2.5” DH casing and it didn’t suck.
  • + 10
 I’m the same, don’t like the way wider rims square off the tyre creating vague turn in, 25mm with 2.35 magic Mary i find is perfect...
  • + 1
 Perfect! I agree@jimoxbox:
  • + 8
 @MattWragg - Does this review not play a bit into confirmation bias though? I think it would be a worthwhile effort to have bland testing, as in, not knowing what rim width you're riding on a given run and then recording your data. That way it should help eliminate the factor of "well I know wider is better" against the clock.
Just a suggestion.
  • + 8
 @mountainbikerfisher: Ooh a critical thinking person! What woodwork did you come out from? LoL Big Grin
  • + 1
 I presume you mean blind testing? Wink

To follow that logic through, every test and review is fallible in that respect. "Am I right?" is maybe not the ideal starting point, but then conversely, if I had been running 25mm rims these past years, would that not also affect the outcome? To have someone test utterly without preconceptions, they would need to have never ridden a mountain bike before (or read Pinkbike), but then obviously they wouldn't understand enough to waffle on about it for 4,000 (hopefully meaningful) words.

There are also a number of practical problems with blind testing - first logistics. You need a support crew to do that, which I don't have normally, this test was me, a pump, a pressure gauge and a boot full of wheels and tyres. That is solvable, but it creates a lot more work and I am a freelancer who has to juggle a bunch of commitments to make my living. Second, how blind is blind? For instance, if we're being ultra-precise here, if I look down at my wheel before the run I should be able to see the profile and figure out the combination, would that invalidate the test? You cannot ride without seeing the overall profile of your front tyre. The only way you could do a truly blind test would be to ride blind(folded?).

That said, I do agree that a blind test would be better and it was something I was originally trying to do, but life, etc got in the way as I was originally hoping DT would come down to me for the test.
  • + 3
 @mattwragg: Sounds like excuses...
  • + 2
 @mattwragg: Thanks for replying Matt!
I like what you did to be honest, and I see where you are going with logistical aspects. To a certain extent I can see that a rider may be able to look down at their wheel and have an idea what size rim the tire was running, so how to pulling off a proper blind test may prove to be challenging.

Just wanted to put that as a suggestion if in the future you were able to get the resources (crew) and method I would be very interested in the results.

My own confirmation bias is that 25mm rims with 2.35" tires is pretty good (that's what I'm running and why I'm biased) but if someone offered me a free set of 30mm rims to run my tires on, I wouldn't say no Smile
  • + 8
 @mattwragg What about flats ? Some say wider rims expose the tyre flanks and make them more prone to flats.
Other interesting thing : Clementz, Vouilloz and Dailly often run narrower rims back to obtain a rounder profile and reduce rolling resistance.
  • + 2
 I personally don't buy into the flats theory, if anything I would say I have had fewer flats since going to wider rims, but that's anecdotal. Maybe for racers it's different, or with another tyre brand, I couldn't say, but with the Schwalbe tyres I usually run it hasn't been an issue.

There are a few things to pick apart there. Firstly, I haven't seen Nico or Adrien do it, but I might be wrong. Clementz pushed Mavic in that direction and a lot of the guys around him in Northern France/the Vosges do run that setup, I have seen it less here in the South. I know Barel doesn't go in for it out of choice. Rolling resistance is a non-argument, I know DT have done testing with the Swiss national team and claim to have proven that 30mm is preferable (I haven't seen the data to verify that, but I trust the people I know at DT when they tell me that) - Florian Vogel did much of the testing and now runs 30mm XMC1200s at WC XCO based on that data and I know Nino was part of that test too. As for weight, I personally don't see what 30g will gain you. Maybe some of those guys like the profile, I can't say, but I personally don't like having mismatched feel from front to rear, and I don't like the rounder profile of the 25mm rim.
  • + 2
 More flats was definitely my experience when I went from 22mm to 30mm. Suddenly I was getting tire casing pinch flats / snake bite (tubeless set up) a lot more than previously with the same air pressures. However, my 22 mm rims were aluminum and my 30mm were carbon so that may also be a factor. I'm a big guy though (100kgs+ riding weight) so there's that as well.

After that I went ProCore and never looked back. ProCore also provides so much support in a 25mm rim (which is what I run a lot of the time now) with a 2.35" tire that I think it completely negates the stability advantage of wider rims. At that point it just comes down to what tire profile works best for you with the tire you are using.
  • + 1
 @mattwragg: I did run smaller tire's ony rear for almost a year.

2,3" rear from MAXXIS or 2,25" from onza on 24mm rim. I switched to 30 mm and almost instantly hat flat's. Ripped the flanges open in no time. My home trails have no single flow trail. Only rock's and deep roots.

Switched to onza 2,4" with same thread and no flat's also instant. Conclusion is simple that there is a balance.

I will install a new minion semi slick today with 2,3" because there is no Enduro version of it with a wider thread. I don't think it will work for long time.
  • + 7
 Well, if you run the same pressure regardless of rim width, the larger rims will in fact be "harder" pumped and have lower rolling resistance. Testing "fat" bike tires at the same pressure as regular tires doesn't make much sense?
You should compensate in pressure due to the larger volume, as you explained here "Inflating the tires in ascending order with a regular pump, it was noticeable how much more air it took to inflate the tire on the wider rims".
  • - 2
 I don't get it... wider rims require more air to achieve same pressure because they create a bigger air chamber with the same tire.
But why would you say that tires mounted on wider rims would be "harder" at equal pressure?
  • + 3
 @t1000: For simplicity, if you pump up a 3" tire to 20 psi, it will be much harder to compress than a standard 2.4" tire at 20 psi. Using a wider rim with the same tire will have the same effect (to a certain degree), as the air chamber will be larger.
The outward "stress" on the casing is what supports the load, which means a larger air chamber (wide rim) at the same pressure as a smaller (narrow rim), will be harder, in fact stressing the rim harder as well. For equal load on rim and surface it has to be compensated by calculating the difference in volume. Basically, you equalize the hoop stress so it's the same for both rim widths, en.wikipedia.org/wiki/Cylinder_stress
  • + 1
 I see your point now and that's interesting. It's probably not that easy though to calculate the volume difference as you change rim width, as the sectional shape of the air chamber isn't so simple.
  • + 2
 Agreed, no sense in running same tyre pressures at all...massive difference in air volume between 22.5mm and 35mm rims
  • + 1
 @t1000: Assuming a similar circular shape that scales with rim width, I get 10% lower pressure for 40 mm internal width than 25 mm, which is significant in terms of rolling as well as bump absorption. Simply 60.4/65.5 and you get the pressure ratio. Or, calculating the new circumference based on the wider rim width, I get a casing width of 65.2 mm for 40 mm rim.
  • + 1
 @konken: I'm not convinced that's accurate. You are talking hoop stresses created by a pressure differential, but a "harder" tire seems like it has more to do with radial forces (perpendicular to the hoop stress). If we ignore any differences in support provided by the tire casing, then wouldn't the perception of "hardness" or "compliance", if you will, be simply due to a change in internal pressure pushing against the ground?

Take a tire with, say, 10L of volume at 20psi, and press it against the ground with a force of 100lbs. If you trace the contact patch, it will be 5 square inches (assuming a very soft casing).

Now take a tire with 100L of volume at 20psi, and press it against the ground with a force of 100lbs. You will have the same 5 square inches of contact, even though the volume is ten times as large.

To me, that means they are exactly the same "hardness" -- they compress exactly the same amount.
  • + 1
 @marky-d: I think your example is physically impossible, the force is distributed per unit area across the whole "hull". If the outer hull is identical, higher pressure will result in a smaller contact patch. Keeping the pressure the same, and increasing the diameter will have the same effect, as the force exerted by the tire scale by both variables. You cannot have the same contact patch without lowering the pressure with the larger rim.
  • + 1
 The key term here is "casing tension". It is directly proportional to width and pressure. The 40mm rear should have been around 25psi to get the same tension as the 22mm if my math is correct. This is a significant oversight, sorry man.
  • + 1
 @konken: sorry, but the diameter at widest point ones not give you the basis for comparing the air volume. The cross section shows you just how different it is between rim widths.
  • + 1
 @JohanG: Thanks for this, I've been able to understand more with your comment and a search, would you please elaborate on your calculation? for a simpleton to comprehend?

I don't think anyone can deny that a lower volume tyre feels softer than a higher volume tyre at the same pressure. I've never understood the comments that a higher volume tyre 'allows' you to run lower pressure, as some sort of advantage, I HAVE to run lower pressure to get a higher volume tyre to perform and therefore the advantage of a higher volume tyre has little to do with a lower pressure, n'est-ce pas?
  • + 1
 @Travel66: Using the casing width as diameter is only an approximation, but it scales pretty well in terms of "correct" pressures. Measuring/modeling the shape of the casing would give a more exact result.

@JohanG: Exactly, this "nullifies" the test pretty much, at least a dummy with different pressure should be used. As mountainbikers, we all SHOULD know that tire pressure is far more important than rim width...
  • + 1
 @Braindrain: I'm not sure I understand your reasoning in the second paragraph. This page has the math, but it simplifies to a simple equation. flocycling.blogspot.com/2014/11/flo-cycling-why-do-you-use-less-tire.html
  • + 1
 @konken: Impossible? It's basic physics: the force exerted by the ground must be equal to the force generated by the pressure inside the tire. By definition, if the internal pressure is 20psi, it will exert 20psi*5 square inches = 100lbs against a 100lb force.

One could argue that the formation of the contact patch actually decreases the internal volume (I'm not sure if or how much that's the case, but it's reasonable), and thereby increases the internal pressure. In that case, it would be safe to assume the lower-volume tire pressure would actually increase MORE for a given load, resulting in a HARDER feel than the large-volume tire at the same initial pressure!

It still seems like you are interested in looking at the hoop stresses, or the "casing tension", as @JohanG notes -- but I maintain that that does not translate into tire "hardness", as hardness is going to a perception of force perpendicular to the hoop stress.

I could see your interpretation if you picture the tire as a sheet of rubber held between two rigid grips: with a low tension, it will feel 'softer' than if it is under high tension. However, in the case of a real tire, the rigid grips aren't there; the casing is able to deform and adjust it's shape in order to minimize the internal pressure of the tire.
  • + 1
 What I mean with impossible is, having a volume of 10L and 20L with equal pressure having the same contact patch. If so, a fat bike tire would be as soft as a standard tire at 20 psi, but that's not the case. The force to the ground is of course the same, but not the contact patch. You compensate to a lower pressure for the high volume casing to get the contact patch/footprint you want.
  • + 2
 @JohanG: thank you for the link. It's ok, I was just having a moan that wasn't well constructed! I know what I mean and I am glad I have a greater understanding. Essentially a larger tyre diameter needs less pressure to achieve the same contact patch area, all else being equal, in this instance the increase in rim width is increasing diameter. This reflects my real world observations, I've never understood why.
  • + 1
 @marky-d: I understand your reasoning, there is another factor. Consider a skinny road tyre, 25mm diameter at 20psi- that's much too soft to ride. Now consider a fat tyre 4.8 inches 120mm diameter at 20psi-this is far too hard to ride. Given a load of 100lbs, the 25mm diameter tyre will be flat on the floor and the 120mm fat tyre will hardly be compressed, so they may both approach a contact patch of 5 inches square, but it is clear this is not ideal. So for real world riding considering the hoop stress/ casing tension and accounting for diameter with pressure choices makes sense even if it isn't a perfect system.
  • + 5
 It’s just about tyre profile,anyone who has ridden motorbikes will show you that narrow rims give a rounded profile for ease of leaning over and traction when cornering.wider rims give a squarer profile for digging in flat corners and getting power down.
  • + 4
 You have the best username I’ve ever seen here.
  • + 5
 "If the carcass and overall volume feel good, would it not be possible to re-work a 2.35 tyre's tread to suit?"

Exactly. I'm interested to know what would happen if a 2.8" or 3" tire's tread was put on a 2.5" casing, then mounted on a 40 mm or 50 mm rim. Might be a disaster or it might be the only way to get a wide footprint with a light casing that doesn't suffer lateral collapse.
  • + 2
 Lower the profile of the tyre and increase sidewall stiffness and you'd get negligible collapse and reduce or remove side wall pinching even a lower psi, though running high psi remove the risk of flats and let the flat wide rubber with decent knobs to do the work. (Lol "decent knobs to the work"
Giggles) like a moto tyre.
  • + 2
 That is actually what happened with 29+, if you read the reviews (I am pestering Trek to try one at the moment), I have seen a few people praising them for sidewall support precisely because they reduced the height.
  • + 6
 Will become pretty academic when we all start using tyre inserts in the next couple of years. This will make wide tyres redundant and the 25mm rim will start looking good again.
  • + 2
 Speak for yourself. I'm still using tubes..
  • + 6
 Wants to not talk about 'feelings', and proceeds to write an article based on his feelings. Too funny. LoL

DT Swiss ex 471 is THE best rim for your $€£¥.
  • + 5
 Very well written, cheers.
However Inconclusive.
Moral of the story:
Run what your bike came with OE.
When buying aftermarket,
buy what suits your Budget,
(ie: what's on sale @ CRC)
Unless you're a Dentist.
  • + 1
 @XCSUR4: You forgot the bacon!
  • + 1
 @m1dg3t:

How did U guess that?
My favourite 3 items on pizza
Bacon Bacon & Bacon
  • + 4
 2.35 tires -> 30mm rims
2.6 tires -> 35mm rims
Industry trend for 2019: 2.6 tires on 30mm rims

However, since most riders suffer dents on their rear wheel prioritising increased stability over rim width here seems reasonable especially since gains in sidewall stiffness are better felt on the front wheel when cornering hard and most riders run the rear tire at a higher air pressure anyway, further marginalising any theoretical advantages of a wider rim.

Width vs. Stability

A 30mm wide DT EX511 enduro/DH rim has the same weight as a 35mm wide DT XM521 allmountain rim but is far more robust. A narrower rim also makes the tire rounder, reducing rolling resistance and sidewall exposure.
  • + 3
 You measured a 0.1mm difference in tread width between the 25mm rim and the 30mm rim. That's a negligible difference in tire shape and you won't notice it on the trail.

This is why enduro/DH pros run rims in the 26-27mm range, even with Maxxis WT tires. They are lighter and also less likely to cut a tire/get damaged than rims in the 30-35mm range, yet they ride the same.
  • + 3
 Shame you used a bike that equates to the average riders do it all bike, but the just ran lift assisted tame DH. That setup for average Joe would be expected to ride on the flat and up hills as well yet tested it just down hill. How did the 25mm compare to the 35mm on the flat or up hill? 35mm Kill the pace make it harder work at all? I suspect it did.
  • + 3
 Went with LB38s years ago drinking the koolaid, and after switching back to 23mm inner 30mm outer if you lean the bike way over the front tire drifts and hooks up way more predictably, and washes out less having cornering knobs on the side. That's with a DHF 2.5WT. My experience is wide rims feel awesome in straight line technical downhills but give up a lot in the cornering department.
  • + 3
 Thank you, this is something I was wondering about recently and I wanted to pay attention to the bike checks of the EWS Racers to see what they are actually running.

POLE and Mavic seem to prefer not so wide rims (see polebicycles.com/the-tipping-point). On the other hand, the IBIS rims with 36mm inner width get praise and Santa Cruz just brought out a 37mm.
  • + 3
 I'm downsizing to 30mm ID, from my 36mm ID rims at the moment on my 2.35 Schwalbes,
The sidewall is just too far out, and taking too much abuse when under hard cornering.
I'm starting to see the sealant weeping through the fabric around the base of the edge knobs, and around the flat of the sidewall after only 6months use.
(and thats on the Heavy duty "Ebike" Nobby Nic)
  • + 2
 Just to clarify, the question is not if wider rims are better but rather at which width (for a given tire size) further gains are neglectable and a more robust but slightly narrower rim may be the better choice. (concept of marginal utility)

In order to truly leverage a wide rim you need a tire that was designed for it. The author decided to use 2.35 tires which are not optimized for rim widths over 30mm. A 2.6 tires has roughly the same width but a much better shape on a wider rim since it was designed for it.
  • + 2
 28 psi in a rock razor? Im 100kg running a super gravity casing rr on mk2 stans flow which run at 25 internal width. I run 25 psi set with a topeak digital guage and it feels planted. Could even go to 24 maybe. 28 seems very hard.
That set up sees me through bike park days and big days in the hills.
Equally I run a hans dampf on the front at 26 psi.
Would you get more grip from lower presures?
  • + 2
 He is not running super gravity casings..
  • + 2
 I would like to have seen the comparison with a loop, up & down rather than just lift assisted.
A friend tried the wide rims and noticed a big change to the rolling resistance, not for the better!
Went back to the medium wide rims. Your narrow.
  • + 2
 Interesting test, and I understand the idea of keeping everything constant apart from the rim width. But wouldn't it be more realistic to adjust air pressures according to the rim widths? Since the total air volume increases considerably from say 25 mm to 35 mm, you should be able to get away with slightly lower pressures. @mattwragg
  • + 2
 Perhaps another thing to consider is flat protection? Maybe a narrow rim with its bulging carcass protects the rim more than a carcass than is more vertical?
I tend to float between 2.35 when I have to pedal, and 2.5 if I'm shuttling, with stickier rubber. Going faster usually has more to do with me staying off the brakes than anything on my bike!
  • + 2
 Playing with the tire pressure interests me, but adds a huge variable to something like this. I wonder if you took 30/35mm rims and then did incremental tire pressures if you would change your mind?

I also want to know opinions of WC DH folks. I see a whole lot of DT EX471 wheels being run, which have a 25mm internal width, on WC DH tracks. What is drawing those insanely fast riders to the opposite side of the width spectrum? Is it that they run big DH casings and can rely more on that for support in corners?

Great article and experiment, though, I love this kind of content.
  • + 2
 The clock doesn’t lie Matt, really? Well that’s more or less how the graph of subsequent laps on gokart track looks like everytime I go there and I don’t change anything between laps. And variables are way fewer.

I love the article but having been trying all these widths and also these tyres I can see clearly how it comes down to feel, not the clocl. I can easily settle for 30mm it does offer better support in smooth corners, but it is sounter productive in bumpy turns since there is less tyre displacement thus less “sideways suspension”. I talked to two World Cup riders about it, they did prefer 25-30mm range. Feel, let’s leave the clock out of this
  • + 2
 Going from Stans flow mk2 (25.5 internal width I think) to Stans flow MK3 (29 iw) hasn't allowed me to drop rear tire pressure at all without getting tire roll in corners or rim contact on rocks. It has allowed me to drop 2-3 psi in the front tire. Makes me think Mavic is on to something with those staggard rim widths.
  • + 2
 Interesting test. I assuming you were just checking on something you wondered about that you thought might be an interesting basis for a pinkbike article, rather than running your research by us to ensure your everything was in order before you allowed a physics or engineering journal to publish it. Obviously different tire widths and pressures would change it, and of course if a person really wanted to test this stuff objectively an actual human riding a bike on a variable course isn't going to give easily repeatable results. If we wanted objectivity it would have to be some sort of equipment set up to do exactly the same thing on the same type of terrain each time and I suspect there is really not all that much of that sort of testing of tires and wheels in the bicycle industry. It would be too expensive, especially compared to paying somebody who is going to ride very fast on almost anything to use it to win races and say its a great set up. Most people buying bikes are going to be more influenced by that type of marketing anyway. I thought it was a fun article and enjoyed reading it
  • + 3
 It would be really interesting to know about rim strength in relation to rim width. Are wider rims more likely to suffer from dents and dings, with the rim closer to danger while cornering?
  • + 1
 This, this, this...
  • + 1
 It depends on the rim, not the width. It certainly is harder to resist dents with a wider profile, but you cannot generalise between brands.
  • + 2
 I'm running the Maxxis 2.4 DHRII WT tires on all my bikes. On 30mm internal width rims, I can feel squirming and burps on aggressive corners. On the 35mm internal rims, I have experienced no squirming and burping. I run 20f/25r psi. I never did any scientific comparisons, but my general impression is that the 35mm internal width rims provide more tire support. Plus, they look bad ass.

I plan on trying out a set of 2.6 Forekasters as my next tire. I think a 35mm internal width rim would be ideal for a 2.6 tire.

Seems like tire size preference is related to the trails we frequently ride. My friends in Minnesota don't run anything larger than 2.3 tires while my friends in Boulder City don't run anything smaller than a 2.5 tire. Most people at Bootleg are running 2.6 and larger.
  • + 2
 I meant to add, rim width is therefore related to desired tire size.

i25mm rim for 2.3" tire or less.
i30mm rim for 2.3"-2.5" tires.
i35mm rim for 2.5" - 2.8" tires.
Maxxis WT 2.4/2.5" tires are designed for i30-i35mm rims.

Their older tires always measured narrower, but the new Maxxis tire sizes are true to size.
  • + 1
 @sriracha: Spot on dude... you articulated the point i tried to make much better.
  • + 2
 I honestly didn't even know what my rim width was. Had to look it up on the YT site. It says 30mm, but I'm not clear as to whether that's internal or external width. I always thought the wider rims were better for wider tires, and vice versa, so if you planned to run a wider tire, you should have a wider rim. But that was just an assumption.
  • + 2
 Really interesting article, and yes, there are so many other factors that can cloud or compensate effectiveness. Tyre wall stiffness and profile are one area that can also change how the bike grips and feels. It's a can of worms for sure.
  • + 2
 Perfect timing: I went from an old ZTR Flow 26" to Race Face AR30 29".

Faster, more grip ..... More positive aspects than imagined.

But: I rode the same track for years and never managed to dent the rim. I am putting a new dent in the AR30 on nearly every second run.

They have to make those rims more durable. I think I will need new rims this summer and going to try the Newmen Rims. They do offer a different geometry and are said to be tougher.
  • + 5
 That might be less to do with the AR30s being wider and more to do with them being made of cheese..
  • + 1
 I had Arc 25s and I put a dent in it that stopped it from running tubeless while I had 24PSI in it. After pumping it up to 28PSI and putting a tube in it I still had two more, even larger, dents in it by the time I replaced it. I don't think I'll ever buy Arc rims again, though their new Arc "heavy duty" rim seems interesting. I replaced mine with Stans Flow rims but I've since been told that these are also pretty soft. I've just stuck a Cushcore in the back to protect the wheel now.
  • + 1
 May all our wives protect us from knowledge of Derby Ray and Keith Bontrager. This is a nondefinitive test which results in a Verdict that goes both ways and which could have been conducted for half price on Sun product. I liked WTs on 30ish.
  • + 1
 Cant use the same tire width on all the rims, not using the rims as intended... a 40mm rim with a tire designed for a 30 - 35mm rim is of course going to under-perform in comparison. Take a 3" tire and mount it to the 30mm rim and see what you think.... it'd be the same disadvantage you are giving the 40mm rim. With that said, for the riding I do and most do i think 40mm is too wide... but to be fair in your comparison.
  • + 1
 Put it in writing, and it must be true.

The Syntace graphic gives a distorted view. If you have a longer sidewall, you will have to increase internal pressure to prevent side-roll with the wider rim. A fatter tire on a narrower rim at the same pressure wouldn't roll as much, until you reach the bead's breaking-point. You can be too wide of tire for a rim. For a standard 25mm rim, that limit is about 2.4 inches. In halcyon days of 17mm rims, the 2.2 inch tire was pretty much the limit, with 1.95 to 2.1 being the sweet spot.

Wider doesn't make you faster - it just creates "new" standards for the marketing guys.
  • + 1
 Thanks for the work on this article. Well written and well executed. You're honest about personal bias and that this isn't a scientific article, not sure why all the bitching and moaning.
Personally, I've settled on 35mm carbon NOX Farlows. Night and day compared to 25mm AL wheels. Apples to oranges, perhaps, but a huge difference in grip and precision. It also allowed me to run 2.5 WT DHR/Agressor combo that is rock solid on 95% of terrain.
  • + 1
 I switched from a narrow OEM Giant rim to a WTB rim in 30mm width. I also changed from Schwalbe Nobby Nic's to Conti Trail Kings. The difference was apparent as soon as I started riding and I actually had to get used to the new set up.

I agree that upgrading to wider rims just to do so is not necessary but if you find yourself in a position that you need to, you should. And I also agree all my future bikes will have wider stock rims on them. For what it's worth I'm 5' 10" 210 pounds.
  • + 1
 Optimal rim width varies depending on almost too many factors. Tire volume and tread width on the casing when flat is a way of comparing tires. If you're going with a 2.6 tire that has more volume because of a bit wider casing and pares that with a wider tread you can use those characteristics on a wider rim at lower pressure to get a bigger footprint. Then you have to match that with the terrain and speed. That combo, for me, works better at medium speeds You pick the knob size and height depending on hardpack vs loamy trail surface.
  • + 1
 Smug no it all face for me. Was riding wide mavic ex729s on my trial bike back in 2010 cuz skinny rims sucked at everything bar weight. Made the bike abit of a tank but it was better than the alternative. Was coming of mx at the time so was trying to replicate the same feeling and durability which couldn't get with skinnys. Now I'm on light wide carbon rims I couldn't be happier. All the zip and all the grip I could need Another 30-35 mm for life person.
  • + 1
 A thought: Personally i always get faster in the morning and then i get tired and i get slower again. My times throughout the day with same bike/rim/tire usually look kind of what your times show.
How about a control day in your experiment repeating the test in reversed rim order or with one rim next day with hopefully same weather conditions?
You always have to have a control group in an experiment!

Oh yes, i had some fun with the SYNTACE graphic too...
Isn't That Green tire is way bigger than the red one?
What if i put the red tire on the wider rim?

www.pinkbike.com/photo/16105672

oha, doesn't fit? makes things even worth? or is it all just artistic freedom?

I guess what i want to say anyway graphics like that are fun... anyone can draw up whatever story they want to tell/sell... you did a really great test, argued very reasonable and logic.... but that marketing graphic to start out with really set the wrong tone and doesn't do the article justice at all...
  • + 1
 I run two wheelsets in my bike and regularly change between them on the same day. 25mm rims run 2.3DHF/2.25 Ardent combo and the 30mm rims run 2.5wt DHF/ 2.3 DHF combo. I agree that a 2.35 rock razor isn't the best on a 25mm internal I found it to sqirm a bit too much in hard corners. I had no problems with 2.35 Magic Mary on the front of either rim size.
  • + 5
 Maybe Loic will switch to wider after washing out at the last race.
  • + 1
 I'm obsessed with this subject. For me a 35 carbon with those 2.4 or 2.5 Wide tires rule. Sun Ringle has Duroc 35 with a nice hub, 32 id and both drivers included for a decent price. My road bike is a steel monster cross with a 25id and 2.1 Thunder Burts. 157 trail seems to be next. All that space and stiffness begs for more rim and meaty tires.
  • + 1
 sorry but are you referring to internal or external width?

schwalbe make the widest tyres on the market. to give you an idea.... a 2.35 magic mary is slightly wider profile than a wt 2.5 maxxis minion! i would never try a 2.35 maxxis on a rim that wide but the schwalbe is fine.

i went from 29mm internal to 35mm internal using the same 2.35 magic mary and feel the cornering is just as good but you notice the more volume with the bigger rim. the extra width also helps keep the sidewall in place at hard cornering. my 29mm i could not run any lower than 23psi otherwise the tyres would deform. not so with the 35mm internals.
  • + 1
 Now just ask tire manufacturers to make tyres that fit the available rims on the market, putting a 2.35 mm on a 40mm rim it's obvious that's not gonna work, just by the look of it, but a 2.5WT shorty will do the job, although a bit vague on feeling as the casing of exo is a bit weak. A dh casing WT shorty in 29 is all I need.Don't care about weight
  • + 1
 Great to see some analysis like this Matt- obviously only so scientific you can go but I have to say your empirical findings do line up with my "feelings" of riding different rim widths over the years.

The caveat of different tires creating different results is in part true but if we take the average tyre as being a Schwalbe 2.35 or Maxis 2.4/2.5 wt which are about the same caracas width, then I think the analysis holds true. Run narrow tyres then they will square off on narrower rims obviously.
  • + 1
 Until recently I ran Schwalbe 26x2.4" tires front and rear on quite narrow rims with latex tubes. Not sure what type exactly (I always peel of the stickers before I lace them). I'm not one to tell you what exactly happens to the tires when I'm riding, but when I suddenly lose grip, hear a loud bang and find grass between the rim and tire bead I guess I experienced some tire roll. But that is all I can tell. How the tire conforms to the ground, which knobs are gripping etc, sorry I've got no eyes down there. For my latest build I went with 29mm (internal) wide rims, 26x2.4" front (Continental) and 26x2.35" rear (Schwalbe). Schwalbe doesn't seem to do 26x2.4" anymore. I don't use regular latex tubes anymore, but Schwalbe Procore. To get an idea of which knobs I'm using, I thought it might be good to keep an eye on how the hairs on the tires wear. It seems I lose them from the side knobs just as quick as from the middle, except for those on the outside of the outer knobs. Which makes sense. It is hard to get grip from the outer edge of the outer knobs. It is the inner edge that helps, not the outer edge. If I go that far, it may be when I'm already sliding. So we may simply not go handlebar-to-the-ground low on level turns. Even if you drop the outside foot and tilt the bike as far as you can (I purposely had my frame built low to give me all the room I could ever want) there simply is no more useful tire contact patch to rely on. Those really low corners can probably only be done when you have a berm for support. And in that Matt Hunter add where his bars are scraping the dirt the apex was actually the highest point so he even had gravity helping him.

tl;dr: I'm impressed if people can objectively assess how far they're tilting their bikes in corners and what their tires are doing exactly. Unless you're already sliding, you probably can't consistently tilt them much further than as shown in the second picture from the top.
  • + 1
 I like wide rims...and I can not lie! 30 mm i.w rims, with Super gravity casing for trail/ enduro racing has been wicked so far: lower pressure for better grip and comfort, added corner stability and No flats so far ( tube less, 29", 22 psi up front, 24 psi rear, ca 85 kg geared up)
  • + 0
 Thank you for the test, great work! The results seem reasonable and likely fairly accurate. The conclusions reached also seem reasonable.
* Two points of observation:
1.) A more scientific approach using a time record GPS based device that allows you to do a track overlay or a at least a recorded time vs. top speed, max/min g-forces, acceleration, etc. I am sure the manufactures would likewise loan a unit out for testing in exchange for advertising mention.

2.) The 40mm should be equal in testing iterations, as removing it (regardless of reason) yields a skewed test.

Again, thank you for the time and energy to setup this test. Looking forward to future articles from you.
  • + 0
 Well written article showing insight to riders on a fairly difficult to test subject on rim widths. We agree with Matts’ finding, and based on the spectrum of tire preference and available tire selection in the market, we opted not to make 40mm rims at Tairin, getting the range down to 25mm - 30mm - and 35mm for MTB. Weight gain with only a subtle performance gain, plus a decrease in side thread protrusion, are the main properties we concluded when going too wide (ie 35mm on 2.35" and 40mm on 2.5~2.8") We've been recommending 30mm for general riding at 2.1~2.5" tires on fairly low psi (anything bellow 35psi) and 25mm at 1.8~2.4" for anything above 35psi. And 35mm for 2.5+ plus tires up to 3.0" at pressures bellow 23psi.
  • + 3
 So what I got from this is 2.35 is good for 30mm Id rim. So what is Tyre is good for 2.5? 35mm-40mm?
  • + 1
 Would make a good follow up. Does a 2.6" Magic Mary tyre on 35 / 40mm rim make for a faster / better combo again, or does the weight offset the benefits? Other than weight, does going that wide have any other drawbacks?
  • + 1
 You made a mistake with the pressures. You should have inflated to a consistent casing tension. Starting at 28psi for the rear on the i22 would have gone down to around 25lbs on the i40mm.
  • + 3
 interesting but yeah 2.5 tyres on 25mm 30mm 35mm is the test i want to see. Let me know if you need help!
  • + 1
 I run a 35mm front rim and a 29mm rear rim this gives me a really great tire profile for the tires I knew I was gonna be using when I built my last bike
  • + 1
 Maxxis recommends sizing be 1.5-2.0 of rim so a ideal tire on a i30 rim would be 45mm-60mm wide this was stated by a Maxxis engineer in a interview I read while ago
  • + 1
 Everything is proportional to body size. Too bad more people don't understand that rather than going by what their favorite rider, buddy or marketing says.
  • + 0
 Interesting! But I have a XC bike, an endure bike, 2 free ride bikes an a DH bike. All with different size wheels and rims, I just ride the shit out of all of them.. Yours truly, Nuff Sed
  • + 1
 There are standards for reccomened rim width/tire size. As long as those are respected, tires and rim will work as intended. It used to be listed online.
  • + 3
 Dude, where are your gloves?
  • + 2
 @mattwragg
Awesome! More please. This and your frame geo musings are currently the most interesting reads on PB
  • + 2
 So at what width is a WT Minion/HR2 tyre needed instead of a standard one ? 30 or 35mm ?
  • + 1
 There were designed around a rim profile between 30-35mm internal. According to the interviews when maxxis launched the WT tyres.
  • + 1
 Anyone have suggestions for a wider rim in 26"? I'm not ready yet to ditch my Yeti SB66, but I think it would be fun to freshen it up if there really is a difference...
  • + 1
 WTB has 35 inner width 26” rims
  • + 1
 I've got a new pair of addix Magic Mary 26x2.35 super gravity and the casing is only like 55mm on a 28mm internal width rim, at like 50 psi. What gives?
  • + 3
 well written.
  • + 1
 nice article. Always been curious on this as a 54kg rider on 30mm rims running low 20s psi on 2.5'' tires.
  • + 2
 Very thorough test, well done and thanks!
  • + 1
 Just the fact of thinking you should go slower on "narrow rims" could cont for 7 seconds.
  • + 1
 nice article, still pondering whether to get some flows or stick with my tech enduro's hmmmmm
  • + 1
 Can you do a semi-scientific test like this to prove that 26" is the superior wheel size?
  • + 1
 I did, although I have since sold my 26 and 27.5 bikes for 29ers as my opinions have changed in the 6 years since I wrote this.

www.pinkbike.com/news/26-vs-275-vs-29-Wheels.html
  • + 2
 You win. You are the king of bike nerds.
  • + 0
 People just need to learn how to ride! I just look at the biking pictures on this article and see the rider with a bad technique!
  • + 0
 People buy into this marketing BS? You can have the widest or skinniest rims, but what matters most are tire size, tire sidewalls, and most importantly the tire air pressure!
  • + 2
 Missed the blind test. Most important thing in any controlled study.
  • + 1
 I remember bruni saying that he don't care and prefer ride a smaller rim. Wider is not better.
  • + 1
 Wider is better no matter what. I will always choose a wider rim for all of my bikes
  • + 2
 Should have been on supergravity casing. No wonder 25mm felt vague
  • + 1
 @mattwragg Thank you for doing this test for us! Love it.
  • + 1
 And that sizing/reach article from while back is great
  • + 1
 so you're saying my 19mm ID rims are outdated....
  • + 4
 No, not if you're having fun riding on them.
  • + 1
 Yes, sell sell sell..whoops, no buyers just recycle em
  • + 1
 @mattwragg What about a 25mm rear, 30mm front combo?
  • + 1
 I'm not a fan, I guess I should have tested it here, but I don't like having a different feeling front to rear. It was on the rear I was struggling most with the 25mm rim. That said, that was also partly down to how short the chainstays are on this bike, which I really didn't get on with, but from my runs on the 25mm I didn't feel there was anything there I wanted to explore further - but maybe 35/30 is worth a go...
  • + 2
 @mattwragg: I intend to build my next bike around 29" EX511 front and EX471 rear rims in a frame with 445±5mm chainstays.
  • + 1
 @mattwragg: The staggered tire and rim widths are to give good front grip while having a light rear for pedaling so the downhill test wouldn't show the benefits.
  • + 1
 @casman86: I know what they are for and I have used them in the past, I do not, however, like them or think they offer any advantage.
  • + 4
 @mattwragg: " I don't like having a different feeling front to rear" and used different tires, hmm, interesting...
  • + 0
 Cool test bro.
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