Behind the Numbers: Specialized Stumpjumper EVO 29 Suspension Analysis

Jun 13, 2019
by Dan Roberts  



If you'd like to know more about the Behind the Numbers series, aren't familiar with the terms being used or want to know why we're doing it then check out our Introduction article for all the information.

First up in our Behind the Numbers series is the Specialized Stumpjumper EVO 29.

The Stumpjumper EVO uses a familiar suspension layout from Specialized, but with quite an unfamiliar geometry. The bike is a big departure from their usual conservative angles and lengths.

Stumpjumper EVO Analysis Details
Travel Rear: 138mm
Travel Front: 150mm
Wheel Size: 29
Frame Size: S3
COM Height: 1150mm
Chainring Size: 30T
Cassette Cog Sizes: 50T, 24T and 10T


Despite its short travel, when compared to the other bikes in the enduro category, it should gain buckets of stability and inspire confidence from its truly low, long and slack geometry.

The Stumpjumper bikes use shock extenders, which are a way of actuating the shock from a linkage system further away. They also enabled Specialized to maintain an uninterrupted seat tube, as the shock extender straddles the tube. However, these things seem to be growing in size across lots of brands, and while Specialized doesn’t win the award for longest extender, it’s still 69% the length of the shock.

While they have ditched their proprietary mount between the shock and extender, the shock extender is still going to increase the leverage on the shock shaft and internals. A bigger shafted air shock is going to help durability issues here, while adding vital adjustment options to the bottom out resistance. Sadly, shock manufacturers are now having to design for these increased side loads of MTBs, and hardly anyone seems keen to use spherical bearings.

Does the departure from the norm continue in the suspension? Have they added features to match the upped aggression of the geometry? Let's start to look closer at the characteristics of the suspension, beginning with the leverage ratio.






Leverage Ratio

The Stumpjumper EVO has 9.5% progression in the high position and 9.7% in the low position, with an average ratio of 2.76 in both settings. It has a linear to progressive to linear curve.

Having the progression percentage under 10% is going to push the rider into the predicament of which to prioritize – small bump sensitivity or bottom out resistance.

Setting the bike up with a normal amount of sag will result in good traction, as the suspension is not compressing a massive spring. But the linearity of the leverage ratio means that the bike will use excessive amounts of travel on features of the trail that don’t require that much travel, including inputs from the rider. Pumping the bike will result in more energy going into compressing the shock rather than maintaining forwards momentum.

Getting to the end of travel with this shock setup is going to be possible without too much hassle, especially with the final portion of travel becoming very linear indeed. And given that the carbon models come equipped with a coil shock, this also won’t help out here. The coil shock leaves no adjustment options for the end of travel like on an air unit.

This low progression coupled with an already low BB will probably bring some pedal clipping problems in chunky terrain and miss-timed pedalling scenarios.

Alternatively, the rider could prioritize not bottoming out all day long and over-spring the bike to save their ankles. This will, however, result in less small bump sensitivity and will make the bike ride dynamically higher. Given the really low BB, this might not be too bad. There’s definitely room to move in this direction without adversely affecting the geometry. How much over springing is required will depend on the aggressiveness of the rider.

Despite the long links of the Specialized layout, which give smooth curves for the acceleration responses, the shock is driven off quite a small link, and so this creates some subtle bumps in leverage ratio curve. Smoother curves generally translate to more predictable bikes, so there could be some room for improvement here. The overall size of the bike and the smaller amount of travel could go some way to masking these shapes in the leverage ratio curve.

Moving the chip to the high setting gets rid of a touch of that end stroke linearity, but now introduces a bit of regression at the beginning of travel. While it’s not at all a big amount of regression, 0.7%, it is taking a step down the road of potentially creating a problem for the damping continuously going back and forth over this hump and the changes in shaft speed that it brings.







Anti-Squat

All gears in both chip settings are under 100% anti-squat, and around sag it’s hovering around 80% and then drops off quickly.

Coming back to over springing, if this is the case, the bike would be running less sag and so have a touch more anti-squat as you'd sit higher in the curve.

The linearity of the leverage rate, the high overall ratios, and now the always below 100% anti-squat are going to result in a very active package.

Pedal kickback should never be a complaint on this bike, but it's a belief that good anti-squat numbers are more important. This is a common trend among many of the longer established companies. Pedal kickback probably got prioritized at some point in the past, and the anti-squat suffered as a result. It’s a shame that this got carried through for so many generations of Specialized bikes, but perhaps things will change for future generations of Specialized bikes after seeing the layout of the prototype Demo that's being raced at the DH World Cups.

In any case, it's likely that the Stumpjumper's climb switch will come in handy, as the weight transfer from accelerating and the cyclical mass of your legs spinning are going to use some of the suspension travel while climbing. Further into the cassette, and more in situations that might entail sprinting, the anti-squat really drops off. When that number drops under 0% the bike will further help compress the suspension, rather than counteract the weight transfer. But it’s good that most people won’t be sprinting at almost full travel, and the mass transfer effect will be less at these higher bike speeds.

The curves are nice and smooth however, unlike, for example, the short link bikes in this category. This is due to the long distances between the pivots, meaning that each frame member that defines the instant centre is rotating through less of an angle, and doing the rotation less violently. The high chip position gives a small boost of anti-squat in all gears, and this, along with the steepened seat tube angle, should help a tiny bit with the pedalling performance.







Anti-Rise

The Stumpjumper EVO maintains low levels of anti-rise throughout its travel, which might go towards creating some vagueness at the rear contact patch when on the brakes. The mass transfer forwards under braking will shift the riders weight forwards and lessen the force at the rear contact patch, reducing the ability to feel what's going on down there and allowing the wheel to break traction more easily.

The increasing anti-rise throughout the travel, however, is good for giving more support to the rider in high energy braking situations that will push the bike to the end of its travel.

As is the case with the anti-squat numbers, combining the anti-rise and leverage rate is going to result in a very active overall package. I’m sure lots of riders would appreciate this active, soft, and travel-using ride. But, given the bike's intent, which is clear from its geometry, I’m not sure the bikes kinematic is as up to the job of charging as the geometry is.







Axle Path

Given the low and far forward instant centre that is generating the low levels of acceleration response, the axle path is almost entirely a forward one.

For any bikes without a fixed main pivot, the instant centre will be a point in space that can move around as the bike compresses through its suspension. You can find the instant centre by seeing where the lines of the chain stay and link cross. In the case of the Stumpjumper EVO at zero travel, it's a point out in front of the front wheel, just slightly higher than the line of the axles. As the bike compresses, the instant centre quickly dips below the line of the rear axle and so the rear wheel follows a forward's trajectory.

But in the grand scheme of things this shouldn’t provide too much of a perceivable disadvantage to the rider as, depending on their riding aggression level, they would encounter more perceivable factors to deal with elsewhere with the design.






Final Thoughts

bigquotesOverall, the Stumpjumper EVO looks mean, and the geometry is an exciting jump forwards for Specialized. But after delving into the suspension it seems that there's still some of that conservatism there. The gross result of the suspension characteristics will be an generally active ride that will need some tuning to handle the aggressive riding that the geometry will enable. In my opinion the bite of this EVO bike doesn’t quite appear match its bark—on paper anyway.  Dan Roberts




Want to read about how the Stumpjumper EVO works out in the real world? Check out the review here.


Previous Behind the Numbers Articles:
Introducing Behind the Numbers - A New Suspension Analysis Series


251 Comments

  • + 56
 Excellent.
How rad would it be to set up a database with all current bikes..? Or at least an analysis of the Orbea Rallon. Wink
  • + 25
 Super linear (goes from like 2.6 to 2.4), the rest I can't remember.

I'm still not a fan of coil shocks on linear suspension designs, and I don't understand how people get to like the feeling, but heck, if you like the bike how it is, that's what counts the most!
  • + 1
 rallon has pretty similar leverage ratio. Some say it is too linear, but I as an owner don't think so. Smaller leverage ratio progressivity is damped more optimaly (think new cannondale dh project) and you can always add suspension progressivity by installing more volume reducers. I for example added one token (3 tokens in total) in X2 float on rallon and find it slightly over progressive for most of the stuff.
  • + 9
 @hifiandmtb: spent way too much time on there.
  • + 1
 @sxy-slo: I have the Rallon with the coil shock on. As I'm not doing too much jumping ans stuffs I don't find it an issue. Now on jumps I bottomed out really bad only once. It was not even a huck to flat, but a huck to uphill, so it was to be expected with any shock.
The only issue I have is it's probably overdamped. It was definitely the case with the DPX2 (even with the lightedt of tuning), and much better with the X2 (medium tuning for compression, I may go for a light as it's fully open).
  • + 5
 @sethius: me too... Pablo took a long vacation though
  • + 6
 @Lagr1980: glad hes back but i hope he will review non xc bikes soon
  • + 2
 There already is
www.bikechecker.com
  • + 1
 Rallon would be similar. Linear bike which is very easy to bottoming out (and broke rims and spikes) if you want small bump sensibility, and super low bb because of the sag and 336 bb height. Then if you add air or compression you will have a harsh feeling, not easy to tune.
  • + 1
 @Abantos: decent shock with good speed sensitive valving like Cane Creek DB should solve that with no problems. What you describe is just relying on spring curves. That is why there is no point investing in flashy frame when it comes kitted with mediocre shock. Add crappy leverage ratio and you can do your underdamped pogo.
  • + 4
 AN interesting option with the Rallon is using MRP's new progressive spring on whatever coil shock to help counter the relatively linear design. mrpbike.com/products/enduro-progressive-coil-springs
  • + 6
 Progressively wound coils. Problem solved, except for the problems they create for your credit card and long term financial health.
  • + 4
 @ratedgg13: It would help some, but these bikes use pretty short-stroke shocks and as such wouldn't get the maximum effect of the Progressive Spring's ramp-up. The Progressive Springs have a max of 65mm of stroke. Paired with shock of that stroke, a 450lb Progressive Spring spring acts like a 525lb linear spring at 90% of travel. Whereas on a 50mm stroke shock (like the SJ Evo 29 uses), that spring would act like only like a 500lb spring at 90% of travel.

That said, they certainly help!

Cheers!
  • + 1
 @NoahColorado: Did you mean me? Also, @ RaceOnlySprings said they are working on progressive coils for shorter stroke shocks, which I assume would ramp up more quickly.
  • + 2
 @NoahColorado: So you're saying that for a longer stroke (say a 60mm stroke on an Orbea Rallon) you get more benefit, while on a shorter stroke like the SJ Evo you'd get less progression?

I ask because I have a brand new Orbea and have been debating putting a Hazard on it with a progressive spring...
  • + 2
 @WAKIdesigns: I’ve tried both DHX2 and X2 with different volume spacers, rebound and compresión settings and tire pressures but most of days I’m not happy with the feelings. With 5 spacers it’s still very linear and overall the bike has a harsh feeling. I have a 170 fork in the lower setting, so reach is 445 and I’m 1,80. I think enduro-mtb.com did a good review
  • - 1
 Blah, blah...words,words,words...

I wonder why I never got to junior year???
  • + 3
 @ratedgg13: precisely. The closer you match the shock to the Progressive Spring's max stroke, the more you take advantage of it's benefit. All compatible sizes get some effect, those with 63 or 65mm strokes get the most.
  • + 5
 @rollbretzel, @waki, @Abantos

The main issue with the Rallon and so many "superbike" like pivots, SC, Ibis etc... is their high AS/PK values.
Most of them try to balance high PK values with linear ratio and coil in order to get less forces counteracting suspension compression in the travel, but they mostly results in what you described : a harsh ride. Nothing to do with the shock. Only high PK consequence.
The only solution is to use a bigger front ring to decrease AS/PK.
That's why a lot of companies mostly communicate on their AS value, never on PK, cause they are strongly positively correlated.
Some companies still thinks that people wants bike that climb like a hardtail, even for enduro bikes so they boast the AS in detriment of suspension action.
  • + 6
 @gnralized: because journalists keep saying that they don’t need a lock out it’s not going to change any soon.
  • + 1
 @gnralized: I’m not a suspension guru, so I based my opinions on my experiences and I totally agree. I have a 34 while some of the fastest in my country are racing with a 30 to make climbs less hard
  • + 3
 @NoahColorado:

Lotsa riders long shocking these so progressive coil could be a legit option.

Also maybe long shock with a high end air shock. I’ve found without a fairly adjustable shock that Spesh bikes can be pogo sticks. My Stumpy does well with a Topaz. Sag in upper 20s plus lotsa spacers for bottom out plus air spring curve chamber maxed at 200psi. Still kinda mushy on the pedals tho.
  • + 3
 @WAKIdesigns:

Good point Waki. Even on my Ripmo demo I toggled between med & firm LSC on the climbs. Loved how throwing in pedal strokes while descending equaled acceleration though! (Open LSC). Something I’m not used to on the Stumpy.
  • + 6
 @WAKIdesigns: I also blame @mikelevy for most things. Smile
  • + 2
 @brianpark: I heard it more often from Mike Kazimer...
  • + 1
 @gnralized: I bought the Rallon mostly BECAUSE of the high AS value. I have had zero issues with the PK, even on the few gnarly descents I've done on it (3 weeks of testing in BC starts tomorrow...). But then, I'm using the DPX2, not a coil or even the X2.
  • + 4
 @gnralized: I totally agree, and all guys with high AS bikes should do a dh fun chainless hahahahahha. That would open some eyes. That said, I had a knolly warden for couple years and that platform is unreal in descents, but the very low AS sucked for flat uphil punchy bits on a race... Fun as fu*% going down though
  • + 1
 @Lagr1980: Dan Roberts also seems to think, that Antisquat is more important than low kickback or the pedals/chain blocking the suspension on descends. even though not all antisquat comes from the chain, the antisquat which does, kinda kills your suspension in my opinion. i always had bikes with around 100% antisquat, the new one is designed to have 0 antisquat in the descending gears,eventhough the shock is not really there yet the suspension is better than on any other bike i have owned. as a tradeoff antisquat in the middle gears is only about 50% and sucks on punchy climbs in between.
  • + 4
 @Ploutre: you need to look at the ext storia with the hydraulic bottom out adjustment. Independant control of the end stroke.
  • + 1
 @MattInNZ: There are very few shocks with hydraulic bottom out, and those would definitely be more suited (the EXT, Fast Suspension, and BOS Stoy Rare, as far as I know, are the only ones with that feature). I would still prefer an air shock on those bikes Wink
  • + 1
 @hamncheez: The main issue with progressive coils has always been that they have tons of manufacturing fluctuation in their spring rates.
There was just no way of consistently making them to spec. At least at the price point where they are an option for mtb.

It would be great if MRP have somehow found a solution, but I wouldn't bet on it.
  • - 5
flag duzzi (Jun 14, 2019 at 7:39) (Below Threshold)
 I just don't understand why people still use the Horst Link ...
  • + 5
 @duzzi: because you can pretty much do anything you want with it
  • + 2
 @WasatchEnduro: agreed, the Topaz really helped out my Enduro. The firm compression position doesn't fully calm the bike, as that shock doesn't have a preloaded shim stack, but it does enough. But the smoothness of the air spring and the rebound tune seem to match the frame really well; much easier to tune than the stock Monarch rc3, even with the debonair can added. I usually run the Topaz in the middle compression position while descending, probably due to the high and linear leverage ratio, but our trails are also faster and smoother.
  • + 1
 MRPs progressive coil springs: mrpbike.com/products/enduro-progressive-coil-springs

They go as short as 51mm stroke, and at 51mm you get about 18% progression. Obviously the longer strokes get more.

Anyone know how that compares to various air cans? Also, is that pricing and weight good for a coil? Its been so long since I sold the DH bike that I don't know anymore.
  • + 2
 The Rallón is a single pivot in which the pivot stands clearly above the chainline (would probably line up with a 38 or 40t chainring), so anti-squat is higher than most bikes and always above 100%. A clear contrast to the Specialized in pedalling efficiency.
  • + 2
 @gnralized: The latest 50+ teeth cassettes allow a larger chainring, so I'm really fine with that. Anti-squat still won't go below 100%, which is optimal. To hell with squatting.
  • + 1
 @ratedgg13: is there force/travel graph for said shock?
  • + 0
 @Abantos: looks like you need a volume reducer or two..
  • - 2
 @WAKIdesigns: your post doesnt maje any sense.. go fck your wife instead of typing bllsh11t
  • + 1
 @NoahColorado: rallon has shock 230x60mm thats nowhere near dh territoty but also not small.
  • + 2
 @sxy-slo: and what do you think you are doing here writing short sentences with typos, tryimg to appear as a mysterious expert? Social media is a nut too hard to crack for you? Take a shower, apply your best cologne, prepare candles, maybe flowers and... fk yourself. Extra soft and parfumed toilet paper. Do it well
  • + 23
 Very interesting. Appreciate the numbers.

I own the alloy version of this bike and have sunk a lot of time and effort into turning it into my ultimate do it all machine.

Some of these stats make sense, some I don’t relate to at all.

From my experience, the stock dpx2 is no good for your heavier rider. Not enough rebound. Small bump sensitivity very poor.

I then moved to a cane creek IL coil at 57mm stroke. This gave the bike 163mm of travel with nil clearance issues. The bike was all the sudden the magic carpet ride I was after. However as the charts suggest, the progression at the end of stroke meant some bottom out moments and using a bit too much travel on square edge hits. Winding up the hsc helped however.

I went back to air, this time a Cane creek DB air with 55mm stroke for 154mm travel. Small bump sensitivity was nearly as good as the coil, mid stroke was fine and with just a single big band inside the air can enough bottom out control to be what I was looking for.

A fox x2 apparently fits by a bees dong. I think this is the ultimate solution for this bike.

TLDR: sick bike, insane geo, shitloads of fun. Put a big can air shock on and enjoy!
  • + 2
 Interesting you mention the DPX2 not good for heavier rider and no rebound...one came on my '18 Transition Scout and the bike lost it's pop and liveliness from previous generations....I swapped fork but also am running no tokens in the DPX2 and it seems to have a bit more life in the back(I haven't been able to get much trail time due to a couple injuries). It almost seems too planted and cushy. I've considered swapping to maybe an RS shock.
  • + 2
 @GlassGuy: tried everything shy of shimming in. That included cutting the travel spacer to make it 55mm stroke, lots of different sag setups and volume spacer arrangements. In the end the rebound dial was always closed.

Coming from a downhill background I was comfortable with the “glued to the ground” feel which I couldn’t replicate until I changed shocks.

It’s more a preference thing than anything but on mtbr forums were there is a big community of us on these bikes, the bigger lads all had the same complaint. A lot of us went Coil and have been very happy.
  • + 4
 @GlassGuy: Why would swapping the fork give the bike back it's pop? As far as I can tell the Transitions are designed to run a lot of sag and use a shock with a lot of progression to give the rear end it's pop. Running 0 tokens you'd end up with a less progressive spring and would need to run a lot more air to get anything like a similar feel and it wouldn't be how Transition recommend running it.
  • + 1
 I demo'd the air shock version of the non-evo stumpy, and it felt pretty good. Couldn't say how it rode the way it did but it felt predictable, good for building confidence, didn't set my pants on fire with excitement though. Assuming similar kinematics with the more reserved geo would explain exactly why. Good article, needs more science-kitty.
  • + 19
 Pinkbike is really feeling themselves these days. First the Megatower review which is as close to a rip job bike media gets in these days (still might cost them a trip to the next launch in New Zealand if Santa Cruz is in a bad mood)

Now they are ripping the big S with detailed analysis of why they are good for entry level riders and people who think they ride hard but really don’t. (Or maybe this is a way to set up why the new Enduro really is a big change...)
  • + 20
 Entry level riders and people who think they ride hard but really don't. That's 90 percent of the market at least. Specialized knows that, and that is why they design it like this.
  • + 7
 @ak-77: This is a very very good point. They are not looking to sell to Enduro bro necessarily, just the 90% of the market. Transition can keep the 10% haha
  • + 3
 @ak-77: put me in the 10% then. I'm slow and I know it
  • + 20
 I wouldn't say this article is ripping Big S at all. It's a very good and detailed analysis of their suspension design. What people need to understand, is there are pros and cons of every suspension design because you can't manipulate the physics.

Pros of the design: Linear leverage ratio so the suspension is very active, great climbing sensitivity because the low levels of anti-squat, great braking sensitivity because the low levels of anti-rise.

Cons: Linear leverage ratio so you have to run higher spring rates or a more progressive shock, not a good pedaling platform because the low levels of anti-squat, poor braking traction because the low levels of anti-rise.

Notice that there were pros and cons drawn out of each characteristic.
  • + 7
 I appreciate Pink Bike going out on a limb and not fearing manufacturer retribution by giving balanced and honest reviews. I survived the Mountain Bike A(Fi)ction days when the MBA editors were just regurgitating manufacturer slanted marketing speak and lore. Pink Bike looks to be presenting a non-biased platform in the interest of us consumers. Like any technical equipment review, the reader should be exercising critical thinking when processing the information and opinions presented.
  • + 1
 @ak-77: spot on lol
  • + 12
 @wibblywobbly the Santa Cruz crew are good folks and in our experience they're not insecure about a fair review. In general the industry respects that our job is to give readers info, and understands that we try to be as fair as possible with reviews.

In terms of this story, please keep in mind that it's NOT a traditional review. Kinematics are important, but not the be-all end-all of how a bike rides in the real world. Lots of other factors in what makes a bike good or bad.
  • + 4
 @tgent: NailD R3ACt 2 pLAy thinks it can break the laws of physics by sheer marketing force alone!
  • + 1
 @tgent: You're correct. Each suspension design has it's pros and cons.
I wouldn't say 50% anti-rise is bad, it just means that the suspension will push a bit to the ground under braking, and that you have to acount for it and adjust your body position.
  • + 2
 @hamncheez: Lol, very true. I hate that damn thing just because the marketing dept.
  • + 1
 one of the best articles on suspension: enduro-mtb.com/en/mtb-suspension-systems
  • + 3
 I'm not an entry-level rider, so I must be one of those who think they ride hard but really don't. But damn Specialized makes a solid bike. I've ridden Specialized for the better part of 20 years. Switched to a different bike last fall, just because I wanted to try something new. The new bike is better overall, but the 2010 Enduro I replaced wasn't that far behind -- probably still plows rocks better than the new one.
  • + 12
 Very cool analysis. I like the way it's cold engineery style. Checking the numbers will end up actually informing us, the riders and weekend hacks, of which i very much am, about how to improve our bikes set up. I'm a fan after two articles
  • + 10
 yep, cold (sometimes) facts are what industry is missing, and pinkbike too since Aston left.
  • + 10
 @Mondbiker: Aston wasn't cold- he let his personal bias cloud most of his reviews- if you agreed with his preferences you liked them- if you saw through his smoke screen...then you didn't. This review- is pure science and it is awesome! Love the new direction Pinkbike!
  • + 2
 @brappjuice: not really, just because you don´t agree with him doesn´t make his reviews any less factual. One of the guys who actually tried to understand why short steep bikes don´t work too well and found the answers. Glad he has got new dream job for himself.
  • + 1
 @Mondbiker: working as a demo rep for Nicolia- after being the European Editor for Pinkbike...yeah ok..
  • + 12
 Since the bike has such a low BB, a nearly liner suspension curve, and 138mm of travel with such agressive geometry, it's seems to have been designed with "over-springing" in mind.
Instead of having 160mm of travel, and having used up 65mm when at 30% sag, you have 138mm, and use 35mm at sag, and still achieve the same BB heigth and amount of usable travel as the bigger travel bike.
I guess the purpose of all this is to make the bike feel just as comfortable as a big travel bike, but also less planted, aka a nimble bike, that can stilll plow.
  • + 5
 I have this bike and you are correct. It only has 138mm travel so you have less to work with. BUT, It is the fastest funnest bike I have ridden. I came off an 2018 enduro with a float X2 and the rear actually feels better on the EVO . You can analyze it all day ,,,,,but it rides up and down really well. I have taken 30 secs off many Stava Segments up and down.
  • + 1
 While the theory is correct, your numbers are very wrong and misleading. A 160mm travel bike at 30% sag will sit 48mm into its travel. A 138mm travel bike at 30% sag will sit 41mm into its travel. Only a difference of 7mm, and the BB on this bike is lower to make up for that difference.

Compared to the Megatower for example (just taking it because it's another 160mm travel 29er that was reviewed yesterday), the BB height (in high) is 343mm and at 30% sage would sit around 295mm. The Stumpy's BB height is 328mm and at 30% sag would sit around 287mm. Again, only a difference of 8mm, though the Stumpy is lower, which confirms the low feeling of the bike.
  • + 2
 @tgent: A 160mm, progressive suspension curve bike, at 30% sag will not sit 48mm(=160mm*0,3) into it's travel.
That would only happen if the bike was completely linear, making 30% of shock stroke equate to 30% travel.
Since most bikes nowadays are quite progressive, 30% of shock stroke equates to more than 30% travel at the rear wheel.
Maybe tomorrow i'll try and work out how much travel 30% of shock stroke is on a bike with 160mm travel, that starts of with a 3:1 ratio and ends on 2:1. (Too busy rn studying eletricity and magnetism for tomorrow's exam)
  • + 11
 Great to see someone take a well deserved shit on shock extender/yoke things. Between ten or so of the new gen Enduros that I know of that were sold through my work we had a 100% failure rate on the monarchs. If we warrantied them through specialized the customer would get a rebuild or sometimes a new shock. If we warrantied through SRAM they'd refuse it and say it's the frames fault. I think the average was about 2-3 shocks per bike, with one guy going through 6. Chatted to the rep about it once and he blamed it on rockshox.

Important bit: if you own an enduro and have shock problems, Specialized will send you an ohlins STX after the 2nd or 3rd time, if you call up rider care directly. These seem to hold up much better. Love them or hate them Specialized are pretty great with warranties.
  • + 15
 Between Cathro and this Gwin has nothing on me
  • + 5
 very cool article, i would like to hear more about that "antisquat without a chain" thing though -from my understanding antisquat relies on the chain to counteract the suspension from compressing. without the chain there is zero antisquat, zero kickback and zero influence on suspension (which can be a good or bad thing ; gwins and R. athertons chainless runs spring to mind)
  • + 3
 Iff you use a e-bike rear wheel and drop the chain, you will have 0 kickback but there would still be more or less antisquat, depending on geometry and CIR location.
  • + 1
 @faul: why ? how much ? explain ? and why e-bike?
  • + 5
 @optimumnotmaximum: E bike rear wheel was the only way I thought to put power on your bike without a chain.
Antisquat occur without a chain because the acceleration force the ground have on your tire will exerce a torque on the swingarm. This torque will oppose squat. The higher the instant center of your suspension, the more antisquat it will have.
  • + 1
 I think addresses this question in the prior article introducing the series
  • + 3
 @gtill9000: not really, he just said there is antisquat without a chain although most people think it comes from the chainforce -this explains nothing.
  • + 1
 @gtill9000: sorry you meant in the comments -i see, although i am not sure if i yet understand
  • + 4
 Anti-squat comes from any tire acceleration force, not just chain tension although on bicycles and motorcycles this is a good way to visualize the impact. The tire longitudinal acceleration force acts to create a moment about the rear axle in the suspension.

For bicycles (and motorcycles) the chain forces are relatively large and create a counter moment (torque) about the rear axle that causes the shock to either sag (think High Single Pivot without an idler) or extend (think about having a giant cassette cog and how the chain would pull the wheel down). This adds or subtracts from the moment created by the tire force and the total result gives you the anti-squat number.

On a bicycle its pretty damn hard to accelerate the rear wheel (without using your hands) with no chain so there is effectively no anti-squat effect without it. Note that acceleration due to gravity does not have the same impact because there is no force on pushing on the tire (which is what is creating the anti/pro-squat moment).
  • + 5
 Real world experience with the Evo is very different. It isn't the most plush machine I have ever ridden, but it pedals very well and rarely bottoms out. I know keyboard jockeys will say that I don't ride hard enough, trails aren't steep or rough, blah, blah, blah. Obviously I will disagree, but I know for sure this is one of the best suspension curves/setups I have ridden. Truly one case where the numbers don't equate to the ride.
  • + 4
 I would say, from my feeling, that this is the same trouble at many Specialized bikes from old SX trail, over Enduro (last ridden version 2016) to Stumpy, lots of tokens in air can or just massive coil/over pressured otherwise it is rocking the bottom pretty often and eating so much energy instead of using it
  • + 4
 I was thinking SX trail too! Super linear, but actually worked pretty good with the fox DHX shocks of the time. I think I had to run like a 700# spring though
  • + 2
 @skerby: I´ve been riding one top spec. whole summer 2017 in Solden with DHX rc4 and yes it worked pretty good when the compressions has been set up correctly and the more important, the bottom out almost totally closed, but honestly the spring I´ve been using was something like 650lbs for my not even 80Kgs in gear which is crazy
  • + 2
 Specialized often uses shock stroke reducers, at least they did in the 2014-2016 enduro shocks. I removed mine and that changed the stroke from 57mm to 63 and travel from 165mm to ~183. With the spacer, volume reducers weren't as effective and I had to put a lot of them in my cc il to get some progression. Now I can use way less
  • + 1
 I went from a 2011 Enduro to a 2018. They are very different. I run a lot of rear sag 35% plus. No bottom out even on horrible flat landings and pedal bob under power when standing is minimal. My old bike ride low and eventually a pedal strike OTB killed my collarbone. The 2018 bike is way better.
  • + 1
 @headshot:

which rear shock?
  • + 1
 @WasatchEnduro: the 18 has a Monarch plus RC3. The old one had a Float. I'm sure the shock makes a lot of difference. My point is really that IMO the enduro has improved and Spesh have moved with the times albeit slowly. The 18 enduros and onwards were specifically designed to be less linear than the 17 model. That said I've never ridden the latest crop of monster trucks so I may be way off....
  • + 4
 "Moving the chip to the high setting gets rid of a touch of that end stroke linearity, but now introduces a bit of regression at the beginning of travel. While it’s not at all a big amount of regression, 0.7%, it is taking a step down the road of potentially creating a problem for the damping continuously going back and forth over this hump and the changes in shaft speed that it brings."

This doesn't make sense. This regression you're talking about is tiny and only in the first 7-8mm of the stroke, so at sag it's not affecting anything, and I doubt it will ever be noticeable. Damping is not going to go continuously back and forth over it.

Thanks for doing this series though, it's really valuable to have linkage analysis. After this you guys can try nerding out over tires.
  • + 2
 While riding, the rear end constantly goes back and forth across the sag point as it tracks over bumps (positive travel) and extends into dips (negative travel). Not to say I’d be able to feel that 0.7%, but the tiny ports and pathways in the damping circuit could be sensitive to it.
  • + 1
 @DRomy: the sag point is well beyond the regression
  • + 6
 I'm pretty sure 99% of people who buy an Evo don't buy it based on shock curves, but because it looks RAD as F###
Raw carbon and raw aluminium for the win!
  • + 1
 And a big part of them won't ride a track that'll show the limits of a quite linear curve so they'll be happy. Others will fix it with tokens. 1% of them or less will ride too hard on too demanding tracks to obtain a perfect bike but as it's not a bad bike, they'll be happy still... Until premature bearing maintenance.
  • + 1
 @faul: I'm currently scratching my head to make the suspension feel better. It's really not at the frame/geometry performance level. Probably send fork and shock for revalving.
  • + 1
 @fracasnoxteam: What's your issue?
Revalving your suspensions is always beneficial.
  • + 1
 I do
  • + 1
 @faul: issue is written here: rear suspension sucks.
  • + 4
 Judging ride quality from the numbers is like using a crystal ball. I rode the stumpy evo last weekend and it was great. Period. (no, I'm not the owner)

I'd ride the bike to find out if there is something in the feel of the suspension that stands out. Only then check the numbers and see if there's an explanation for it.
  • + 3
 specialized must have some knock off crystal balls eh?
  • + 14
 @Mondbiker: They are proprietary crystal balls by Specialized.
  • + 2
 I have stumpy (non evo) and everything written in the article is true and I have "felt" it out on the trail.
The worst thing is being stuck between bottoming out all the time and having to run less sag which makes the bike tall and shit in the corners.

So in a way you can judge the ride by the numbers (they are what is defining the ride in the end), but of course you shouldn't get too hung up on them.
  • + 12
 @Upduro: S-workavski Crystals.
  • + 2
 @Plancktonne: I have a non-evo stumpy and have had very good luck with a slightly overshock (52 mm) and a little bit of volume reducer in a Cane Creek Air IL. Also overforked it to 160. There is indeed a magic place where you can use all the travel but not feel it bottoming out. Plush and planted, still loads of fun on the hops. Hope you find your happy place on it - still my favorite bike to date =)
  • + 2
 And that is exactly what he says in the first paragraph of the intro to the behind the number series. Numbers alone do not tell the story, nor does ride feel alone. By combining them, you can better educate yourself on explaining what you are feeling and then understanding why.
  • + 2
 @Lokirides: that's actually what I'm debating at the moment, the DVO topaz i have now is great but the sweetspot for my weight and riding is not there, so I was thinking of picking up longer stroke CC air. I'm already 160 in the front.

The bike is great, bit short for me but otherwise crazily capable and fun. Everything from backyard trail, long xc rides or DH lines in park. But putting yet more money towards trying to fix it or just buying new bike .... But I think you just broke me xD

Thanks for the tips!
  • + 1
 You can extend the 50 to 55 on the dvo, it’s the same shock. Also, while the cane creek has a few more dials, I find the topaz easier to get dialed. Better access to the volume spacers, the negative chamber, and the topaz rarely heats up (I’ve had the cane creek heat up too much many times). On a short stroke shocks, and bikes that use travel quickly like the stumpy- I think shocks will overheat easier so this is really important (to me). I’m having a good time on my stumpy evo, took a while to figure out the tune, but I can definitely feel everything they say in the article. @Plancktonne:
  • + 3
 People who like nerding out about all these numbers should check out AndreXTR on Youtube, he's got a whole bunch of videos calculating suspension kinematics. Unfortunately he doesn't seem to upload anymore, but they're fascinating videos nonetheless
  • + 4
 Thanks Smile Cheers
  • + 3
 @pinkbike
I really enjoyed reading that, and there are a bunch of really interesting comments on this article. Would you consider adding some additional factors into the conclusion along the lines of some of the comments?

XYZ type of shock would be likely to work well with this linkage arrangement. Coil shock, air shock, one with high and low speed compression/ rebound adjustments etc etc etc

ABC type of tune is likely to be required to get the most out of this bike. Maybe link this with the below comment if applicable.

Whilst it is not explicitly mentioned in the assumptions section of the behind the numbers article I am assuming that the number used for centre of mass is an average number of Joe MTB at 75-80Kg. My limited knowledge on this has me thinking that if you are a very light rider or a very heavy rider the impact of the various curves is going to affect you and the setup of your shock in very different ways.

If this is correct (I appreciate I may be way off the mark here) could you comment if the type of set up being analysed is likely to suit and or hinder a particularly lightweight rider or a heavy one. And maybe if a lighter than average or heavier than average rider would need to consider more than simply air pressure/ spring weight changes to get the most out of the bike.
  • + 3
 2019 29' evo pro owner. Numbers are awesome, thank you. In reality, for me, all these bikes are 1000x more capable than me. I love the feel and stiffness of the new bike. Doesnt seem to blow through the travel and is surprisingly poppy. She tracks straight and true in the rough stuff. I bought the bike as my park rig, turns out its a monster on the trails and mellow stuff. She does shine when the going gets rough though. Overall im stoked.
  • + 3
 After 20 years of riding different bikes, I am yet to meet the Brake Jack, Pedal Bob (with locked out shock) and Pedal kickback, yet I met so many midstroke hoes that don’t use full travel and harsh tight Johnsons with surprising bottom out prospects. All Spec bikes I rode with decent shocks were good.
  • + 2
 Take a run down something gnarly where you are using all of your travel. Then take off your chain and do the same thing, you will notice how free your feet are and you'll meet Pedal Kickback. Brake Jack is harder to notice because you essentially can't get rid of it without changing the bike, but riding a bike with high levels of anti squat then a different bike/suspension design with low levels of anti squat and you'll notice how much more firm the suspension is when braking heavily, you just met brake jack.
  • + 1
 And naturally I mix it up. Meant Anti-Rise.
  • + 1
 Having owned 2 bikes with brake jack kits and ridden with and without them mounted, it's noticeable, those trusty old single pivots. Pedal Bob is noticeable with the x2 on a different bikes, the wish was a prime example.
  • + 2
 Stock tuned coil shocks were too linear for me on all my SJs (I have had 9). They had too much lsc and not enough hsc . They felt awesome after I tuned the shock for the way I ride and the leverage curve. A stock tuned shock is just that, a stock tune. It's not going to work for every single rider. If you are more than just a weekend warrior than any stock tune on any bike will feel underwhelming to you. A coil shock paired with a not so progressive or regressive curve will be an odd pairing for any aggressive rider without custom tuning.
  • + 2
 FWIW, Linkagedesign has a very different leverage ratio curve listed. Yes, its for the non-evo but it should be very close (same travel, same kinematics layout). They see it going from 3.1-2.65 - simple math shows a 2.76 overall.
  • + 2
 Seeing a lot of comments about it not being fit for heavier riders; seems to make sense since I run 200-210 PSI (i'm about 170 pounds ish depending on the day) in mine.. I have yet to have any harsh bottom outs, bike is quite honestly next level .. I can't imagine riding anything else at this point.
  • + 2
 Funny that every person who has ridden the Evo thinks it’s the best thing since the coming of Jesus and those who haven’t don’t. I was super sceptical but rode the alloy and bought the carbon.
For the record I’m 148lbs and run the stock 550lb spring; so it’s way over sprung. I thought the air shock (on the alloy) suited the bike more and will probably swap to one.
  • + 2
 er you can make a coil spring progressive by changing the pitch of the winding or by adding a decent bump stop, why isn't anyone doing this? I ride a coil because i'm heavy & the high air pressure i have to run in a air shock reduces it's initial small bump performance, plus a coil is a bit more fit & forget once you've got a rate that works..................
  • + 2
 Mrp does
  • + 4
 MRP are selling progressive springs now - with a 50-80lbs higher strength at end of travel . from what i gather they are all 63 mm stroke with differen lenghts - so possible will fit only 200 i2i and above EXT shocks are using an hydrolic bottom out -- i think that is the best solution to get a ramp up at end of stroke Manitou uses some hydro ramp up on the Dorado style air spring - works golden for the forks as well
  • + 2
 @zemaniac: Tried a rental dorado that i disliked but that "hbo"! Best feature of this fork. Feels way better than tokens.
And after trying the mattoc of a friend, I need that HBO on every fork now. Mattoc is at the top of my wish list for my next fork.
  • + 4
 I'm running an MRP progressive spring on my Mondraker Foxy 29, a bike that "by the numbers" should avoid coil shocks at all costs. Paired to a modded and custom tuned Marzocchi Bomber CR the result is absolutely mind blowing. It has a longer progressive bottom out bumper as well.

The harsh AF ride that I had with the DPX2 has given way to a supportive yet smooth ride with insane amounts of traction. I also tried a Float X2 which was a bit better than the DPX2 but felt kind of dead no matter how it was tuned. Progressive springs absolutely work.
  • + 1
 @mtbgeartech: what stroke / i2i are you running ?

was thinking of getting the Marz as well
  • + 1
 @faul: i was running the dorado few years ago on a spec demo 8 -- actually really liked it .
but i'm only 70 kg - i think heavier riders might struggle with the dorado
  • + 1
 @zemaniac: I'm even lighter than you.
It's not that it was a bad fork. It's just it was really supple at the top and I like forks with much more support. And I didn't spend enough time to know what to tune to obtain a better feeling. Pumping up air to max and closing every knobs didn't help much.
Mattoc on the other hand, which is claimed to have "dorado internals" is quite different and suits me better.
  • + 1
 @zemaniac: Are you on the Foxy 29 too? I have the 205x65 Bomber CR. The extra travel is no problem on the Foxy, no clearance or binding at all even with the stock bottom out bumper. I would recommend a longer bumper though as the end stroke is regressive.
  • + 3
 @zemaniac: Mattoc (adjustable), Minute (fixed, new models) and Mezzer (fixed) have HBO as well. I think it is a great feature that should be more widely implemented if suspension companies really care about performance.
  • + 1
 @mtbgeartech: no , i have an evil calling . it's a 50 mm stroke ( can fit a 55 as well - and get an extra 10 mm travel) . i'm still unsure if the short stroke coil will be suitable .
did you need any adapter to fit the MRP spring on the original collar ?

the evil is progressive up to around 40% travel , then quiet linear with a small ramp up @ end of stroke
i feel a progressive spring will be needed
  • + 1
 @mtbgeartech: Wish we could swap shocks for a day to compare your Bomber as I'd like to compare to my Avy RT3 from my own Foxy.
I agree that the stock DPX2 was pretty awful on this bike.
  • + 1
 @zemaniac: While an adapter isn't absolutely necessary having one does make the spring fit a bit better.
  • + 1
 @SunsPSD: That would be fun. I'm sure your's is awesome. You've got the benefit of adjusting spring rate and a more progressive rate which I'm sure is nice. If I can get my hands on a take-off or used one I'm going to jump on it.
  • + 1
 @Mac1987: mezzer details are non existant since its press release. I'm waiting for it, and if there's a coil version of the mara.
  • + 1
 @sethius: yes, I'm waiting for reviews myself. I've heard or read nothing about coil versions of the Mara though.
  • + 2
 @Mac1987: I'm just living in hope for one. It would make life easier than trying to pick from ext/motion or mrp.
  • + 2
 I got an older stumpy evo, and most of the short falls can be helped. Pedal strikes, yep. I put on shorter crank arms. Yes it bottomed out on 2” drops. A Push industries shock helped. Bobs when climbing it did. I flip the switch on climbs. I definitely increased the cost, but with a 160 mm Pike up front, this thing handles most everything now.
  • + 2
 This writer seems to know what he is talking about , however ,I believe you should take it with a grain of salt because it is a very enjoyable , very intuitive bike to ride .This would most likely feel at home if you enjoy DH bikes
  • + 2
 I'd want to see numbers analysis versus riders notes.

I'm a SJ evo 29 rider with a coil @52.5mm stroke, flat pedals, aggressive ex bmxer with a strong preference for pumping whenever I can.

I was hesitant to put a coil on, it's least least progressive leverage rate bike I've ridden in a while, asked a sponsored rider with the same style who was running coil on theirs, they said go for it, so I did. Feels great to me. Do I bottom out, yes. Do I care, no.

Numbers say neutral bike in terms of pedalling and kickback, agree with that, been put off masses of anti squat on previous bikes.

As in the other intro post, there's mention of feel versus numbers and importance but not seeing it being implemented here.
  • + 5
 www.pinkbike.com/news/review-specialized-stumpjumper-evo-29.html
The bike review does not seem to echo what the analysis states.
  • + 2
 @SintraFreeride: this one does www.pinkbike.com/news/first-ride-specialized-stumpjumper-evo-pro-carbon.html
And if Kazimer has to ride 600lb spring, gl to anyone else with bodyweight 20-30lb heavier, that shock is going to work overtime all the time.
  • + 1
 @Mondbiker: I am 230lb and use a 600lb spring on mine. But have hsc wound up a bit. Works out to be 32% sag.

He would have been riding at like 15% sag with his light bones.

650lb was too harsh for me.
  • + 2
 What does this tell us in a larger context. For example, I found this comment "Pumping the bike will result in more energy going into compressing the shock rather than maintaining forwards momentum" to be how I feel about the Spec FS bikes I've ridden; they've always felt wallowy and I feel like I'm fighting to move forward.

So given that I don't get on with Spec's Horst-link and given the "numbers" on this Specialized, what should I be looking for in a bike??? Higher leverage? Over 100% anti-squat?

I've really liked Yeti's SI and Pivot's DW...should I just stick with those b/c numbers are meaningless????
  • + 11
 From my experience riders either prefer four-bar or dual-link...I am in the four-bar camp, even though I currently ride a dual-link bike (VPP). One of my closest riding buddies is in the dual-link camp and is currently riding four-bar. Everyone's impressions are going to be different because everyone prioritizes the billion factors involved differently.

One thing's for sure though - Specialized's FSR suspension has endured as one of the top suspension formats for over two decades for good reason - because it's awesome. It's noticeably plusher than dual-link while descending and what it lacks on climbing can be fixed by a good shock. You can't say that about suspensions with built-in anti-squat...that anti-squat has a detrimental effect on active-ness that cannot be turned off, whereas you can always turn off a shock's compression damping.

VPP works well for me because climbing is where I need the most help. I can handle the harshness while descending at mach chicken because I need all the help I can get when the next climb comes along. Also, dual-link has this "popiness" about it when it comes to jumping...it's a suspension that loves to party. That "fun" is missing from four-bar suspensions.

My recommendation is always this - if you want your suspension to be descending focused, you want four-bar. If you want your suspension to be climbing focused, you want dual-link. If you love to jump off things, you want dual-link (especially DW-link). There are billions of other factors but in my experience, those are the most noticeable ones.
  • + 2
 @TheRaven: There you have it. I enjoy climbing and I hate a sluggish feel when going up. And I don't mind a less plush feel when descending esp. if the plushness comes at the expense of climbing acumen.
  • + 3
 @TheRaven: I upvoted your comment but there is one other scenario - If you are tech climbing focused, then you want that 4 bar compliance while climbing (at least I do). One reason I don't tend to link dual link bikes and other designs that prioritize anti-squat is when you are under power and need that last 1% of traction, the same forces that are "locking out" the sag are reducing traction.
  • + 4
 Reading this review it seems the bike is a pile of crap. But then you read reviews based on people riding it and they say its really fun. Which one is it PB?
  • + 4
 It's a really fun bike, but there are some aspects of the suspension that could be improved. As Dan's analysis notes, it's a bit too linear given its intended use, but that can be worked around - extra volume spacers in the air can, a higher spring rate with a coil spring. Numbers don't tell the whole story, but they can help quantify what a rider is feeling on the trail. The EVO is still one of my favorite bikes in recent memory - it's far, far from a 'pile of crap.' I'd recommend giving one a test ride if you get a chance.
  • + 0
 @mikekazimer: Great work. I've been saying this about bikes for past few years and didn't like the Enduro or Stumpjumper for the same reason. Linear progressive is the way to go, reliance on the air spring (and volume spacers) to create damping force is a bad idea. Let the damper do the work - it's way more controlled. The stumpjumper is good if you aren't riding it hard...great parking lot feel but very difficult to get settled during high speed impacts, BO impacts and balancing that with small bump.
  • + 1
 @mikekazimer: Maybe pile of crap was a tad strong! I have test rode one, and hit some gnarly stuff, didnt really find an issue with its suspension performance tbh and was surprised how nimble it was. I own a DH bike so arent really looking for one to rule them all type ride

I like the critical review, only problem you guys have is (if we are being scientific) we need similar analysis done on most other big hitters in the trail bike field! Or at least 3 others.....
  • + 6
 @commentsectiontroll, don't worry, this is just the beginning - there are more analysis articles on the way.
  • + 2
 @mikekazimer: I have a dream. A dream of the convergence of engineering analysis, test ride opinions, and empirical data gathered on-trail (can the Shock Whiz or something similar do this?). Let's demystify this shit!
  • + 2
 @mikekazimer: your original review was the catalyst for me getting one. Glad I did! it’s blown me away, only negative is that my downhill bike had more or less sat in the garage gathering dust.
  • + 3
 @Brasher, ha, glad you're enjoying it. This bike is a prime example of how much geometry matters. With a 160mm fork and a little longer stroke shock it gets even more impressive.
  • + 2
 @mikekazimer: done both. 57mm stroke coil shock and 170mm vorsprung coiled 36 up front.

It’s the nicolai for poor people Smile
  • + 1
 I think it’s numbers vs “the real world”. Both are aspects are very relevant.

I own and love my Alloy EVO (650b version) but have noticed that it gets pretty mixed reviews. Try comparing the Vital and Pinkbike reviews, they are very different!

I think that it’s a progressive trail bike as opposed to a light Enduro bike. Reviewers seem to love it or hate it depending on what they are looking for.
  • + 1
 @Brasher: You cannot really compare this to the nicolai/geometron in either geometry nor kinematics lol.
  • + 2
 @Brasher: done the same on mine too, MRP Hazzard running 57mm stroke and Ribbon Coil at 170mm! Next step is mulleting it (I have the 27.5" S3) with 29" 160mm Ribbon Coil up front. Should make it even faster than it already is.
  • + 2
 @andyrm: mullet sounds cool, it I was thinking of 29’ering it (is that a new word?). A 29” wheel with a 2.5 tyre fits fine on the back (I tested it throughout the full shock stroke).

It will lift the bb a little less then 20mm but you could run it in the low setting and fit some offset bushes to try and get it back down a little more as the low bb is part of its charm.
  • + 2
 I always hear of adjusting air pressure to solve dampening issues. The mtb world doesn't seem to want to revalve components, instead preferring to slap on a while new unit praying the OEM valving works for them. Odd
  • + 1
 Interesting. If you follow the specialized suspension Widget on their site it will overspring the rear and I’m my experience equates to about 20% sag. Open the compression a click or two and I’ve found the setup plenty plush but does bottom easily as noted here.
  • + 1
 I just got the Ohlins TTX air made for this bike specifically. First ride, I have never felt so much forward momentum before. Pillowy bottom out, stretched the stroke so I get an extra 10mm of travel and boom; the bike was already my favorite bike ever but now wth proper suspension, and the new 36 on the way, this thing is like riding a dirt bike.

All you Specialized haters need to a find a new hobby.
  • + 1
 I think the Stumpy Evo is a rad bike that doesn't pedal great in open mode, which is a good description of lots of Spesh bikes. Because this sort of geo is so much better than older geo, this bike still garners pretty solid ride reviews. If I lived in a locale where I didn't have to pedal a lot over rough terrain to get to the top of the descent, where instead I say pedaled a fire road or was shuttled and I could lock out the shock for long periods of time, the Spesh Evo would be my bike for sure. I remote shock lock out, or maybe a shock that can sense when it's not descending through electronics and can lock and unlock instantly, would be a nice feature.
  • + 1
 I guess the only other comment I'd make is about anti-squat, I think Specialized has been trending towards higher AS percentages but they were on this philosophy of having low AS combined with shock tricks like Brain for so long I guess they won't change overnight. You should probably note that reducing PK in general should correspondingly improve traction and plushness so there is a tradeoff there. You can lock out a shock for climbing but you can't dial out the AS. Knolly bikes are one of the others who usually go for lower AS. That said, for trail riding it really makes more sense to prioritize pedaling...
  • + 1
 The Specialized Horst link has been around a while, and Specialized is a top brand, so obviously a lot of people like the feel of it. I owned one for a while (not the EVO, but a Stumpjumper), and while it felt plush and comfy, it was a bit wallowy and more linear than I prefer. Great bike, but I prefer something with a bit more progression. I'm assuming it had similar numbers, although I could be wrong.

Keep this stuff coming -- it's fun to geek out and see the numbers behind things. I keep going back to an ABP bike because it feels more balanced for the way I ride. I would love to see an analysis on that and whether the numbers confirm what I feel. I loved my old DW Link 7point7, but there are so many variations on that design now (VPP, Maestro), it would be great to see a comparison of 2 bikes that take radically different approaches to that type of design (link positions and angles). I keep considering going back to a DW Link-type bike, but they are all so slightly different I don't know which one I would like!
  • + 1
 Awesome series. Its great to finally see a review of suspension metrics. I'm curious how much size and shock tune play into this and would love to see future installments answer a few more questions. Could this be better bike for larger or smaller rider? Did they spec the right tune in that size? Could a different tune improve the bike?
  • + 1
 Own the alloy 29 evo for a few months now and really enjoy it. I ride it back to back on the same trails as my demo and holy cow does it carry speed but the second I point it into a burly rock garden I hesitate quite a bit and pick the smoother but slower line to avoid blowing up wheels . This bike is incredibly confident at high speeds and even rough trails but lacks the forgiveness due to the linear suspension and shorter travel but the evo bottoms out like a champ and has never bucked or thrown me off when it does bottom out. I'm from Tahoe and for the local steep but smoother trails I can't think of a better rig. If you love the confidence of a dh bike but don't need the travel the evo is for you
  • + 1
 This is fantastic and excellent analysis! This also excellently explains the general feel of most specialized full sus trail bikes and how they generally tune their horst link suspension. Note that just because this is what a specialized horst link behaves like, you can tune a horst link bike to behave very differently. Spec seem to prioritize anti-rise, pedal kickback, and active suspension over anti-squat which IMO leads to their bikes feeling very inefficient. Also, on the standard stumpy, this linear lev ratio seems right at home, but on the Evo, I wish it was much much more progressive for a more aggressive ride.
  • + 1
 This series is awesome. I'm still of the biase that geo numbers are going to effect ride quality for the average rider more then suspension characteristics. Worked at LBS for some years seen a ridiculous amount of riders who set sag, turn a few dials once and forget about the rear shock all together. Also any bike can be made to feel good with a custom shim stack.
  • + 1
 Really appreciate this article Dan!
Well written and very insightful, really goes over this bikes suspension with a fine tooth comb. I've been looking into getting a Stumpy EVO Pro for a little bit now and while I love the geometry of the bike (mirrors my Transition Patrol), I could never get around the issue with having such a high leverage ratio. As a bigger rider who rides a bit aggressively, I know I'd have to be running a #650-#700 spring and that is just tough for any damper to deal with let alone the sacrifice of small bump sensitivity. After reading through this article and re-reading some sections twice, I'm starting to think the EVO isn't going to be the bike for me unfortunately. But I guess you could always just say f*ck it and just ride the damn bike and be stoked on it, short comings and all.... hmmmm... puzzling.
  • + 1
 Really well written article, the effort and scientific approach is appreciated. However, it makes me want to stick to riding hardtails even more. Have bikes become too complicated? At least we have options to cover every taste..
  • + 1
 I rode one last weekend, except it was full DVO suspension. I left it in open mode and it climbed pretty well. Maneuvering with those big wheels and the overly flat tire profile from too-wide rims hurt it but I can't complain about the suspension.
  • + 2
 When does the contest to name the laser kitty start, PB?

Super articles for the first two ... keep 'em comin' please.

F = m x a. E = m x c squared. W = F x D. Torque = F x radius x sin theta. Etc.
  • + 1
 I generally prefer a stiffer linear setup as opposed to a progressive linkage, I even took all the volume spacers out of my shock, better for control while jumping and gives a more consistent feel over rough stuff, no random bucking off the lips of jumps either, the sacrifice is of course in small bump compliance and more wallowy pedalling.

I have ridden one of the new regular 29er Stumpys down a dh track though and found it had a major tendancy to rip my feet off the pedals over square edge bumps, lost my feet a few times which I've never had happen before on another bike!? Why would that be?
  • + 2
 The kinematics are prone to "double bump hang up". Your suspension is packing up because your rebound is too slow.
  • + 1
 @Sugarbrad: I think it was more to do with feedback from the chain, or maybe the forward axle path causing the bike to hook up on square edges and my feet were slipping due to the sudden jolt, I had the issue you mentioned with my stock fox float shock on my giant, that just feels more like your riding a hardtail when you go over stutter bump sections, the suspension feels like it's just given up
  • + 1
 But it could have been not recovering quick enough and bottoming/locking out that was causing my feet to slip suddenly
  • + 1
 yes the numbers are important but factor in tyre pressure, frame, wheel, suspension & component stiffness/response, plus personal riding style & feel preference's & you still can't buy just from numbers alone..............my mate & I have the same bike but a different suspension tune, different component mix & we favour much different tyre pressure's & it's noticeable that they are very different machine's so a bike design has to be robust to this..........yes you have to get the numbers right, then target the bike to a riding style, but you will still have to do some development riding, fine tuning & re-design (humans aren't redundant yet thank god) & for me a bike always has to have good aesthetics to sell (Marin take note)...................
Great series though, looking forward to the rest...............
  • + 1
 Specialized are very liniar ... never understand really the combination with a steel spring. But it depends much on the tune i suppose. On mine enduro i always used the whole stroke even on small jumps and full with spacer (rs monarch M/M)
  • + 3
 Sounds like a pretty shitty bike to me, unless you're after ultimate 'plushness' and comfort and rarely get the wheels to leave the ground..
  • + 10
 In all fairness plushness vs poppiness when it comes to kinematics is one hell of a bullcrap. Especially in the case of FSR or ABP bikes. I’d love the person stating that certain bike has certain dominating characteristics to handle his bike to me. One click of LSC or rebound does more than some kineshmatics. World is too full of “suspension analysts” who cannot turn their knobs right and cannot ride for sht. Anyone with slightest clue about riding and setting up suspension can adjust their bike to be either plowy or poppy and with a bit of shopping luck and a decent shock he can get quite a lot of both worlds.
  • + 5
 As these analyses only show one part of the picture (which the author notes as well), it would be a mistake to write the bike off based solely on this information alone. As someone else pointed out, this information PLUS actually riding it can help you dial the bike in more accurately to your riding style. And as actual owners have commented, the bike is a lot of fun. Gather all of the data before you come to a conclusion.
  • + 2
 Some people prefer plush and some prefer progressive and poppy. Waki is right though, with the amount of tuning possible on shocks, you can set this bike up to be either, with compression damping or as the author states with higher spring rates. However, different suspension platforms will lead themselves to be better set up one way or another and this definitely leans towards plush.
  • - 2
 @WAKIdesigns: right, let’s put a way harder spring in there and give it loads of lsc to keep the f*cker from bottoming out....at the cost of any form of sensitivity.
  • + 2
 @bonkywonky: lsc effect on bottom out resistance is close to none.
  • + 2
 @bonkywonky: just get a shock with separately adjustable HSC and LSC, preferably separate LSR/HSR, learn to dial it in and come back to me... my 160 Carbon Jack with CCDB has more support, enough plow/pop tolerance and pumps better in open mode than my previous Blur TRc with Pushed Float CTD. Considering the price, that bike s suspension was a piece of crap.
  • + 3
 What happened to the laser kitty? I can't understand any of this suspension mumbo jumbo without a cute kitty explaining it to me Frown
  • + 2
 I also came here for the laser kitty. Please bring it back!
  • + 1
 Interesting stuff! @dan-roberts how do the standard Stumpy and the Levo compare? I've come from a Spitfire with DBair (arguably one of the best 140mm suspension designs) to a Levo (with the Deluxe RL). I notice the lack of brake squat on the Levo and wish there was more like on the Spitfire (which I previously thought was a weak point of these short link designs). The Levo feels good with a lot more sag than the Spitfire, uses more travel but never bottoms hard (but I'm not that rad). The Spitfire's highly progressive linkage had a lot of pop but was harder for someone of my skill to control when hitting jumps. I do wonder if my liking on the Levo has a lot to do with the standard shock tune being a fortunate match for my weight and speed - plus the huge sprung:unsprung weight ratio has to help the suspension work better?
  • + 1
 @danroberts. I have a 2019 enduro 29 with Fox X2. I think the bike has the same dilemma you state here with the trade off of a more supple set up the bottoms out frequently. My question is do you think it’s better to go with a firmer spring rate and less sag or stay with recommended sag and add progression with volume spacers? What are the trade offs? Thank you.
  • + 1
 Play with the spacers a little bit, definitely better to keep the sag and use the spacers, you will probably end on even lower pressure than now. If you are a big guy, don´t waste your time with the smallest one and start with medium or the largest. The trade off is better bottom out resistance, better mid stroke support, better small bum sensitivity due to lower pressure.
  • + 1
 @bok-CZ: better mid stroke an lower pressure don´t go very well together.
  • + 1
 @Mondbiker: depends of the spacers volume I'd say
  • + 1
 @bok-CZ: best mid stroke support will always be with zero spacers because you need to use more pressure to prevent bottoming out all the time, mid stroke is pretty much all pressure dependent, it would require serious volume reduction to alter mid stroke which would effectively turn it into end stroke as you would be bottoming out on air ramp up instead of using full travel. Only way to go around it is to use 3 separate air chambers like in some forks, not so easy to fit those in small shock body though.
  • + 1
 @Mondbiker: on cc inline I had few years back the mid stroke was really a bit stiffer while I also lowered pressure a little bit when going full packed with spacers. Of course it is pressure dependent, but when packed with spacers there is more pressure in the can obviously when pushed to mid of travel
  • + 1
 @bok-CZ: there is video explaining everything about volume reduction from Vorsprung on youtube, look it up, sometimes you cannot rely on what you feel too much, physics are physics.
  • + 1
 @Mondbiker: thanks guys. Sounds like one vote for firmer spring, no spacers and less sag. One vote for same sag and add volume spacers.
  • + 1
 @Stumpjumperevo26: maybe you will end with a lil bit of more pressure, spacer and open low speed compression Smile
  • + 2
 Would like to see an analysis on the Mondraker Foxy, wich seems to be the opposite of this bike in terms of suspension kinematics.
  • + 1
 I stuck a longer coil on mine and opened up the compression, bike feels better. Easy to adapt form a bike with amazing rear geometry to one with an average design, I have both. It's the wheelbase thats no.1
  • + 1
 Longer coil? Just got my carbon evo coming from the alloy with the dpx. Coil didn’t feel as planted first ride as the dpx.
Trying to figure out where I need to go damping wise.
  • + 1
 @elsinore: there is a 5 mm limit spacer under the bottom out bumper. Carefully clip that off and you will have a 210x55 shock that provides longer travel and no change in geometry. This is also applicable to the DPX, but it has to be opened to remove the spacer.

There is no difference between Fox's 210x50 and 210x55 mm stroke shocks beyond the travel limiting spacers.
  • + 1
 Very neat! I thoroughly appreciate the in depth analysis and how it relates to actual feel on the trail! I am very curious to see how a comparison to Yeti, especially the SB130 and Evil, like the Following MB
  • + 1
 Hey Pinkbike, embed these graphs so we can se them live when you push down on the suspension! If you did that, it would ramp up my knowledge haha! See what I just sprung on you right there....
  • + 1
 try downloading the demo version of "linkage X3" by "bikechecker". Many bikes are shown, you can play with them to alterate the numbers.
When you understand the curve, it help understanding the whole bike.
  • + 1
 Head angles are getting well too slack now. The further away the wheel the less weight over it and thus less grip. Glad my bike has a sensible head angle and 27.5 wheels. Ive even been longing after 26 wheels lately.
  • + 1
 It´s a lot more complex topic than that, otherwise my 62deg HA g16 would only go straight Wink
  • + 1
 Been riding an Evo pro for 3 months, went up a spring weight (550 to 600) and it's been awesome - I'm 90kg kitted up. Love how it rides and it climbs very well (with the switch flicked, which I have no issue with).
  • + 0
 I've demo-ridden one of these SJ Evo's. Basically just as the reviews and this analysis says - dead nice and aggressive geo that is happy to go crazy fast, but drops over 2' make the bike bottom out so hard you wonder how many times it could take that before breaking. The one I rode had a DPX2 with blue volume token (which I think is quite big) and 25% sag. A coil shock would be even worse, unless you put a 900Lbs spring in there and made the back suspension mostly redundant
  • + 1
 I'm confused. How does this bike have 138mm of rear travel? All the stumpys I see on specialized website are 150. Did I kiss a previous article where they found it only had 138??
  • + 2
 How do spherical bearings help with side loading of the shock? @dan-roberts
  • + 1
 They absorb the side loads and also don´t bind like bushes do in these situations.
  • + 1
 @Mondbiker: Except they don't absorb side loads. I will say that any rolling element bearing is going to be less likely to bind, but that's it. A spherical bearing allows significantly more angular misalignment than a standard bearing or bushing, but they transmit axial load and radial load. As such, I don't see how they could "absorb" side load. They would merely pass it on to the supporting components.

There are spherical bearings of many varieties, roller and plain. There are many types of self aligning bearings too, which don't necessarily have to be spherical bearings. If the way to reduce side loads on the shock is to provide a larger degree of angular freedom, then self aligning bearings are the solution. The same problem could also be solved by making the rear linkage stiffer. I am not a frame designer and do not know which would be better, but there are multiple ways to solve the problem of side loading shocks, and I suspect that spherical roller bearings are not the right option.

This isn't to say that using self aligning bearings in the appropriate places isn't a good thing, or using ball or roller bearings instead of plain bearings won't result in lower friction, because it will. However, I think it is important to be clear about which components we are talking about, what they do, and how changing them will improve the bike and the reason for and against the changes.
  • + 2
 All the 'problems' with fsr can be solved with an Ohlins coil and a bit of tuning. Completely changes the feel of the bike
  • + 2
 I have owned 1 of these bikes since release and up until this review I thought it was a pretty good bike ????
  • + 2
 It still is a good bike. Do you enjoy riding it? Does it make you happy? That matters more than whether or not it could be more progressive or a more efficient climber. But it is fun to take a closer look at the numbers and science behind the design.
  • + 2
 The thing that was clearest to me was: the flip chips are useless and only there because marketing.
  • + 1
 Shit man, we all learn from this article but imagine the author already knew all that shit! Incredible!
  • + 1
 What kind of engineering degree does it take to do this? I’m in school and this is very appealing to me.
  • + 1
 Any of them. Reading and interpreting some curve is everyday job for any engineer, and for many people that works in science or any technical fields.
  • + 2
 Mechanical engineering would be the most direct path, though civil engineering and others could probably get you there.
  • + 1
 @ReddyKilowatt: Or possibly structural engineering, in which case you would have a fall back of being involved in the building industry.
  • + 1
 I had a mechanical engineering degree with a motorsports bias. Then taking every opportunity possible to do something bikes, be it machining mech hangers or welding up frames. It all helps build experience that sets you apart.
  • + 1
 @ernestozed: That's usually just a specialization of civil engineering.
  • + 2
 and this bike looks damn good..............
  • + 1
 Bilstein should be coming along any moment now to unfuck the MTB shock selection.
  • - 2
 Weapon choice of CA bike paths!

140 travel, low bb... what's the point? Then you wonder why racers have to run 180 forks on this thing to raise the bb and make it work on rough terrain. But I wonder why they always have mechanical.
  • + 1
 Please write more articles like this!
  • + 1
 Sup SHONER
  • - 1
 For the average rider, that leverage ratio with a coil won't be an issue. Leverage ratio very similar to my mk1 patrol. Wouldn't run an air shock again.
  • + 1
 Impressive article. Thanks for writing this
  • + 1
 Nothing about wheel rate? This is actually what the rider feels
  • + 1
 Would love to see a pedal kickback plot..
  • + 1
 So exciting for my inner nerd!
  • + 0
 Please do one for the 18/19 Enduro. I want to know whats going on down there.
  • + 1
 It ain’t no Canfield...
  • + 2
 THANK YOU
  • + 1
 Please analyze the V3 Bronson!
  • - 2
 @dan-roberts is there an article that explains what the various terms mean? Great article but the terminology ( anti rise, anti squat etc) is confusing
Thanks
  • + 1
 www.google.com
  • + 1
 @nouseforaname: Not even...its literally the article after this one on the homepage.
  • + 0
 @faul: thanks I didn't read that one
  • + 0
 please just close your excel file and go ride your bike...
  • + 0
 Spesh are good at getting suspension tunes far from good on occasion.
  • + 1
 Ruff times for the EVO.
  • - 2
 Seems to me like most of the shortcomings of this bike were addressed by Transition in 2017 when they introduced the Sentinel.
  • + 0
 Flex when turning left, stiff when turning right is the sidearm.
  • + 0
 How nerds dis things
  • + 0
 Huh?
Below threshold threads are hidden

Post a Comment



Copyright © 2000 - 2019. Pinkbike.com. All rights reserved.
dv56 0.121253
Mobile Version of Website