Exploring the Relationship Between Handlebar vs Stem Length

Jan 10, 2019

It turns out that stems can be too short. Fabien Barel was on the ground floor of rider-forward geometry while he was riding for Mondraker back in 2012. I remember when he rolled out on a pre-production Foxy that had a massively long top tube, a steep-for-the-time seat tube angle and a crazy, 15mm-offset stem. I peppered Barel with questions about the stem while we rode together on his home trails near Les Gets, France.

When asked why Mondraker stopped at 15 instead of making a zero-offset stem, the former World Champion was candid: “We tried zero offset and the steering was too unstable. Fifteen is as far as we can go, and maybe twenty is better.”
Fabien Barel's 2012 Mondraker Foxy pushed the boundary for short stems - perhaps a little too far.

When is a Stem Too Short?

Today, stem lengths have crept back from 50 to 35 millimeters (20 if you add Pacenti’s P-dent stem and bar combination). I was reminded of Barel’s discovery after I switched handlebars and experienced a similar instability. The new handlebar had similar numbers, but I would later discover that, in conjunction with the bike's 35 millimeter stem, my hands were in line with the steering axis – a position, I assumed, that approached Mondraker’s zero-offset stem. Curiosity led me to measure a number of stem and handlebar combinations and to the discovery that the brand of handlebar you choose, and the angle that you set it can alter the effective length of your stem by over 50 percent.

Kirk Pacenti's PDent bar and stem combination offers stems as short as 15 and 20 millimeters.

Working with the theory that a mountain bike’s steering is somehow stabilized when the rider’s hands lay ahead of the steering axis, I chose a handlebar with a different bend that did just that, and the bike’s steering returned to normal. The difference in hand position was only ten millimeters.

Oddly, I raced motorcycles in various disciplines, and almost every handlebar put my grips at or behind the steering axis. No instability issues there. The difference seemed to be that you grip a moto with your legs, which isolates your body from steering inputs. While riding a mountain bike, however, your contact points are most often the handlebar and pedals. Most of the time, there is forward pressure on the grips, so it stands to reason that having the grips in front of the steering axis would cause the steering to self-center, which would become a stabilizing force. Fabien Barel is a smart guy.

Gemini's Kastor one piece carbon handlebar illustrates how the bar and stem operate as one simple lever. Gemini photo

What the Handlebar Has to Do With This

Before we get any further into this discussion, think of the stem and handlebar to be one welded structure, instead of two components. In reality, your hand position, relative to the fork’s steerer tube are the only components in the equation that matter. Imagine three points of a triangle, two at the middle of each grip and one at the center of the stem’s headset adjustment bolt. That’s a very obtuse triangle, and now that 50 millimeter stems are considered to be long, there are less than 30 millimeters of wiggle room for rotational adjustments and sweep-back angles before those three lines converge into Barel’s danger zone.

Geeking in the Basement Workshop

Just for fun, I amassed a number of handlebars for a test. I made a table/fixture that held a fork steerer tube at an imaginary 66-degree head tube angle. I mounted up a 45-millimeter stem and cobbled together some measuring devices to ensure that each bar was set at the same up-sweep angle of five degrees – the average angle that most bar makers (and riders) prefer. Some lock-on grips allowed me to measure each bar at a 780 millimeter effective width for consistency. I made reference marks at the center of each grip and the stem bolt, and then stretched a length of gear cable between them to ascertain the distance that the hands were positioned ahead of the steering axis (center of the stem's headset-adjustment bolt). Here’s what I discovered:

The "steerer tube" was set at a 66º angle.
The popular Renthal Fatbar measured 26mm.
The Syntace Vector 8 measured the longest, at 30mm...
...While the Syntace Vector 12 measured the shortest, at 7mm.

Rules: All handlebars were measured from the center of the grips (66mm inboard) with the outer ends of the grips at set at 780 millimeters wide. The upsweep for all bars was adjusted for the first part of this experiment at five degrees. The Race Face Atlas was recommended at 4 degrees. All others (where stated) were listed at five degrees. The Easton Havoc and Race Face Turbine 2 were chosen because they had 35mm clamp sections. A 40mm stem was used and their effective lengths have been noted in the chart. The manufacturer’s back-sweep is stated in the text. The numbers, rounded off to the nearest millimeter, are the distance forward from the center of the steering axis – that’s your effective stem length

Handlebar-Adjusted Stem Length

Handlebar

Syntace Vector Superlight 8
Syntace Vector Superlight 12
Race Face Atlas
Race Face Turbine 2
Renthal Fatbar
Gamut Cillos DH
Easton Havoc Aluminum
Back-Sweep

12º

Effective Stem Length

30mm
7mm
23mm
22mm*
26mm
24mm
21mm*
*Denotes 40mm stem, which reduces effective length by 5mm

Oversize, 35mm clamp sections like this Easton Havoc's have pushed the sweep-back bends outwards.

The takeaway here is that handlebars with similar back and up-sweep numbers often do not position the rider in the same place. Where the bends occur in the span of the handlebar create different effective stem lengths. The differences are not huge, but they can be significant. If Fabian Barell’s observations are correct, and I believe they are, a handlebar-adjusted stem length around 20 millimeters would be as short as you’d want.

These numbers were derived using a 45-millimeter stem. So if you are running a 50, you’d need to add 5 millimeters to the effective stem lengths of each handlebar and conversely, subtract 10 millimeters if you were using a 35-millimeter stem. Using a stem that short would make it easy to arrive at a bar/stem combination that would put your grips behind the steering axis, and that's probably not good.

Using the “string” measurement technique that I demonstrate here can help you determine whether your handlebar and stem combination is in the ballpark, or if that combination warrants experimenting with a different length stem. You might be surprised to discover that your 50-millimeter stem is tinier than you believed it to be.

Stem-length Adjusted for Handlebar Angle

How much you rotate your handlebar to suit your hand position affects the calculated length of your stem to a much greater degree than the particular bend configuration of your bar. Twenty-millimeter rise bars are popular these days, so I used the Race Face Turbine 2 to demonstrate. I rotated the bar to produce seven, five, and three degrees of up-sweep. Here's how it came out:
Handlebar: Race Face Turbine 2
8º back, 20mm rise, 5º up

Rotated to 7º up = 36mm
Rotated to 5º up = 22mm
Rotated to 3º up = 15mm

You can see that when you rotate your bar to achieve your sweet spot it can dramatically change the effective length of your stem. That change would be greater with a higher bar like the 30mm-rise Renthal or Gamut.

So, What Does All This Mean?

First and foremost, if you always run the same brand, model and width of handlebar, and are careful with your setup, then switching to a different length stem should provide instant and clear feedback. You’ll either like it, or you won’t, and you'll know the cause.

What this experiment suggests, is that the trend towards shorter stems has narrowed the range of rotational adjustment and hand positions, and that makes it easier to fall outside of stable parameters
and end up with undesirable steering qualities. Also, the particular bend of each handlebar maker’s design should be considered as a factor before you settle on a stem length. Shorter may not be better in some cases, and slightly longer might be a stabilizing factor.

Here is a simple tool that you can use to assess your starting point and, should you choose a different model of handlebar, or entertain a change in stem length or rotation, you can assess the ramifications in a minute or two with a piece of string and a ruler. If your set-up is golden, you’ll be able to reproduce it with any number of bar and stem combinations. If it's not, you can determine why and make positive adjustments towards a solution.

Author Info:

Member since Mar 23, 2011
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262 Comments
• 159 23
Buy the two you like the look of, then adjust so it feels about right, then tighten the f*ck out of all the bolts so you don’t end up on your face. Then...

And only then, go ride it.
• 21 77
I couldnt scroll past the geeky parts fast enough.
• 183 23
If you "tighten the f*ck out of all the bolts" you are more likely to end up on your face. Just sayin'. There is a german saying: after tight comes off.
• 323 25
@jzPV: It was a joke. You know, joke, the word that doesn't exist in German
• 47 95
jzPV (Jan 10, 2019 at 8:44) (Below Threshold)
@pakleni: I don't usually joke about people over tightening critical stuff and a landing on their face, and I know plenty of cases of just that.
• 99 19
@jzPV: bet you're fun at party`s...
• 66 3
@jzPV: you're so tight
• 20 3
Thank you for saying what most are probably thinking. Just tighten to spec. For the love of GOD... why must we over think so much.
• 73 0
wait, so am I supposed to tighten or f*ck the bolts?
• 6 0
@robt78: probably tighten, as the latter would probably wind up with you losing your bolts lol
• 3 13
@jzPV: That's because your German.. Hense what @pakleni said.
• 2 2
This is the best comment. End of. Next.
• 79 0
@jzPV: I always thought the german saying for torque spec was: gudentite
• 18 0
@jzPV: Okay, tighten until it spins and then back it off a quarter turn.
• 9 0
@Kiotae: usually we tighten bolts 'handwarm'.
• 11 0
Part of the reason it’s that easy for you is because a bunch of geeks have overthought it for a few decades...
• 9 13
@DrPete: Yeah same sort of overthought mentality has created dropper stem and vajankle so take it easy
• 12 1
Instructions unclear on tightening and f*cks. Appendage caught in stem
• 3 1
@robt78:I'm pretty sure that's what @jzPV is advocating......
• 7 2
@WAKIdesigns: innovation comes when you have a bunch of people out there trying crazy stuff. 99% of it doesn’t pan out, but those crazy ideas are needed.
• 4 11
And what makes you think this one makes sense? @DrPete:
• 1 5
fat-hub (Jan 10, 2019 at 20:35) (Below Threshold)
@jzPV: Is that with cheap German Aluminum?
• 1 1
@robt78: If you're unsure, screw them.
• 32 2
Yeah, Germans don´t know jokes. That is not correct. I just looked the word up in the dictonary, interesting stuff!
• 6 8
@robt78: instructions unclear dick stuck in stem...
• 1 7
lehott (Jan 10, 2019 at 22:53) (Below Threshold)
Well iv got Carbon stem & handlebar......I wouldn't wanna be 'tightening the f*ck out of all bolts'. A Park Tool Torque wrench does the job
• 12 0
Tighten it till it strips, then a quarter turn back
• 2 1
@Rig: lols!
• 6 0
@pakleni: because Swiss are known for their remarkable humor.....
• 10 6
@thedirtyburritto: If I was to generalize based on Pinkbike interactions, the biggest number of stiff folks come from UK whereas Americans get easily offended. Germans are within all norms
• 1 0
you forgot 'and then tighten just a little more'
• 2 1
@thedirtyburritto: Swiss maybe not, but when it comes to people with balkan blood, nothing comes close to their humor. Isn't that right, @pakleni
• 3 3
@lg13: Scotts... the best mix of being rough as baggers ass and sharp when joking. Being from a Slavic country I can say that humor disappears rather quickly with increase on bank account or worse with religiousness. Skin gets thinner and we get easily offended. Also make sure you don’t mention the War... My favorite is Spanish and Italians when you press their football buttons... Real Madrid is the best team in Spain right? Puta!! I envy them though, the ability to joke with girls about shagging. Anywhere anytime. And they (girs) are entertained. Somehow others don’t get a pass... and you know how these days it can get you in trouble.
• 1 0
@jzPV: How would that translate? I used the google and got "nach eng kommt ab" or "nach fest kommt ab" Which one is accurate?
• 2 0
@redrider3141: the latter is correct.
• 2 0
@hairy1976: parties
• 1 0
@jzPV: I have never encountered this before but I'm hearing it in my head with a German accent and I am SO happy
• 40 2
If you think all this stem/handlebar info is garbage marketing stuff, then I'm happy for you that you haven't reached the stage in life where your body starts to break down. Once that happens, you really have to pay attention to the ergonomics of your bike.
• 7 1
16 degree back sweep? I am considering getting a pair to see if they sort my carpel tunnel numbness.
• 5 1
@fartymarty: I switched to 11 degree back and super happy with the increased comfort - no more numb hands on long rides. Definitely going to try the SQLab 16 degree when I save up some cash for it :?
• 1 0
Absolutely. I have a bad back so just switching from a flat bar to one with 15mm rise relieved my back pain. It was for my DH bike so they'll stems was already at the top of the stanchions.
• 4 0
Those SQLab 16s were great on my last bike, but when I switched bikes I had to go to a SQLab 12 back. The 16s were just too much. SQLab states that the 16 is better for more laid-out positions and 12 is better for upright. Keep in mind that width affects the best sweep for you as well. It can take a lot of trial and error to get a perfect setup to avoid numbness or other issues. As a side note, the SQLab 30x bars go forward some and then sweep back so the effective stem length is not affected as much.
• 3 0
@thinkbike: definietly helped my wrists
• 72 0
More important are the ergonomics of the chairs we sit on while on Pinkbike 4 hours each day.
• 8 0
Yeah I'm a big fan of my Syntace 12 degree sweep bar, everything else seems too straight for my wrists. Based on RC's measurements that would explain why I'm still using a 65mm stem with them as well, it actually puts me in the same place as a more traditional 50mm stem with straighter bars.
• 1 2
@fartymarty: I've had the surgery to correct my carpel tunnel issues, it was worth the recovery time to be able to ride in comfort. I tried all sorts of grips, gloves, setup positions and the like but in the end the surgery was what helped me the most.
• 2 0
@DJ-24: What you don't sit on your bike and make noises while surfing PB.
(bike noises that is)
• 1 0
Atom lab dh bars are pretty sweepy also
• 2 0
Thumb joint pain/swelling is my reality now that I have hit my early 40's and I am looking at this much closer at this. I got C's in my college physics classes but doesn't a longer stem coupled with a greater backsweep bar change the leverage rate over moving the bars- even if the relative grip position stays the same?
• 1 0
@slabba53: have you tried softer grips in different sizes? Thicker grips relieve hand pain for me
• 1 1
@DJ-24: By chairs, you mean toilets?
• 2 0
@ThunderChunk: I have the ESI chunky grips on both my bikes but most of my hand pressure is towards the thumb- need to shift that towards the heel of my hand. I really don't want to use those weird looking Ergon grips- might as well throw on some bar ends and a mirror if it comes to that.
• 2 0
@Explodo: I now have them on both bikes and really like them. Now I just need to sort the roll.
• 1 0
@slabba53: Definitely give Ergon GA3 grips a try. Made a difference for my thumbs.
• 1 0
@thinkbike: Resurrected. I get numb hands also, but it seems to be from pressure on the outside (pinky) of my palms. Seems to me like more sweep would create more pressure on farthest end of bars? Am I missing something? Or where do you feel pressure on your hands?
• 36 1
• 8 0
Thanks for the share
• 3 0
Love this - have shared with all my bike nerd friends.
• 2 0
Good stuff! Will stretch my head thinking about this next time I ride.
• 4 2
Still a pop article though. If you wanna bike nerd hard you gotta go to the ref list where the real work is happening. Let me know if anyone is truly interested.
• 1 0
@sspiff: interested. Anything in particular in the references as a good jumping in point?
• 7 1
Surprised to see there is no link in the homepage towards Lee's related article:

www.pinkbike.com/u/leelikesbikes/blog/dialing-in-your-steeringhands-offset.html

I'd rather just skip RCs article if I know there is an expert article available already. It is a lot of information already, no need for extra noise.
• 2 1
@vinay: Yeah, me too. Seems to be relevant and thoughtful. How'd you find it?
• 1 0
click error
• 1 0
@vinay: Thank you for enlightening us (with www.pinkbike.com/u/leelikesbikes/blog/dialing-in-your-steeringhands-offset.html ) past this "Exploring..." article here, which I find rather judgemental in indicating that one thing is right and the other is wrong.
• 1 0
@vinay: Thanks for that. I'm currently running a SHO of about +5mm and will probably take it back to zero to see how it is. Why is this not more widely mentioned as I see it as one of the fundermentals of how a bike handles. You can have the best performing suspension / components in the world but if counts for nothing if the set up is wrong.
• 33 11
I like my cockpit a certain way. I adjust all my bikes the same way without the use of measurement tools. I'm at the point where I can sit on a new bike, eye it, and adjust as needed to fit my preferences. I have yet to come across a bar/stem combo that couldn't fit my preferences.

Who's to say that person A likes quicker, more unstable steering and person B, C, and D likes the opposite. 'Bike fit' is completely based on the rider. No 'bike fitter' is going to tell me I should make adjustments because according to his/her calculations, it's the 'perfect' position for someone of my height and weight. Bike fitting is nonsense. The rider should be the one doing his/her own bike fit.
• 46 0
I got laughed at by a chiropractor for not getting my bike professionally fitted. He also showed my ex-wife that he'd beaten me on a strava segment. Lol.
• 55 0
@skelldify: Your chiropractor seems like the type of person that would get a bike fit.
• 23 0
@Almazing: Whoa, whoa, he's not MY chiropractor, just A chiropractor. My ex-wife's in fact.
• 25 0
@skelldify: My apologies. In any case, he seems like a douche.
• 18 3
@skelldify: Sounds like he hangs with dentists
• 4 1
yes, but it is important to consider the tradeoffs between different setup options. A comfortable position of the bar and stem will also depend on the overall bike geometry. If we take different bikes and just modify the stem length and position to create the same height and distance from the grips to the BB, they will feel very similar in the parking lot, but very different while steering through a fast and loose surface. Whether we are faster or slower, we have a certain response speed, and improper leverage on the steering will prevent our control loop to apply the proper response. A very short stem is like driving a fast car with very sharp response to a small steering wheel. This article also shows that once we have the optimal stem length figured out, the preferred tilt of the bars might require us rethink the right stem length.
• 2 0
@theboaz: I agree that there has to be a foundation to build upon one's preferences. For instance, I like my bar rolled a little more forward than my friends' bars. After switching to their bikes, I find that the way their bars are set up is pretty foreign to me. It wasn't deal breaking as I could still ride their bikes pretty hard, but I was never completely comfortable with it. And they same for them. They mention that my bar is rolled a little more forward than they would like and it felt weird. I feel that many mountain bikers serious about the sport have their own preferences not only with bars, but with geo in general.

Bike geometry itself are tradeoffs between two extreme ends of the pendulum. At the end of the day, the rider needs to figure out which is important to him/her adjust their bike accordingly. No amount of measuring tape, protractors, and yard sticks is going to tell me that.
• 15 1
"Bike fitting is nonsense."
Hear, Hear! Especially for mountain bikes.

How steep are your climbs? How steep are your descents? How much time do you spend on the flats? Do you want to trade climbing performance for descending performance? Do you climb out of the saddle or seated? Is your brake lever on your fingertip or is it at your 2nd joint? Do you like your wrists straight or rolled back a bit? Etc, etc.
• 23 0
@skelldify: he sounds like a douche

what else is this Chiropractor showing your ex-wife?
• 15 13
@skelldify: i feel like every American has a chiropractor or a therapist*, or both. Is that correct?

*except for your president maybe
• 17 0
@Muckal: i have neither, but my dog has a therapist and a full time masseuse
• 9 7
@Muckal: Personally, as an American, I will start listening to chiropractors the day they become real doctors.
• 13 4
@ZappBrannigan: Real Doctors will be happy to give you pills or a referral to a surgeon, Good Chiros have their place. Stuff that is misaligned and needs to be put back, If I can do it without being cut open I am all for it.
A( Real Family Docto)r usually knows shit about the human anatomy they are programmed to push pills.
Also Famly GP's usually know shit about drugs so best ask your Pharmacist about the drugs your GP has specified.
• 5 1
@ZappBrannigan: it's called a DO dude. Go to a solid DO instead of your MD. Same thing 90% with the same doctorate governance and residency but with a more holistic focus.
• 4 1
@ZappBrannigan: I use to be skeptical of chiros until I was convinced to try one and was suprised that it really works. I've tried a few over the past 12 years (I dont need to go often) and there is a big difference from the good ones and shitty ones.
• 6 1
@Ride406orDie: good chiros do their thing well, and the key is finding the ones who know their scope of practice and know when to call an MD/DO. If you go to one that claims s/he’s going to cure your lung problems or cancer or something, RUN away.
• 1 0
Dude... you're right it's all about personal preference... the Carrington effect u know.
• 3 1
@SJP: I had my mtn bike fit. I had cleat position, saddle height and fore aft set. It made a big difference on my knees. I would get knee pain before and no more knee pain after. I had it done after getting road bike fit for the same knee pain issue. 10-20 miles and my knees were done, they made a few pretty minor adjustments and boom no more knee pain.
• 1 0
So I thought the same thing until I got these sq labs high rise bars with an insane 12 degree back sweep paired with a 35mm stem. Big mistake I'm finding out with this article confirming. I eyed the initial setup set similar to previous builds and feel. I had several bad twitchy unstable rides. come to find out I was behind the steer axis due to this poor combination. So I had to get a longer 50mm stem to keep it right. But overall the backsweep is still too intense..
• 19 1
From an interview with Sam Whittingham of Naked Bikes. www.handbuiltbicyclenews.com/c23-bicycles/328-nakeds-framebuilder-notes-on-a-prototype

"Steering Axis
Needs to be as direct as possible. For most mountain bikes this means super short stems. It is not so much the short stem that is important but the resulting hand placement relative to the steering axis. A stem with a 32mm reach on a 780mm bar with normal sweep gets you pretty close to being in line with the steering axis of the front fork. being in front of the steering axis in the old days especially with shorter bars and long stems is what gave us the feeling of wheel flop and the horrible jack-knife scenarios."

"Wide bars
I think we have already pushed this one too far. I just don't see the mechanical advantage of going past 800 for most people or even 780. I go a bit less than this, but only because my local trails are a bit too tight for super wide."

"Lower bars
The long front-centre gives you so much more stability and less chance of pitching over the bars, you no longer need to have a high hand position. I can see a real return to wide flat bars, with "riser" bar looking dated real fast. Slacker head angles helps lower the bars. It will be interesting to see what people do to keep bars low enough as the forks get longer and longer.
Frame design and straight down tubes. I'm so excited from a structural point of view to be returning to straight downtubes. With a long front-centre and slacker head angle, I no longer need to use kinked downtubes for fork crown clearance. This is so much stronger."
• 7 0
I've experimented quite a lot with bar height, effective stem length (which is a phrase I first used back in 2014 according to google!), head angle, front centre and so on. I've found that longer reach fits better when paired with taller stack height. I've found that I don't like how zero ESL feels, even 20mm adds a valuable amount of stabilisation when I hit a bump and there's a forwards weight shift. Conversely I don't like how a long ESL feels, as it turns the bars from a steering wheel to a tiller, which is just weird. Slack head angles work in most scenarios and shorter offset feels good on big wheels and long reaches.
• 3 0
Nice article, thanks for sharing!

I don't say the author is wrong on all points but I have at least a different opinion about 29+ tires: the rollover ability is definitely here but I found them really heavy to accelerate and never found a pressure where I was neither hitting my rim way to often or bouncing around...

Nice to read many people expressing their views about bike geometry and bike fit. There has been quite a few recently.
• 15 1
All the "effective stem length" numbers are wrong. Based on the measuring system used, this is giving delta's in reach on the X axis but the stem is at 25degrees from the X axis. So the numbers given are NOT effective stem lengths.
(effective stem length)=(listed effective stem length)*(sin(head angle)).
• 2 0
It would make sense to call it cockpit reach. And it would only apply to the whole system, head angle - stem - bars. Handlebar manufacturers should include (negative) reach in their data sheets in the neutral position (roll-wise) anyway.
• 1 0
@martn: Yes! I've been saying this for years. Giving us two bend angles is meaningless when every rider clamps the handlebars with the grip area in a horizontal or slightly inclined plane. I want 4 standardized measurements for bar fit: width (mm), bend (deg), stack (aka rise)(mm), and negative reach (mm). All measured with the grips rotated into a standardized plane (horizontal, or maybe 5° inclined).
• 2 0
@bcmanucd: As a good starting point SQlab introduced a neat way for the user to easily find the neutral roll, so the angles match the data sheet. They slit the right end of the bars just a few millimeters so you can put in a business card or something similar and eye it up parallel to the ground. Much easier than trying to align some laser etchings next to the stem or trying to get the rise in a vertical plane.

Unfortunately they don't specify negative reach either and I don't know how everyone seems to measure rise differently. The 12° 3OX I got for a new bike turned out to have significantly more negative reach than the 12° Syntace Vector on my other bike. Both measure 780 mm wide. It's also virtually impossible to tell a difference between the SQlab's 30 mm rise and the Syntace's 20 mm (which might come down to a difference in upsweep). Anyway, it shouldn't be that much of a guessing game.
• 10 0
It seems somewhat self evident that more backsweep will reduce effective stem length but it's interesting to see that quantified. Another thing I'd like to see quantified is bar stiffness i.e. a universal way to compare different bars' degree of flex and pliability. They're definitely not all the same but you have to refer to random qualitative judgments from people of all levels of strength, weight and skill to figure it out.
• 8 0
Really great to see some hard data. One thing you didn’t address was the change in reach as bar width changes. Ihave calculated it out and very roughly, every 25mm in bar width change results in 10mm of reach change, all else being equal. Again, this is rough, but gives a starting point when changing bars. Going from those old 710 bars with an 80 mm stem to 780 bars, a 50mm stem will keep the reach close. This of course is dependent on the bar sweep being consistent, and as your testing shows, the sweep being at the same point in the bars.
• 10 2
A rather inciteful little article. I appreciate the nerdy stuff that can be applied to help achieve a more stable and overall better ride. Stuff I normally wouldn't think about but will be extremely useful in setting up future bikes. Going to be measuring to see where my bike sits as soon as I get home now. Thanks Richard.
• 23 1
To Incite and to provide Insight are two different concepts just saying.
• 12 1
@endlessblockades: tho as the comments sho... both are appropos here
• 1 0
@WoodenCrow: Very true! That's probably the goal of most of these explorations: Eyeballs and Clicks.
• 3 0
@endlessblockades: Hahaha! I meant "insightful." I shouldn't be allowed to write comments before noon. ;-)
• 7 0
@endlessblockades: I think he used the correct word, because I'm angry as f*ck now.
• 12 1
Paging PVD. Come in, PVD.
• 8 8
The above article is completely wrong. This guy doesn't seem to understand the subject.
• 5 1
@bicycle019: why, PVD, would that wild reverse-bar stem contraption go around a corner faster than my 27.5" slash with high set lowrise 750mm bar on a 40mm stem, even with my suspension locked out. I'm skeptical.
I'm probably all that's wrong in the world to you eh?
• 6 11
pvd666 (Jan 10, 2019 at 19:26) (Below Threshold)
One of us has a body of work that theorizes, builds, and tests concepts. The other doesn't. The choice between the two seems rather obvious.
• 4 0
@pvd666: dunno why you posted that, I didn't claim to be a bike expert. I actually asked you why your concept bike would go round a corner faster than my archetypal enduro bike with bar grips 10-15mm forward of steering axis, "you people don't understand what you're talking about" is your informed response? on yer bike mate
• 3 3
@Vastusaurus:

I read the comment differently.

My bikes use forward geometry concepts as I've written extensively about. Take a look at the blog. There's a lot there to help you figure out your own bike geometry.
• 1 0
I think, that PVD design uses flat bar. Stem is mounted higher and hands are farther from head axis due to backsweep. Rider creates momentum on stem and force vector non parallel to axle that centers wheel. Difference is that PVD has this force forward and "classic" design has this force backward to bike axis.
So actually very short stem and bar backsweep setup can cause instability due to force applied directly on head axis.
Please @pvd666 confirm if I'm right.
• 1 0
@Eneen:

You're off. The fore/aft position of the hand grips relative the the head axis is completely irrelevant to the handling. The article is completely wrong in it's premise. In design, we really don't care about the stem, or axis, or bars...as long as we can place the hand grips where we need them.
• 1 0
This starts to be interesting, thank you @pvd666, have to re-think this.
• 1 0
@pvd666: Surely this is contradictory to www.pinkbike.com/u/leelikesbikes/blog/dialing-in-your-steeringhands-offset.html. If this is the case then a 150mm stem will feel the same as a 30mm stem.
• 1 0
@fartymarty: LLB should be totally ignored. He isn't a geometry guy.
The steering axis isn't a consideration for placement of grips.
• 1 0
@pvd666: How do you define grip position? Is it to do with fit or relationship to contact patch?

What I really want to know is how I position my bars / stem etc.
• 1 0
@fartymarty: the best reference is the end of the grip to the crank axis. You should develop a setup print of your bike to define all of the driving parameters.
• 1 0
@pvd666: sounds like I need to draw my bike out in CAD.
• 2 0
@fartymarty: It is impossible to have a discussion about fit and geometry without that. BikeCAD makes it easy but isn't super friendly with fs bikes. Still, very useful.

www.peterverdone.com/bikecad-pro-17-5-and-bikecad-free-17-5

You can see how I approach that on my wife's recent bike.

www.peterverdone.com/bikecad-pro-17-5-and-bikecad-free-17-5
www.peterverdone.com/suckered-by-junk
• 8 1
Good article. Stem length is just a catch all for body position. Only reason they are shorter now is because of longer reach and wider bars. You only have so much torso and arms that won't ever change.
• 5 0
Short stems and wide bars are the result of riders looking improved handling and control. Longer reach is a result of this. If seated fit was the only thing that mattered, I would still be riding with a 135mm instead of a 35mm stem.
• 3 0
Well said. This whole longer reach and wheelbase marketing thing has over looked body position as the first platform of stability. An upright body position can act and react faster than one leaning forward reaching to hang on the bars. What is better for uphill isn't what is best for going down. That being said... different people, different styles.
• 2 0
@Legbacon: agree on wider bars for control, but longer reach is not a result of wider bars. You would want to shorten the reach with wider bars. I think longer reach is the result of longer wheelbase with shorter chainstays increasing the distance between the seat and handlebars. This is why seats are getting steeper now designers are trying to position the rider forward again. Feel like bikes in the last 5 years have totally ignored F/R rider balance.
• 8 1
@RichardCunningham - good article. Is there any relationship between effective stem length and fork offset that effects steering?
• 2 0
one of the DH pros mentioned that in article this fall. said he preferred them roughly equal (idk if that was actual or effective stem length he meant close to equal with fork offset).
• 2 2
No. There is no relation between the two. Fork offset only affect the trail value, and trail value alone doesn't tell anything.
• 4 0
@WoodenCrow: "one of the DH pros" was none other than Mr. Greg Minnaar
• 1 0
@WoodenCrow: If I understand the article @bwcyyc posted above (www.nature.com/news/the-bicycle-problem-that-nearly-broke-mathematics-1.20281) -side not: I definitely don't understand it- then steering stability can be achieved with more forward weight. So it would stand to reason that as stem length increases, fork offset could increase, and trail therefore decrease, and steering stability would be maintained. Obviously that can only go so far, since I think a lot of what we feel as "stability" is having enough of the front wheel in front of us to avoid being worried about OTB's
• 3 0
@faul: Sooo many people would disagree with that statement. On 2D drawing it maybe doesn´t matter, but ir real world it absolutely does and you don´t even have to be engineer to see why.
• 1 0
@kjjohnson: Thanks! I had a feeling it was the Goat... but din't want to put words in his mouth, of all mouths!
• 1 1
@WoodenCrow: I read somewhere that Greg Minnaar liked to have a stem shorter than his fork rake.
• 1 0
Perhaps in the above replies, my memory isn’t so good.
• 1 0
@Mondbiker: Why would they disagree?
Is there a relation between the two?
Fork offset does something else than modifying trail value?
You can say something about the bike only looking at trail value?
• 2 0
@faul: the question was if offset and stem relation affect steering, the answer is yes, they both affect steering and therefore relation between the two also does affect steering. shorter stem makes steering faster, just like shorter offset does, shorter stem with shorter offset on bike with steep head angle would most likely make steering even too fast(or too responsive) if we didn´t have so wide bars these days (they slow steering down obviously), but positive thing about short offset is that it reduces wheel tendency to tuck under in tight corners that require more steering input, so steering feels calmer yet more responsive at the same time, which is nice I guess lol. So to put is simply, everything between your hands and tire contact patch does effect steering in some way and there is balance to be found for the optimal result.
• 2 0
@Mondbiker: you're mostly correct, except that shorter fork offset increases trail which slows the steering (using your terms). The key point you're making is true and overlooked, including in this article: all these things matter, and yet also work to do different things at different speeds because bikes lean, and leaning means forces/moments change because the free body diagram changes, and wheel/tire (and even bar/stem/steering component) rotational inertia and dynamics come into play. Those equations are not easy to understand and slap on a Pinkbike article. It's helpful to look at one simple combination of bar and stem specs to help people understand that they can't ignore their interplay, but to ignore the rest of the geometry to make a statement about what effective stem offset is "good" or at the limit of stability is misleading and oversimplifying it greatly.
• 1 0
Absolutely. All those things, in conjunction with head tube angle at whatever F/R suspension ride heights you're at during any given moment,and wheelbase, and wheel size, and c.g. height, and steering and lean angles, and speed, and probably a few other things I'm not thinking of at the moment, all affect the way a bike "feels in a turn". But...the basic combination of handlebar dimensions and stem offset are certainly overlooked. Hand position relative to the steering axis is the dimension he's defining. Wheel contact patch vs the steering axis is the other end of the equation. That dimension comes from fork offset, wheel size, and the dynamically changing things I mentioned like head tube angle (which changes with suspension travel differences between front and rear). Comparing the forces at the handlebar vs the reaction at the ground can then be done for any instant in time, while also considering dynamics like rotational inertia. And that shit is complicated and most people don't know how to or want to deal with that. So we look at individual or a combination of static measurements and try to understand how they affect how a bike feels :-)
• 2 0
@Mondbiker: I didn't undertood the question the same way.
Obviously offset and "stem" both affect steering. But there is no relation between the two that gives an idea of how the bike will react.
effective stem lengh gives a stable position (the center of the bar being the furthest away from COG). Increasing the effective stem lengh will increase potential energy (at a given position of COG), increasing in turn the (really tiny) "stiffness" of the steering from this position.
Trail value in relation to wheelbase and wheel radius, will give another stable position of the steering, depending of the lean angle. It creates a relationship between lean angle and cornering raduis. that's what keeps you upright and it allow you to keep your COG more or less between your two wheels when cornering.
Because of these two points, you only have to lean your bike (fitting the stable cornering radius and the corner you are riding) and more or less push on the bar (aligning your COG with the front wheel, outer pedal down and elbow out helps) to corner, rotating the bar is only required for minor corrections. There goes bar width but it's another chapter.
So, as there is two different things happening, effective stem lengh and offset (in trail value) being separately involved, in no way you can find a relation between the two.
• 2 0
@faul: Interesting additional commentary. I was confused by your first comment also. I think we're all saying the same things: there are a ton of variables in the bike handling equation, and they all matter. I think it's helpful for people to understand what component changes can do to steering feel (or anything else) in general, but I struggle to see articles like this that draw somewhat "absolute" statements about one geometry variable when there are so many things that go into how one bike feels that comparing a single dimension (or effective dimension) between multiple bikes will not give you ability to draw firm conclusions.
• 1 0
@dirt-klaud: @Mondbiker: @faul: thank you all for diving into this a bit. Like life, every aspect is interrelated and perpetually affecting and being affected by feedback loops of various magnitudes. Though it may appear to oversimplify the complex whole, the value of RC's research here is its pragmatism -- bar and stem are relatively cheap and easy to swap, unlike fork offset, head tube angle, BB height, and the rest. Thanks for the getting down the with tools and giving us some real numbers! @RichardCunningham
• 1 0
@dirt-klaud: Yeah I think this is the rare case of not arguing but not slight misinterpretation going on, well said, I believe we all agree that it´s very complicated with so many variables affecting steering to say what works better, if you only had one head angle and one offset, it would be little bit easier, maybe @faul few well made point man. Good debate guys!
• 11 2
Choose the bar and stem you like and be a d*ck about em!
• 9 1
Meanwhile, I am working at a desk and long to ride my bike....
• 3 0
Back to work.
• 7 4
Richard should have given credit or at least mentioned Lee McCormack who went through all this stuff in his newest book which he also presented in some previous post (whether or not you like his acronym-laden style).

Lees conclusions however where that for his light hands heavy feet style hand position at steering axis provided the most neutral and flexible setup since you are neither stable nor unstable.
• 16 3
Lol, he also said that you could calculate the handlebar width you need from your height. I'd say that discredits anything he says about bike fit.
• 3 3
Other than the problem that Lee's system is all BS without they key (noted in the comment section) requirement for an angle.
He is right about handlebar setback though.
• 1 1
Thank you! @skelldify:
• 7 0
@skelldify: Some people my height have 5 inches less wingspan/ape index.
• 1 0
Agree@gnarnaimo:
• 5 0
@ratedgg13: I made another post that addresses the angle of your RAD. Hopefully it's in the pipeline to be published.
• 1 1
@leelikesbikes: cool, looking forward to it. Tbh tho dude...it really needs to be a video. That last article was confusing for a lot of people. Video (I know, I know if we all paid it wouldn't be confusing but still it's good marketing regardless)
• 3 0
So what about the guys who use the handlebar backsweep to their shoulders (me) and others use the backsweep to the saddle (flat, i hate that!!)... Angled to the shoulders would make nearly 1cm the stem longer...
• 2 0
I was thinking about that too. How was the forward/back roll of the bars decided? Bars tend to have a variety of shapes. I tend to roll my bard forward a bit and have always liked how that felt regardless of brand. Based on this article that would increase the effective stem length.
• 5 0
That's exactly what RC used actual numbers to describe -- rotating bar between 7, 5, and 3 degrees changed efffective length from 36mm to 15mm.
• 1 0
@WoodenCrow: OK. Got it. My reading comprehension was obviously not good on this one
• 2 0
@LexB: sorry din't mean to come across like a douche - just typing fast, wanting the OP to see the author took it into account and made some helpful measurements
• 2 0
My preference changes depending on bike. Going from 27.5 to 29'er Trek Slash was quite different and I ended up with a different setup on the 9'er... mostly lower, lower rise bar + less spacers under the stem but also 10mm shorter stem.
• 3 1
So many things at play here. Lol. Relation seat height / stem height. Long leg / short torso vs short leg / long torso (my case) will have different input on your steering from the same frame size used by 2 different body type.

We can go on and on.

As an example, nothing to fault bike frame manufacturer because they use average Joe body type for which frame you should get.

I am 5’5” on a Medium Rocky Mountain Altitude with 35/770 stem/bar combo. Feels awesome! I tried the Small Altitude with 45/780 combo. Felt very unstable and frighteningly dangerous. FYI, at my height, RMB puts me between an XS/SM Altitude.

Again, experimentation. Remember 3 things if you are an intermediate to advance rider...

Feels:
1. It sucks / scary
2. It’s OK
3. Great / Awesome!

Experienced friends or coaches can help with determining this feeling.
• 1 1
20mm forward with a 32mm long stem and RaceFace SIXC 770mm wide (with grips on) on a 65 degrees head angle.

My seat is pretty much level with my stem at pedaling height. 125mm dropper if you care.

Pedaling Innovation Catalyst pedals.

Food for thought...
• 5 0
From here on in this measurement technique shall be refered to as string theory.
• 2 0
l was not going to comment but...

Of course all bike measurements are important.
Now what I don't see is how our body shapes are rarely taken in consideration.
Take two guys with the same height but one has long limbs and short torso and the other one has short limbs and long torso, and you have two completely different set ups.
Same thing goes with how your feet are shaped and turned, and also how your hands and writs are shaped.
Depending on the shape of the handlebar you may be putting pressure on the outside (hypothener) or on the inside (thener) of your palm and therefor inducing pain.

As for stem length and handlebar width it's all about feel
• 1 0
Hi there. I'm looking at a new bike and I'm all legs and arms with a short torso. 5'9". Do you think it's more advantageous for me to error on the side of a medium or a large?
• 3 0
I'm gonna be unpopular:
COSINE ERROR!
Not that it matters since all of the measurements are taken at the same "headtube angle", but what matters in theory is the distance to the axis of rotation, not the horizontal distance.
• 2 0
Great article RC. Thanks for introducing the concept of effective stem length.

One more thing to note is that, at a given backsweep, a higher rise bar will increase the ESL, because the extra rise is in the vertical plane and the steering axis is tilted back (the head angle). Getting the same rise by adding spacers will preserve the ESL, while increasing bar rise will increase it. So if you run a 40mm rise Renthal bar, you're increasing your ESL dramatically.
• 2 0
“Curiosity led me to measure a number of stem and handlebar combinations and to the discovery that the brand of handlebar you choose, and the angle that you set it can alter the effective length of your stem by over 50 percent.”

Ugh I’m that hater today... but you really only discovered this concept now?...
• 15 14
Hate to be that guy (honestly) but I am sad to see this reinsurgence of bike fit for mountain biking. Even though I respect a coach who does it a lot... there is no way around spending money on 2-3 combos of stems and bars, different lengths, sweeps, rises, then testing them for at least 1-3 months in each configuration.
• 37 0
Admit it, you love to be that guy!
• 13 19
@carym: alla this measuring, mental masturbation, yet 99.999999% of people run 40 stem and 750 bars and +/-10mm... give me a bloody break. Waiting for a company to release stems in intermediate lengths. 37.5/40/42.5/45/47.5/50 Richard Cunningham, Christ Porter and Leo Kokkonen will be the first ones preach it for their Joey nation.
• 6 2
Bike fit is still important on an MTB, it's just that we need to look at different measurements than road bikes. I for one am glad to see more emphasis on the right things lately (reach, spread, etc.) that focus more on the length of the bike vs. height like road bikes do. I agree that people that focus on old-school factors (like seat tube length) derived from road biking have it wrong. That's not what this article is doing.
• 9 14
@gtill9000: it is bullsht considering how bikes come in different geometries, how suspension setup affects how geometries changes all the time - Sorry. The times of 100mm stems and 680mm bars on 150 bikes are long over. As I wrote above - almost everyone runs 40mm stem and 750 bars. If you can't switch from a DH bike to a DJ bike, with big difference in geo, you are simply a crap rider and no math will help you. The real world experience and practice will help you. A long chain of failures. If you have issues coming from injuries, some nerve pains, it is personal and no article can help you. You have to go out, buy stuff, test it, you will possibly fail once or twice. But an idea that i want to buy a carbon bar and I will read an article which one will be right for me is plain dumb.

And this article on NSMB with making a case for 16 back sweep is just plain madness.
• 5 0
@WAKIdesigns: I can do the numbers to a certain point to get an idea of what I might want to put on my bike, but I don't need the strings and measuring tapes and all that. I don't need exact. I just need to be in the ballpark. I can try something for a little while, and if it seems odd or squirrely, I'll go buy something else. But you're right -- you pretty much have the option of 2-3 stem sizes and you pretty much know the types of bars you like. It just does not have to be this hard.
• 13 0
@WAKIdesigns: The idea that science cannot inform bike fit would seem to be utter bologna. Yes, certainly personal preference should play some role, but this preference still has to interact with the laws of physics.

As a counterargument to your "no article can help you with your injury," I will mention that over the summer I developed wrist pain from riding that was severe enough to stop me from riding for several weeks. I read the NSMB article you were quick to disparage, bought bars with 12* backsweep, and voila I can ride again.

Sure, no article can capture the perfect setup for everyone. But to stop trying to quantify what works for modern mountain bike fit entirely, and go just based on "try a lot of setups" is clearly garbage that most people will not be able to afford.
• 6 20
@jkowitz: you can keep your garbage to yourself. Three stems and three bars cost no more than 350\$, and over the course of 5 years or so is nothing. Again and again and again, most people and most racers run stems and bars thqt are 40/750 withing 10mm range. You obviously miss the limitations of “science” which I haven’t found much of in this article or anything bicycle related, particularly in MTB. I personally don’t shit up and nod as soon as I hear the word “science”. Sorry...
• 5 1
@WAKIdesigns: My hands and wrists are very happy that Hayes/Answer makes a 20 degree sweep bar. Now if they would only make it WIDER!
• 3 1
@WAKIdesigns: Imperial stems. The next marketing ploy.
• 4 0
@WAKIdesigns: BMX has had increments like that for quite a while.

Not a big deal.
• 1 0
I believe there is a place for bike fit in MTBing. Unless you assume that everyones body proportions are identical. I was having a hell of a time getting comfortable on a bike until I factored in body geometry and found out that I have a negative ape index and longer than average inseam and needed to compensate with a taller stack or higher rise handlebar. I tried several trail and error setups before figuring out that the science of bike fit (through measurement of body proportions) was able to answer the question.
• 2 7
@Paxx: @WoodenCrow: do you have them on a fat bike, Enduro or a DH bike? If the latter, please send the pic...
@Paxx - look at a DJ bike. Then look at a XC bike. Then look at a DH bike. Come back to me when you find great bike fit for each of these... the differences in reach and stack are around 5-10cm. And some dumb mini adjustment in stem and bar will cover up for that? Yeah right... so yes there is a place for bike fit in MTB. It is called bike packing. Or fat biking.

Most importantly all these pitiful considerations of RC lack mentioning and thus understanding of biomechanics. Go take a curl barbell (you know, one that has many bends on it), put your hands in bends as if you would a handlebar with bigger sweep and try bench press your max with it. Good luck! Don't forget to bench press with normal bar though... Putting pressure on front wheel, ability to shift your weight over the bike?
• 4 0
@WAKIdesigns: Sorry, but you adjust bike fit for riding style. It is quite obvious that an XC bike should be set up differently than DH bike for the same person (i.e. dramaticaly different reach and stack). That's why Reach/Stack is quite poor measure of bike fit. The spread and angle is a bit better (this spread thing is what Sam Hill checks on a bike), but still this works for certain riding style. Like you have this rad/raad method by McCormack - this is a good method assuming you want to jump high on a bike and have a good range of movement, if speed is and stability are your preferences, then it's crap. Compromises everywhere.
But there are some basic rules which you can understand and measure and then you can reduce the number of trials required dramatically. You always have to check a few configurations by yourself though
• 2 5
@lkubica: but the principle remains the same. Applying force to the bike in practiced patterns of movements in order to make it do certain things. That is the thing allowing Brandon Semenuk to ride a Ticket for a minute only to throw it away and jump on a Session. Or our local dude to jump on one DJ bike and then take a BMX and do exact same tricks. If you change sweep of bars by 1-2degrees, stem/bar lengths by 1-2cm and it drastically changes your experience, you can’t really ride. You simply can’t adapt because you don’t have any good patterns of movement, you just got used to getting wobbled in a certain way by your bike, whatever it is. All good riders are known for their ability to adapt because the core of what they do on thw bike is solid and it is them being in control.
• 1 0
Of course there is a huge difference in the bikes that are built for different riding styles. I do believe that there is benefit to having a fit done for certain types of bikes if you are having issues with them though. I think this is less important on both extreme ends of the spectrum - DH bikes, DJ bikes, because you are not sitting and spinning, but anytime you are on a type of bike that requires long periods of time in a relatively static position such as a trail, XC, or enduro bike, there would be benefit.

Now even on those types of bikes, when you are up out of the saddle, then yes, you're correct, the fit matters less and the "practiced patterns of movement" will be more important. I don't think many people have fit issues when standing and going through a dynamic range of movement on the bike.

Most people that are interested in having a bike fit done are probably trying to find comfort while seated. I think that a lot of people ride in pain (even experienced riders) because they don't know how a bike should fit with their own body measurements.
• 5 3
Let's talk about why the bolt threads on my RF stem stripped when tightening with a torque wrench. Talk about sketchy. Apparently, you only get so many times of removal and install before some stems threadsstrip???
• 3 2
Also happened on my Raceface stem.
• 1 1
Just tighten by hand, cant be that diffucult
• 2 0
@zyoungson: but what's the use of a torque spec then?
• 1 0
@Mac1987: So manufactures can give people a guide for how far to tighten things, and have a get out for warranty claims if things are damaged from over tightening. Even world cup mechanics go without a torque wrench, its not that hard to feel when a bolt is done up properly.
• 3 0
If you're going to use a torque wrench, I'd check the calibration too. Requires a bit of trial and error if you have limited weight selections. Set your torque wrench to something you can try and replicate/click with weight on the other end of the handle. Put the square drive (or socket/bit) in the vice, drop a point load of weight at the end of the handle (I used dumb bells tied together with some cable), measure the length from the center of the square drive to the point load in your preferred units. Multiply this by your weight (I use in-lbs), and compare this torque to the torque your wrench is set at. If the torque from your weight load is higher or equal, it should click the wrench. If it doesn't, your wrench is calibrated incorrectly and will be overtorqueing fasteners, resulting in stripped threads.

I once stripped the cam journal cap taps during a valve clearance check on my SV1000, because I trusted a torque wrench that was not calibrated correctly. Lost a pair of underwear but I was able to helicoil it. Never again.
• 1 0
According to this article there is a limit on short stem-bar-steups. However I'm looking for exactly that myself in order to get my body-position further to the back of the bike.

Is it worth losing stable steering (eff. stem-length) for the benefits of body-positioning or not?
• 1 0
I think only you can determine that - we don't know about your physiology, current or proposed setup. I would say that you can counter the instability of a shorter stem with wider bars, or it may just be that you are on the wrong size bike and should consider sizing up a frame (or getting something custom made if it is that bad and you're already on an XL frame...).
• 2 0
Sorry, I re-read your comment and I should have put to go with a shorter frame, not larger, if your weight is too far forwards...
• 4 1
Losing stable steering increases agile steering which can be a good thing. Slackening your head angle or having a longer bike will add stability so you can compensate.
• 3 0
Agree with slimboy here.

Try a smaller frame size to utilize same stem that you have or even slightly longer.

And go from there.

No amount of thinkering with cockpit setup will help if you are in the wrong size frame.

My humble opinion (and trial and tribulations)
• 2 0
I don't know who down voted @SintraFreeride but he's right - there's a place for agility and a place for stability, and depending what the OP is working with and what he rides it might be an improvement... A slackening headset, offset bushings, etc may compensate for the lower stability of a shorter stem if the OP is looking to keep the stability of the bike the same and a wider handlebar isn't an option too...
• 1 0
Yep@slimboyjim:
• 1 0
Thanks for the many answers! I'm definitely on the right frame. I also agree with SintraFreeride. I probably need to find a compromise of stability, agility and body position.
• 1 0
Interesting reading. Now I think I will have to test rotation of my handelbar.

I have Syntace 30 mm stem with Syntace Vector 12 deg, 20 mm rise - so my worst setup can have - 8 mm effective stem length (or even more because my steering angle is 64,5 deg).

@RichardCunningham Have you measured Syntace Vector 780 mm, 12 deg, 10 or 20 mm rise?

www.syntace.com/en_GB/products/handlebar/mountain-bike/616/vector-carbon-superlight-high-10?c=84
or
www.syntace.com/en_GB/products/handlebar/mountain-bike/618/vector-carbon-superlight-high-20?c=84
• 2 0
this is interesting. I tend to run my bars rolled pretty far forwards, giving me more rise and less backsweep. According to the premise of this article, that would make my steering more stable. interesing.
• 1 0
Just recently changed from a 35 mm atlas stem and 800 mm sixc bars to 40 mm stem and 800 mm fatbar. The fatbar has a degree less backsweep and the plan was to get more weight on the front wheel with the same stack height but I've noticed a slight improvement in control and feel as well. On an alloy orbea rallon in large so it's long enough for short stems but just the 5mm increase coupled with the slight decrease in sweep has really improved the handling so maybe going as short as possible isn't always the best policy
• 1 0
This article is incorrect.. there is a huge difference between actual stem length and effective stem length, as effective stem length ignores the fact that the handlebars must still pivot around the steerer from the distance known as the actual stem length measurement.
• 2 0
I have seen lots of bikes sent out the door with the bars centered to the stem rather than the ground below. A top dead center line on the bars would be a good starting point.
• 1 0
There are some interesting points made, and getting actual measurement data for stem/bar combinations is on the right track, but you have to consider all the features that make up a bike's geometry (and at different suspension travel positions) to determine if the steering will feel "unstable" in certain riding situations. It's good to know that these things are easily overlooked as working together to define hand position, but to say that 20mm effective offset is ideal or a limit is misleading, although probably generally a good assumption for current mountain bike geometries. "Trail" measurements are basically never listed, but are one of the most influential dimensions during riding, and fork offset plays a factor here but is often not included in the discussion. Transition and others are now using a smaller fork offset to increase trail, so you have to look at all those numbers combined to understand stability. The amount of leverage you have at the hand grip as compared to trail, at different speeds, is also a huge factor. Stability changes at different speeds based on head tube angle, trail, and the rotational inertia if the wheel/tires you're running. I could go on, but as usual, the only numbers most people compare are geometry numbers that don't mean nearly as much without the whole swath of data for a given bike. #endrant
• 1 0
Very interesting article. Since I am facing my new bike Nomad is smaller than my expectation, I am thinking of replacing the current 40mm stem with 60/65mm one. I discovered that this article recommends more than 20mm effective stem length. And how long stem can I choose to the maximun for steering stability?.
• 3 1
First thing I did when I got my new bike (2017 Remedy) was swap the 45mm stem for a 60mm stem. Maybe I'm old school, but I just dont like the feel of short stems...
• 3 1
Totally with you @schulte1400. I recently got a Pivot Switchblade, and requested the 60mm stem. I have a fairly long torso and kinda needed the extra bit of reach, and a Large frame feels too big to me. I also have decided I am not a fan of wide bars. 760mm (which isn't that wide for many these days) feels too wide and I got taken down by a tree in tight quarters last week - clipped the end of the bar just hard enough to put me off-line. I have a pair of 730's I used to ride, going to try them on the bike before I cut down the 760 carbon grip supporter. Ride what feels good!
• 2 1
My current bar + stem setup makes the steering at 0mm (780mm + 20mm) and I don't feel it is unstable at all. I think bike overall stability (WB, HA, CS) play a bigger effect than just bar and stem.
• 1 0
just the parts you think look good, and mess with them til it feels right. I have a pretty long stem and some bars with a shit load of rise and sweep, but who cares about the numbers as long as it's comfortable to ride
• 1 1
Finally, someone made measurements right! thank you @RichardCunningham for popularizing this info across riders;

most of the people will not notices +- 1 sm of effective length, however on edge cases, using too long / short frame sweet spot could be found
• 2 0
If Fabian had a 15mm stem, or even a 20, wouldn’t his hands be behind the steering axis when accounting for back sweep? Or have I missed something?
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No, I think you got it.
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Anyone else remember the azonic O stem? Even the hammer stem was pretty short. They were available back in the early 2000's. Mind you we all rode super narrow (by today's standards) bars back then.
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This is only a Sales and Marketing issue, can't sell enough of them handlebars so they have to make up an article to make it seem that we are doing it wrong!
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@RichardCunningham I haven't read all comments, but shouldn't your measuring plate/deviceof the steering axis also be set at 66 degrees. If so, the steering axis will be at bit further back.
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How far did Fabians bars sweep back on that 15 mm stem?

Surely we've missed that important info? Or I have?

Or, was his stem bar combo set to 15mm in Front of axis? It doesnt read that way.
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@lister11, Without being able to measure his bar/stem it would just be speculation, but your assumption that his bar may have put his hands behind or at the steering axis with the 15mm stem is probably right.
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@RichardCunningham: cheers bru. Have a Good one.
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So, What Does All This Mean?

That everyone was running shorter stems that they thought, back to the fishing pole stem lengths right nowwwwwwwwwww!!!!
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Wooww you finally made an full article instead of short replying somehow my comment some days ago... Thanks for fully bring it in!
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Will you also make a second part wheer 1cm of stem equals to Xcm of handlebar?
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@PauRexs: that really wouldn't be possible, since, as RC pointed out in the article, different handlebars have bends in different places such that any two bars that may be listed as having the same rise, backsweep and upsweep are going to yield differing hand/stem positions. However, it could be done for each individual make and model.
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@kjjohnson:
Though similar, that isn’t a German flag by PauRexs name so there is the possibility that he is joking.
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@kjjohnson: Haha you r right. But he did point it this way some years ago. In some his last articles I asked him to point out again this and I d like to think this is the reason of this article.
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@LAT2: Haha No I wasn't... But as Catalan apart of sort of English humor we also embrace some humbleness
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@PauRexs: I was just poking fun at the guy further up the thread. Though for full transparency I have to admit that I like Germans and their humour (and machines, of course). I also like Barcelona.
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I've been saying this for a while now. I even coined the term "Effective Stem Length" - not sure if anyone beat me to it?
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three hats off to you, sir. and a tip o' the cap
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PB tech, when the industry isn't pumping out "new standards" for us to complain about.
• 7 3
All of this is wrong.
• 3 1
hey RC, i noticed that none of your measuring devices are starret. i mean, come on...
• 1 0
They look well seasoned
• 2 0
This is the exact reason I think one piece bar and stem setups are a piss take.
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Too much geeking just ride and feel what's comfortable to you. Riding is suppose to be stress free, let's just go out, ride with our buddies and have lots of laugh and fun.
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A simple diagram illustrating every angle and measurement you refer to would have made the article much more easily readable and understandable.
• 2 0
Its time to take that 580mm Hussefelt out of the cabinet again!
• 1 0
Curious how you actually measure the 5* upsweep on the bar when setting up for a test. Some sort of digital angle finder?
• 2 0
My stem had a short fling with my bar. They still together. True story.
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Who knows what type of grips are in the PDent image?
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Oh I see commencal. Wish I could still buy those
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How to spacers factor into this?
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Don't think, feel.
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Am I missing the "simple tool" promised to use to calculate all this?
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I missed it at first. Run the string shown and it *should* be around 20mm from center of stem to the string
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When you hear the crack on your carbon bars you know you've gone to far.
• 1 0
Another case of the pendulum swinging too far and then coming back again.
• 2 3
That Mondraker Foxy is the most gate-ishly disgusting bike I've seen in a while.
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Get a lazer
• 3 4
No mention of fork offset whatsoever...
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..or trail
• 1 2
For offset has no direct impact. Instead, fork offset is dictated by wheel size and head tube angle. The effective grip offset is different as it causes a self-centering effect due to the horizontal force induced by your hands, whereas fork offset causes a self-centering due to a vertical force. Basically, pushing forward on the handle bars (which you do) will cause a torque towards the center position, as long as there is some handle bar offset. If the offset is too large, you're going to have trouble steering. If it is too small, you'll have trouble keeping the bike running straight.
Of course all these forces are in a delicate balance to each other, but looking at this one number in isolation is perfectly valid.
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@Kainerm: Incorrect. Fork offset is the orthogonal distance the axle axis is as compared to the steering axis and is a fixed number for a given fork. That offset number COMBINED with wheel size and head tube angle defines trail. Then you can start looking at the sum of the moments about the steering axis to understand how the forces interact. This is even still a simplified explanation, because as you turn, you lean, and stability is affected by all of those dimensions but also by the rotational inertia of the wheel/tire you have, which is of course dependent on speed.
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Respecting those words @dirt-klaud:
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@endlessblockades: we've got a scientist
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@dirt-klaud: You didn't get the point, or at least didn't understand me:
Fork offset is not defined by wheel size and head tube angle, but dictated by it. Meaning, in order to get a proper figure for trail, you need a certain fork offset - depending on wheel size and headtube angle.
Fact is, fork offset is creating a force due to a different mechanism than handlebar offset, so it is not correct to try and correlate these two. The proper approach is to evaluate handlebar offset in isolation from fork offset and trail. Rather, what has a more significant impact is reach. With a higher reach, you will need a lower handlebar offset, otherwise the bike will be incredibly difficult to steer - even with a low trail figure. And if you don't have any handlebar offset, it will be difficult to keep the bike straight, even with a extremely long trail figure.

The point is that handlebar offset always creates a centering force (torque, actually) on the steering, irrespective of the leaning angle of the bike. Trail, in contrast, creates a force that wants to turn the bike upright with the relation to the ground. Which is a huge difference once the ground is not flat anymore: If you're riding an off-camber section, trail will cause the bike to steer uphill. Handlebar offset will keep the handlebar straight, greatly inceasing control in this scenario. It also increases stability under hard braking; here, the trail figure decreases dramatically (due to the compression of the fork and concurrent lifting of the rear suspension, the headtube angle gets a lot steeper). Simultaneously, the deceleration puts a lot of pressure on the handlebar - which in turn keeps the bike going straight due to handlebar offset.
The impact of wheel inertia is tiny in comparison - otherwise, stunts like whips or tabletops wouldn't be possible.
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@Kainerm: Forgot to come back to this...a lot of what you're saying holds up. I just fundamentally disagree with your statement that handlebar offset should be evaluated in isolation from anything else in the steering geometry because it's literally all based on torques about the steering axis. From there, you either don't understand or are using terminology that is confusing me, and either one means we're not getting anywhere so I'll agree to disagree. Most importantly, the fact that people are thinking about and discussing the implications of geometry changes is a good thing. Maybe one day we'll get to a consensus, but then we wouldn't have so much fun arguing on a forum...
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Copyright Lee McCormack.....
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