How far are your bars behind your front wheel axle?

Discuss light weight issues concerning road bikes & parts.
rothwem
Posts: 41
Joined: Wed Jul 09, 2014 4:45 pm

by rothwem

I just got a bike fit, and the new position is a solid 10mm back at the seat and 30mm back at the bars. Apparently I have short arms for my height. It feels great on the trainer, but turning feels odd, like I don’t have any weight on the front wheel. I used to ride sportbikes, and I’m accustomed to “kissing the inside mirror” to weight the front when I turn, it’s harder to do that with the new position.

I measured my old bar position, and I was ~8cm behind the front wheel axle on that bike. My new position (math is fun, right?) is 11cm behind. It seems excessive, but maybe it’s normal?

Anyone here on a ~56-58cm bike? How long is your stem? And for everyone else, how far behind your front axle is your stem clamp?

by Weenie


dmulligan
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by dmulligan

What is your new stem size and what sort of bike is it?

I've read that stem sizes less than 80mm provide suboptimal turning on a road bike. If it's a TT bike then turning will always be awkward won't it?

How long have you been riding with your new fit? Try it for a few weeks. Any new position will feel weird for a while.

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rothwem
Posts: 41
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by rothwem

dmulligan wrote:What is your new stem size and what sort of bike is it?

I've read that stem sizes less than 80mm provide suboptimal turning on a road bike. If it's a TT bike then turning will always be awkward won't it?

How long have you been riding with your new fit? Try it for a few weeks. Any new position will feel weird for a while.

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Its a CAAD10, 58cm. The old stem is a 120, -6°, and the new stem is a 100, 0°. I've only done a couple rides on the new fit, so yea, I'm sure there's some acclimatization that will happen. I'm just wondering if my fit is particularly extreme.

zefs
Posts: 56
Joined: Sat Aug 05, 2017 8:40 pm

by zefs

I have tried 12,10 and now on a 8cm stem to compensate for a size larger bike frame. Steering isn't a problem on road bikes so even with a 8cm stem it isn't something you notice. If your position is neutral and you are not over-reaching then I would imagine the new position is correct.
If you notice a lot of weight on the hands then maybe you are in a too forward position. Too stretched and you can notice neck or lower back pain.

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kidrob
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Location: Belgium

by kidrob

rothwem wrote:Its a CAAD10, 58cm. The old stem is a 120, -6°, and the new stem is a 100, 0°.

What changed other than that?

I am 186m and run a 58 sized frame with Supersix geo with 110mm stem, so 100mm length doesn't sound odd at all.

I am sure going from 120 to 100 is quite some difference and ofc it does feel different, but I would just try it and see how it turns ut after some weeks. To make such changes that can turn out quite good is why you would go to a bike fit on first place anyways, no? ;)

Mr.Gib
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by Mr.Gib

Comparing to how others set their bikes up stem-wise is of no value to you. If your fitter was competent, than the fit is probably close. What your noticing in the change in steering feel is just the effect of a shorter stem. You will get used to it in a few rides and it won't bother you.

The real issue is your choice of bike. If you were an on a bike with endurance geometry, you would be able to keep your longer, lower angle stem and the steering feel you prefer. Perhaps going down to a 56 Synapse (to keep the discussion Cannondale) would be the solution.

My personal opinion is that short stems belong on small bikes. I can tolerate 120 mm but prefer 130mm. Never liked the feel of anything shorter than 120mm. FWIW (nothing really) most of my bikes are in the 56 - 57 cm size range and I use 130 mm, 10 degree stems, except for my cross bike which is a 58 with a 120 cm. I am 183 cm tall with longish arms.
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DMF
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Location: Sweden

by DMF

Perhaps the reality of the situation is that you just need a shorter reach frame, not a shorter reach stem and/or bar. Yes, you're numbers may be correct as far as contact points go, but if that leaves you with a bike that doesn't fit with regards to your weight distribution over the wheels and your centre of gravity with regards to the wheel axles (not to talk about how HTA and trail figures go into this), then maybe you've just stumbled into one of the many reasons why bike fitting purely on a trainer is a poor idea.

Alexandrumarian
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Location: Romania

by Alexandrumarian

I'm 185/88 with longish arms. I have an endurance geo 58 with 110 stem and 85 reach, it feels cramped with the saddle full back. I think I would be better on it with 120 or even 130. I also have a race geo 58 which has some 3cm extra toptube lentgh, 110/85 too. Saddle is centered, I sometimes feel slightly over extended but I wouldn't bother shortening it. 100 would look a bit off on such a large frame and I am very happy with how it handles/descends compared to the other one.

rothwem
Posts: 41
Joined: Wed Jul 09, 2014 4:45 pm

by rothwem

kidrob wrote:
rothwem wrote:Its a CAAD10, 58cm. The old stem is a 120, -6°, and the new stem is a 100, 0°.

What changed other than that?


He also scooted the seat back ~10 cm to allow for more recruitment of my posterior chain muscles while riding

DMF wrote:Perhaps the reality of the situation is that you just need a shorter reach frame, not a shorter reach stem and/or bar. Yes, you're numbers may be correct as far as contact points go, but if that leaves you with a bike that doesn't fit with regards to your weight distribution over the wheels and your centre of gravity with regards to the wheel axles (not to talk about how HTA and trail figures go into this), then maybe you've just stumbled into one of the many reasons why bike fitting purely on a trainer is a poor idea.


I agree, a shorter frame would be more optimal. However, the tricky thing is that even on the bikes with a shorter reach, the front-center is still ~600mm, which is what my CAAD10 is currently. The result is that my body will be in the same place relative to the front wheel still. The endurance bikes mentioned below have even longer front centers, so that front wheel will actually be more forward than before. However, what an endurance bike would prove/disprove would be whether the stem length is more of a factor than the weight distribution over the wheels.

Mr.Gib wrote:Comparing to how others set their bikes up stem-wise is of no value to you. If your fitter was competent, than the fit is probably close. What your noticing in the change in steering feel is just the effect of a shorter stem. You will get used to it in a few rides and it won't bother you.

The real issue is your choice of bike. If you were an on a bike with endurance geometry, you would be able to keep your longer, lower angle stem and the steering feel you prefer. Perhaps going down to a 56 Synapse (to keep the discussion Cannondale) would be the solution.

My personal opinion is that short stems belong on small bikes. I can tolerate 120 mm but prefer 130mm. Never liked the feel of anything shorter than 120mm. FWIW (nothing really) most of my bikes are in the 56 - 57 cm size range and I use 130 mm, 10 degree stems, except for my cross bike which is a 58 with a 120 cm. I am 183 cm tall with longish arms.


FWIW, I'm 185cm, and my seat height is 800mm.

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DMF
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by DMF

Certainly front-center is the key factor, rather than actual reach as HTA and sometimes fork offset varies by size across the same model, which is not to say there aren't other more beneficial geometries amongst other manufacturers lineups. From personal experience I would like to claim that when really forcing a bike into a corner then weight over the front wheel feels much more crucial than actual stem/bar length, regardless of bike type (CX/XC/Allmountain/DH/Road), but as for handling in a sprint situation, I would attribute a lot to the stem/bar length, or rather where the headset sits in this equation.

It's all a compromise when you get down the finer details.

youngs_modulus
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Location: Madison, WI USA

by youngs_modulus

I also have a motorcycle background; I used to pore over Keith Code's book. I feel compelled to suggest that your position over the front wheel doesn't matter as much as you suspect. It matters on motorcycles partly because they have way more suspension compliance than a 700x23 (or 700x42) bike tire. Bikes weigh so little that turn-in is effectively instant, and you don't need to weight the front wheel any extra to make it happen faster. If you want to do that, I'd recommend trail-braking a bit with your rear brake.

The change in CG based on your new fit is tiny; it doesn't change how the front wheel is weighted to any significant degree. The fit is just different and you seem to feel the that difference more when cornering. It's not a big deal.

Bernard Hinault used to promote a descending technique that involved making many "micro-turns" through sweeping corners. It was silly, but Hinault was a good descender, and he told a story about it that made sense to him.

Most bike road racers (including myself) will dip a knee to the inside just like motorcycle racers do. But we don't have any mechanical bits that we'll grind if we don't, and motorcycle racers do. Yet we do it anyway. I mean, I know it's useless, but that's what I learned and I feel slightly more secure in corners when I do it. I guess my point is that shifting your saddle back 10mm is not going to have a measurable effect on your cornering ability. But you can kiss your brifter all you want if it makes you feel more confident.

Hexsense
Posts: 370
Joined: Wed Dec 30, 2015 12:41 am

by Hexsense

youngs_modulus wrote:Most bike road racers (including myself) will dip a knee to the inside just like motorcycle racers do. But we don't have any mechanical bits that we'll grind if we don't, and motorcycle racers do. Yet we do it anyway. I mean, I know it's useless, but that's what I learned and I feel slightly more secure in corners when I do it. I guess my point is that shifting your saddle back 10mm is not going to have a measurable effect on your cornering ability. But you can kiss your brifter all you want if it makes you feel more confident.

Interesting, i tend to do opposite. I push the bike lean low to the corner but keep my body relatively straight up. It effectively move inside knee closer toward top tube and outside knee away from the frame as the result. Not sure if it affect anything it just my instinct to do it this way.

another note: i have
a bike with 71degree head tube angle, 579mm Front center, 395mm chainstay length
another with 72degree headtube angle, 571mm Front center, 410mm chainstay length

basically first bike has 8mm longer FC and rear wheel stay 15mm closer to the bb than 2nd bike. Although both bikes have virtually the same reach and stacks (+-2mm on each) I really do feel some difference in handling. But none are deal breaker or even annoying.

ddsg
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Joined: Sun Dec 08, 2013 10:30 pm

by ddsg

Would the stem angle also be a contributing factor?

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silvalis
Posts: 353
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Location: Brisbane

by silvalis

Hexsense wrote:
youngs_modulus wrote:Most bike road racers (including myself) will dip a knee to the inside just like motorcycle racers do. But we don't have any mechanical bits that we'll grind if we don't, and motorcycle racers do. Yet we do it anyway. I mean, I know it's useless, but that's what I learned and I feel slightly more secure in corners when I do it. I guess my point is that shifting your saddle back 10mm is not going to have a measurable effect on your cornering ability. But you can kiss your brifter all you want if it makes you feel more confident.

Interesting, i tend to do opposite. I push the bike lean low to the corner but keep my body relatively straight up. It effectively move inside knee closer toward top tube and outside knee away from the frame as the result. Not sure if it affect anything it just my instinct to do it this way.

.


You're probably doing the same thing, just to a lesser degree. If you lean the bike over, your inside knee is going to dip anyway, just to make room for the top tube, then the rest of your body will follow when you try to corner faster and sharper..
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by Weenie


Slammed
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Joined: Sun Feb 01, 2015 12:32 am

by Slammed

How far is my stem behind my axle? It's not. My stem's a good inch or two ahead of my front hub. I also have freakishly long arms and run a 15cm stem on a medium frame though.

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