# changing stem



## isaak (Oct 17, 2010)

Recently i tried new bike in shop and local rep, after fitting me, suggested to swap stem from 110 to 90 as i was still bending and stretching to much for my age and condition.
I am 6'2" and the bike is size 61 , because of my long legs. 
Does such change ( bringing force on handlebar 20mm closer ) drastically destroys geometry and performance of bike?
Will it be more unstable , to sensative when stearing ? Or i will not feel much difference ?
Appreciate any input.


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## looigi (Nov 24, 2010)

IMO and experience, it won't make any difference at all. The dynamic behavior of the bike is governed by the rake, trail, steering head angle, and wheelbase. Where the bars are makes no difference. You can change the stem, put aero bars on it, flat bars, or whatever.


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## Alaska Mike (Sep 28, 2008)

I'd disagree, to a point. It will make the steering _slightly_ quicker, and whether or not you notice that is a personal thing. The larger impact will be how your body will be centered over the frame. If you're properly positioned as a result of the stem swap, the effects on everything else will likely be positive.

I did a 110mm to 90mm stem swap on my BMC last year as a result of a professional fitting, and it made a big difference in terms of fatigue on longer rides. Quality aluminum stems can be cheap (I got a 3T stem for $28 online recently), so it doesn't hurt to experiment and see what works for you.


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## isaak (Oct 17, 2010)

thank you, will try with both length


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## Allez Rouge (Jan 1, 1970)

I'll have to agree with Alaska Mike. After years of riding a frame I was sure was too large, I recently started working with a professional fitter, and the last two changes we made were 110 to 100 stem and then from 100 to 90. At very low speeds the steering is much more twitchy with the 90 than with the original 110. At cruising speed, it's better, but still somewhat more twitchy, perhaps because my overall weight distribution has changed. (The fitter also loaned me an 80mm stem to try; but fit-wise the 90mm proved short enough, and given my experience with the feel of the 90 I have no interest in going any shorter.)

Like Mike, I am a lot more comfortable on my too-large bike now, so the change has been worthwhile. It's an interim solution, however. My permanent solution will be to buy a smaller frame with a shorter top tube, and then revert to the longer 110mm stem that I started with.


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## isaak (Oct 17, 2010)

i would do the same, go for smaller frame but my problem, i am 6' 2" and legs are somewhat disproportional long. so if i go one size down the seat post must be pulled out very high (now it is about 3" higher then handlebar) and it will be even worse as i will be bending a lot.
the size what fits me is 61 , overall it is comfortable except would like little less stretch and bending as at my age of 67 not so flexible any more as when younger and have some problem in lower back. 
I asked rep if replacing stem insted of shorter with tilted few degrees but he told that shorter is better then tilted . is it true ?


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## looigi (Nov 24, 2010)

Allez Rouge said:


> At very low speeds the steering is much more twitchy with the 90 than with the original 110. At cruising speed, it's better, but still somewhat more twitchy, perhaps because my overall weight distribution has changed.


How much difference do you notice between riding on the tops of the bars or the hoods? That moves your hands forward by over 120mm. It also greatly increases the leverage because your hands are further much apart. Certainly there will be differences, but those are much greater differences than increasing the stem length 10 or 20 mm.


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## Camilo (Jun 23, 2007)

isaak said:


> i would do the same, go for smaller frame but my problem, i am 6' 2" and legs are somewhat disproportional long. so if i go one size down the seat post must be pulled out very high (now it is about 3" higher then handlebar) and it will be even worse as i will be bending a lot.
> the size what fits me is 61 , overall it is comfortable except would like little less stretch and bending as at my age of 67 not so flexible any more as when younger and have some problem in lower back.
> I asked rep if replacing stem insted of shorter with tilted few degrees but he told that shorter is better then tilted . is it true ?


What frame are you looking at? As a starting point you should be looking to find one with a geometry that helps you accomplish your fit goals: Relatively shorter top tube and relatively longer head tube? I'd start by looking at frames with longer head tubes because a longer head tube will allow you to fit a smaller frame (thus shorter top tube) without bad seat-bar drop consequences. Hope that makes sense. So it would be interesting to know which bike frame you're looking at and see if it's that type of frame or not.

I think you're on the right track in going with as big of a frame as you can get to fit you with fairly normal stem length and angle. Within any frame model, the bigger frame will not only require less seat post above the top tube, but also have a longer head tube than the shorter frame. These two factors work together to achieve less seat to bar drop. All in all will require less flexibility. This is more so with the "long head tube" type of frames.

A 90mm stem is absolutely normal and you shouldn't think twice about it. You can even go 80 and all but the most discriminating riders wouldn't notice anything seriously odd about it.

As you've probably learned, bars can can be raised through upward angle of stem AND spacer height. Don't be afraid to maximize the number of spacers under the stem as well as an angled stem. Again, the need for this is less if your frame has a relatively longer head tube.

As for getting the bars closer, be sure to consider short reach bars also. You can also find some that sweep backwards from the stem. I think Ritchey makes one called ?? Bio Max that does, but there are others.

All of this will add up to allowing you to fit your reach on a large-ish frame which is good not only because of your long legs, but also because you don't want a lot of seat-bar drop.

Although much shorter, I have similar fit issues - I'm late 50s and losing flexibility. I have legs a tad longer than normal for my height, combined with old injuries that don't allow me to straighten my arms fully. I bought a Felt Z frame similar to many other of that type and it allows me to more easily get my bars a little closer and higher so I can get a very comfortable fit w/o extremely short or angled stem. I've always used short-ish reach and drop bars so that wasn't a factor. I could have done the same with my old Cannondale CAAD frame, but it would have required a very steep angled and unusually short stem. I go just as fast downhill on this frame and feel much, much fresher and stronger on long rides and climbing.


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## isaak (Oct 17, 2010)

I am interested in Cannondale Synapse alloy 5, 
Trek 2.1 ( in H3 frame), 
Felt Z85 
and may be Giant Defy 1.
There is no problem to find any bike in size up to 58 around here
but, except Synapse, nobody carries in stock my size ( 61-62 ) as this size is not in demand .


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## PJ352 (Dec 5, 2007)

Camilo said:


> What frame are you looking at? As a starting point you should be looking to find one with a geometry that helps you accomplish your fit goals: Relatively shorter top tube and relatively longer head tube? I'd start by looking at frames with longer head tubes because a longer head tube will allow you to fit a smaller frame (thus shorter top tube) without bad seat-bar drop consequences. Hope that makes sense. So it would be interesting to know which bike frame you're looking at and see if it's that type of frame or not.
> 
> I think you're on the right track in going with as big of a frame as you can get to fit you with fairly normal stem length and angle. Within any frame model, the bigger frame will not only require less seat post above the top tube, but also have a longer head tube than the shorter frame. These two factors work together to achieve less seat to bar drop. All in all will require less flexibility. This is more so with the "long head tube" type of frames.
> 
> ...


Good advice here, IMO. Considering how a bike negotiates turns above about 5 MPH, IME there are no negative effects of running a shorter stem. And while adversely changing a riders f/r weight distribution can affect handling, assuming a frame is sized close to right (for a given rider), going from a 110mm to an 90 mm stem isn't a problem. 

I agree that the OP should be looking at bikes with relatively short ETT's and longer HT's - some LOOK's comes to mind, but there are others. 

Lastly, I disagree with the fitter that there's some benefit in changing stem length over angle. Both have separate, but related purposes.


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## cxwrench (Nov 9, 2004)

looigi said:


> IMO and experience, it won't make any difference at all. The dynamic behavior of the bike is governed by the rake, trail, steering head angle, and wheelbase. Where the bars are makes no difference. You can change the stem, put aero bars on it, flat bars, or whatever.


exactly...would your car steer differently if you changed the diameter of the steering wheel? no...your hands would be close together and that's all. it may change 'feel', but it doesn't actually make the handling any different.


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## Camilo (Jun 23, 2007)

isaak said:


> I am interested in Cannondale Synapse alloy 5,
> Trek 2.1 ( in H3 frame),
> Felt Z85
> and may be Giant Defy 1.
> ...


Yea, those are the type to look at, you're definitely on the right track. Another fairly commonly available is the Specialized Roubaix line. For a given size, they all have a higher head tube than a full on racing frame. I'd bet you can get any of those to fit you fine, so it might just come down to which dealer you like and which seems the best value to you. On the other hand, the "effective" or "horizontal" top tube dimension might be worth looking at closely. In my particular size, all of those had very close dimensions in effective TT and head tube, but there were some 5 mm differences. If you are really getting down to a sub-90mm stem and really pushing the stack height and angle of the stem, a 5mm shorter ETT or higher HT might give you some flexibility and options in later adjustments, so it might be worth looking closely at those dimensions on the charts. But they're all lnice bikes and pretty close in fit.

I didn't need to get quite that exact, so mainly decided on the basis of local dealer and availability. I'm extremely happy with my Felt Z, but I have no doubt the others are great too. Frankly, I probablyy would have gone with a Synapse frameset if I could have ordered one locally or found a price on ebay that didn't kill me after shipping. I was and am a big Cannondale fan having had a great relationship with my CAAD frame until I just couldn't get comfortable enough and had to do kludges getting just another inch height in the handlebars to get it to fit. But now I'm a big Felt fan, so there ya go.

Good luck. Comfort first. I don't believe there's any down side to this type of frame, even for full on racers since it's easy to get as aero as you want when you want. But for the rest of the time, happy, neck, arms, back and hips = happy legs.


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## Dinosaur (Jan 29, 2004)

I recently read an article about stem length (VeloNews?) and it said there was no scientific method to determine stem length. It comes down to what feel comfortable for you. I mess with my stems constantly, I have a collection of them, all 110's but in different rises. A stem will a higher rise will bring your bars up higher and closer. Also tilting your bars up a tad will make a difference. If you can, see if your LBS will let you try out a couple of stems so you can get an idea of what works for you.

If you look at clips for the Pro's there are a lot of different positions out there.


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## rx-79g (Sep 14, 2010)

cxwrench said:


> exactly...would your car steer differently if you changed the diameter of the steering wheel? no...your hands would be close together and that's all. it may change 'feel', but it doesn't actually make the handling any different.


Actually, it would. Ever driven a sports car with a 10 inch steering wheel?

Make the stem short enough and it will change how the bike feels because handlebars aren't just controls - they're rests for you arms and upper body. Steering resistance on a bike is minimal - what is there is purely a result of geometry - stem/bar lever arm, rake and steerer angle. Go from a 56cm top tube with a 80mm stem to a 51 top tube and 130mm stem and you will feel a difference.

That said, 90mm stems aren't pushing any sort of envelope. It may feel a hair different than a 110, but not squirrelly.


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## frdfandc (Nov 27, 2007)

When I first got my road bike, it came equipped with a 120mm stem on it. Way too long for me. I switched out to a 90mm right off the get go. This made things so much more comfortable. Then when I switched handlebars and shifters (from Shimano 105 to Sram), I dropped another 10mm on the stem to account for the different position of the Sram shifter hoods vs. the 5600 105 hoods.

Even by going with a 40mm shorter stem, I have not noticed any affect on the handling and steering input at all.


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## rx-79g (Sep 14, 2010)

frdfandc said:


> When I first got my road bike, it came equipped with a 120mm stem on it. Way too long for me. I switched out to a 90mm right off the get go. This made things so much more comfortable. Then when I switched handlebars and shifters (from Shimano 105 to Sram), I dropped another 10mm on the stem to account for the different position of the Sram shifter hoods vs. the 5600 105 hoods.
> 
> Even by going with a 40mm shorter stem, I have not noticed any affect on the handling and steering input at all.


But your position changed from stretched out to just right. If you were putting your weight on the two bars in the same way it would be a better test.


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## isaak (Oct 17, 2010)

my dealer for Synapse offered to try with different stems, no problem.
only now i am waiting for spring ,dry roads and get theoretically and mentally ready. 
thank you


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## Mr. Versatile (Nov 24, 2005)

It won't make a bit of difference in handling or steering. Bicycles & other single track vehicles steer by leaning over, not by turning the handlebars. The length of the stem means nothing except your comfort.


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## frdfandc (Nov 27, 2007)

rx-79g said:


> But your position changed from stretched out to just right. If you were putting your weight on the two bars in the same way it would be a better test.



My point was that I made a drastic drop in stem length without any stability/handling issues arising.


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## isaak (Oct 17, 2010)

being in engineering all life i would disagree about this.
upplying same force on different length arm will give you different effect in steering and handling as you move to or from front wheel center. .
to what degree and to better or worse....? it is another matter .
may be for recreational rider as me would not make much difference 
but this can be only checked out during test rides with stems of different length


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## cxwrench (Nov 9, 2004)

rx-79g said:


> Actually, it would. Ever driven a sports car with a 10 inch steering wheel?


a smaller than normal wheel, yes. 10"? they rarely put wheels that small in formula cars. race cars that use really small steering wheels do so because that's what fits in the cockpit. the wheel on my shifter kart isn't even that small. anyway, i've had small(er) steering wheels on a bunch of cars over the years, and it didn't change the steering geomety or weight distribution of the car. it doesn't make the 'steering quicker', that is taken care of by the rack and pinion or whatever steering mechanism is employed. it takes very slightly less time to turn the smaller diameter wheel, but it doesn't make the steering 'quicker'.


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## rx-79g (Sep 14, 2010)

Mr. Versatile said:


> It won't make a bit of difference in handling or steering. Bicycles & other single track vehicles steer by leaning over, not by turning the handlebars. The length of the stem means nothing except your comfort.


Then I guess we don't need headsets.


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## PJ352 (Dec 5, 2007)

isaak said:


> *being in engineering all life *i would disagree about this.
> upplying same force on different length arm will give you different effect in steering and handling as you move to or from front wheel center. .
> to what degree and to better or worse....? it is another matter .
> may be for recreational rider as me would not make much difference
> but this can be only checked out during test rides with stems of different length


Being an engineer all your life, you'll understand gyroscopic effects. If you understand that, you'll understand that changing stem length (assuming correct f/r weight distribution), won't adversely affect steering/ handling.

http://en.wikipedia.org/wiki/Double-wheel_steering_bicycle#


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## rx-79g (Sep 14, 2010)

PJ352 said:


> Being an engineer all your life, you'll understand gyroscopic effects. If you understand that, you'll understand that changing stem length (assuming correct f/r weight distribution), won't adversely affect steering/ handling.
> 
> http://en.wikipedia.org/wiki/Double-wheel_steering_bicycle#


I would suggest reading the "Rider control inputs" section of the link you so humbly posted for engineers everywhere. You might then move on to the section about the falacy of gyroscopic effects under "Other hypotheses".


Look folks, two wheeled vehicles turn like aircraft: Control inputs (handlebars) make changes to control surfaces (fork/wheel) that changes the attitude of the bike to establish a lean angle. That lean angle IS cornering. For a given lean angle and speed, wheelbase determines turning radius. The stability of the system comes from trail.

The feel of the controls on a bicycle come from the resistance to steerering by the head tube angle, and the length of the lever arm from stem and bar size. There isn't a high degree of resistance to steering, so it is more about the arc distance the bars need to move make a certain degree angle change. On top of that, as you approach zero stem length the system gets unstable because the body weight on the bars that helps point the wheel forward stops helping.

So longer stems allow a finer degree of control, and lower HTAs resist steering forces more. 90mm stems are not a big deal. BUT, if you had a chance to ride two bikes that fit you, had the same HTAs and traded stem length for TT length, you would notice a difference in which bike was easier to keep a given steering angle. 2cms, combined with a change in reach, is not going to make an important difference.


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## Gimme Shoulder (Feb 10, 2004)

I disagree with the leverage argument. Obviously, I don't disagree with the concept of leverage - only as it applies to this discussion. Yes, when the lever arm is reduced the amount of force required to make the mechanism turn increases. This is certainly true with the steering wheel analogy, because there is some force required to turn the wheel of a car to begin with. But, I don't think this is the relevant factor on the bike, because headsets turn pretty freely. Rather, I think the "twitchiness" or "quickness" some have mentioned is more to do with the rudder effect. Related to leverage, but having nothing to do with the force required to turn the mechanism. If you reduce the stem from 11cm to 9cm, you also reduce the amount of displacement required at the end of the stem to achieve the same angle of turn by the same ratio. An 11cm stem requires that you displace the end of the stem (turn the handlebars) about 2cm to achieve a 10 degree turn of the stem/wheel. An 9cm stem requires only 1.5cm to achieve the same 10 degree turn. It doesn't seem like much, but I believe you may interpret it as feeling quicker or more twitchy. That said, the shorter stem will shift your center of gravity slightly rearward, which may add stability, and also reduce the load transmitted to the bars. So perhaps somewhat offsetting effects.


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## PJ352 (Dec 5, 2007)

rx-79g said:


> I would suggest reading the "Rider control inputs" section of the link you so humbly posted for engineers everywhere.
> 
> Look folks, two wheeled vehicles turn like aircraft: Control inputs (handlebars) make changes to control surfaces (fork/wheel) that changes the attitude of the bike to establish a lean angle. That lean angle IS cornering. For a given lean angle and speed, wheelbase determines turning radius. The stability of the system comes from trail.
> 
> ...


I didn't post "for engineers everywhere", I posted for the OP. 

Also, I did read the rider control input section - along with the aforementioned section(s) before including the link. If you think it runs counter to my claims, I believe you're mistaken, so you may want to reread that section.

I do, however think you're 1/2 right about cornering. Lean _along with countersteering _(which I believe you neglected to mention) executes a turn. So again, in the OP's scenario, assuming correct f/r rider weight distribution, changing stem length won't affect steering/ handling.


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## rx-79g (Sep 14, 2010)

PJ352 said:


> I didn't post "for engineers everywhere", I posted for the OP.
> 
> Also, I did read the rider control input section - along with the aforementioned section(s) before including the link. If you think it runs counter to my claims, I believe you're mistaken, so you may want to reread that section.
> 
> I do, however think you're 1/2 right about cornering. Lean _along with countersteering _(which I believe you neglected to mention) executes a turn. So again, in the OP's scenario, assuming correct f/r rider weight distribution, changing stem length won't affect steering/ handling.


I read it. And the section about gyroscopic forces. Did you? It specifically states that "direct position control over steering angle has been found to be problematic", which is pretty much the opposite of saying that stem length doesn't matter.

I didn't mention "countersteering", I mentioned "steering", of which countersteering is one type. Moving the handlebars causes the bike to change attitude, with leaning acting as a secondary input. Don't confuse that with "lean angle", which is a steady state angle that happens after the control input has been put in and then taken back out. The length of the lever determines the level of sensitivity of any simple control, and bigger bars and stems are longer levers. They don't provide "greater leverage", they provide a larger arc to act on the same degree of steering.

Again, within a certain range this doesn't matter. But broad statements and put-downs do.


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## seacoaster (May 9, 2010)

Not sure if this is a matter of wording, but the Wikipedia article mentions that gyroscopic force as the *MAIN* stabilizing force has been discredited. One of the references attributes approx. 12% to gyroscopic force as keeping the bike upright, and points out that a moving bike will remain upright on it’s own for a period of time. Bicycle stability is a difficult analysis according to most of the references cited.

I sure am glad all of this stuff wasn’t published when I was a kid in the 50’s. I didn’t know that you had to move the handlebars to initiate a turn, keep weight on the front wheel to maintain stability, etc. We used to ride around the block without touching the handlebars. The turns have a pretty big radius, but it’s possible.


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## PJ352 (Dec 5, 2007)

rx-79g said:


> I read it. And the section about gyroscopic forces. Did you? It specifically states that "*direct position control over steering angle has been found to be problematic*", *which is pretty much the opposite of saying that stem length doesn't matter*.
> 
> I didn't mention "countersteering", I mentioned "steering", of which countersteering is one type. Moving the handlebars causes the bike to change attitude, with leaning acting as a secondary input. Don't confuse that with "lean angle", which is a steady state angle that happens after the control input has been put in and then taken back out. The length of the lever determines the level of sensitivity of any simple control, and bigger bars and stems are longer levers. They don't provide "greater leverage", they provide a larger arc to act on the same degree of steering.
> 
> Again, within a certain range this doesn't matter. But broad statements and put-downs do.


As usual, you're reading what you want into a statement. It's not a given that a shorter stem places the rider 'over steering angle', so (yet again) I'll stand by my belief that changing f/r weight distribution is what adversely affects steering/ handling. It's also my belief that (generally speaking), cyclists fit shorter stems to compensate for excessive reach (or put another way) the wrong sized frame, and when steering is twitchy, they blame the stem. Again, it's more likely a f/r weight distribution problem.

As far as any confusion is concerned, I'm afraid it is yours. I _steer _a car, I _countersteer_ a bike. There _is_ a distinct difference that's relevant to the topic, so IMO you were remiss in not mentioning it. Not a put down, merely a correction.


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## danl1 (Jul 23, 2005)

Gimme Shoulder said:


> I disagree with the leverage argument. Obviously, I don't disagree with the concept of leverage - only as it applies to this discussion. Yes, when the lever arm is reduced the amount of force required to make the mechanism turn increases. This is certainly true with the steering wheel analogy, because there is some force required to turn the wheel of a car to begin with. But, I don't think this is the relevant factor on the bike, because headsets turn pretty freely. Rather, I think the "twitchiness" or "quickness" some have mentioned is more to do with the rudder effect. Related to leverage, but having nothing to do with the force required to turn the mechanism. If you reduce the stem from 11cm to 9cm, you also reduce the amount of displacement required at the end of the stem to achieve the same angle of turn by the same ratio. An 11cm stem requires that you displace the end of the stem (turn the handlebars) about 2cm to achieve a 10 degree turn of the stem/wheel. An 9cm stem requires only 1.5cm to achieve the same 10 degree turn. It doesn't seem like much, but I believe you may interpret it as feeling quicker or more twitchy. That said, the shorter stem will shift your center of gravity slightly rearward, which may add stability, and also reduce the load transmitted to the bars. So perhaps somewhat offsetting effects.


You are getting very close to the truth here. There are offsetting effects here, because as the lever arm decreases, the amount of force required to affect a given change increases proportionately. So, whether a given rider experiences that as 'more twitchy' due to more effort required to make a change) or 'less twitchy (due to longer movements required to affect the same amount of change) depends on how (and how well) they are fit to the bike.

If there is relatively more weight carried on the hands, the bike will indeed feel twitchier. The weight being carried by the hands coupled to a higher effort will reduce the capability to make fine control inputs, while at the same time, the shorter arc length requires exactly that. A lot of over-controlling will result.

If there is relatively little weight on the hands, the bike will generally feel more stable, due to the higher force requirements to initiate a turn. This effect is pretty minimal, but it's there. Riders in this condition will sometimes complain that the bike feels 'sluggish' - hard to initiate, but once moving easy to turn/stabilize/whatever.

For a decently set-up and balanced rider, the two effects (increased leverage and decreased travel) essentially wash, and after a few minutes are perfectly adapted. And a couple cm's of stem position change the rider's CG almost not-at-all.

Frankly, this is way overthought. For simple hand comfort, we all move our hands up and down on between the ramps and hoods without even noticing the effect, or indeed that we're even doing it. That's a far larger change than these stem swaps contemplate.


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## danl1 (Jul 23, 2005)

rx-79g said:


> I didn't mention "countersteering", I mentioned "steering", of which countersteering is one type. Moving the handlebars causes the bike to change attitude, with leaning acting as a secondary input. Don't confuse that with "lean angle", which is a steady state angle that happens after the control input has been put in and then taken back out. The length of the lever determines the level of sensitivity of any simple control, and bigger bars and stems are longer levers. They don't provide "greater leverage", they provide a larger arc to act on the same degree of steering.


This is a chicken-and-egg sort of argument. Lean angle combined with rake and trail determine a turn's circumference: A leaned bike with wheels locked in-plane wouldn't turn at all, but a well-designed and balanced bike will easily form an equilibrium at a given combination of circumference and lean angle. So as a practical matter, we 'steer' a bike (that is, give it handlebar inputs) in order to stay in balance, and a bike 'steers' (that is, changes direction) by being leaned. 

In order to turn a bike then, one thing is required: The CG of the bike and rider has to be to the inside of the wheel track of the wheels on the ground. This can be accomplished one of two ways: By leaning into the desired direction of turn, or by steering (that is creating a steering force away from the direction of turn. That's countersteering, and it's the only input method for getting a turn initiated. (as compared to steering with ones' backside and head, which is how most course correction occurs.)

Once initiated, additional countersteering (it likely doesn't cross centerline, but is still outward to the current equilibrium steering angle) will allow us to make more lean and so a tighter turn, while turning the bars into the turn will bring the wheels underneath the CG, making us more upright, straightening the equilibrium angle and yielding a larger circumference of turn.

Actually trying to 'steer' a bike (turn bars left to go left) is road-rash inducing, every single time. Physics - it's not just a good idea, it's the law!  

(BTW, I have no earthly idea if I'm arguing with you or expanding on what you wrote. I do know that it's all easily provable with simple anecdotes and practical exercises, such as riding no-hands, binding a headset, or tapping the wheel in front of you with your front.)

I will make one apparent clarification, though: On the arc length vs leverage debate, there is none. Both factors change in inverse proportion to one another: Halving the distance from hand to steerer halves the arc length, and doubles the force required to effect the change, and vice versa. As mentioned in another post, how a rider subjectively experiences the greater force or smaller movement depends mostly on how they are balanced (hands-to-butt) on the bike.

Actually, I take that back. It probably depends mostly on what they expect to experience by the change. The placebo effect is very strong with this one, which is why it's such a point of contention.


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## rx-79g (Sep 14, 2010)

danl1 said:


> This is a chicken-and-egg sort of argument. Lean angle combined with rake and trail determine a turn's circumference: A leaned bike with wheels locked in-plane wouldn't turn at all, but a well-designed and balanced bike will easily form an equilibrium at a given combination of circumference and lean angle. So as a practical matter, we 'steer' a bike (that is, give it handlebar inputs) in order to stay in balance, and a bike 'steers' (that is, changes direction) by being leaned.
> 
> In order to turn a bike then, one thing is required: The CG of the bike and rider has to be to the inside of the wheel track of the wheels on the ground. This can be accomplished one of two ways: By leaning into the desired direction of turn, or by steering (that is creating a steering force away from the direction of turn. That's countersteering, and it's the only input method for getting a turn initiated. (as compared to steering with ones' backside and head, which is how most course correction occurs.)
> 
> ...


The arc vs. leverage thing is certainly true in terms of a tradeoff, but I think that the leverage, not matter what the HTA or stem length is, doesn't matter. It is simply too easy to turn the bar regardless of any of these factors. With steering resistance so low, the increasing leverage doesn't really factor into things, so the arc distance ends up being the only real factor, IMO.

You can steer a bike with just the handlebar. It is "countersteering", but anyone who's taken a motorcycle safety course has done just that alone to understand how steering works on two wheeled vehicles.

In the real world, we lean and (counter)steer. If you lean alone, the bike will countersteer. If you countersteer, the bike will lean. You'll only fall if the lean is the opposite of what you expect and you try to counter it.


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