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The effect of a shorter stem

jonny_trousersjonny_trousers Posts: 3,588
edited June 2011 in Road beginners
I understand stem size can have a detrimental effect on bike handling and was just wondering what I might expect if I was to go a little shorter (for comfort's sake)? At present my stem appears to be 11.5 cm centre to centre and ideally I would like to drop a cm. Would that be okay?

Posts

  • graemehograemeho Posts: 36
    that would be just fine.
  • FlamezFlamez Posts: 105
    Yes but as the OP says what is the effect of a shorter or longer stem?
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  • pinkbikinipinkbikini Posts: 257
    I can't tell the difference between stems that are 1cm different from a handling point of view, but from a comfort point of view I can tell the difference.

    All the talk about a 'twitchy' front end with a short stem is exaggerated. I can feel a slight difference in handling on a stem that's 2cm different on the same bike, but only a very slight difference.

    Go for it - comfort is more important.
  • MattC59MattC59 Posts: 5,433
    A shorter stem will give you 'faster' steering. ie the distance which the end of the stem has to travel (along the arc described by the end of the stem) will be shorter ie The angle that is turned is the same, but the distance which the bars move will be less. In short, you have to put in less steering input to turn the wheel.

    When people describe steering becoming more twitchy (assuming all other factors remain the same, fork rake, head angle etc) they mean it becomes faster. A 10mm difference won't make a huge difference in the speed of your steering, but could make quite a difference to your comfort.
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  • SlackSlack Posts: 326
    I've just changed stems myself. The original on my bike measured 115mm (c to c), and after taking it off, I saw the length stamped on as 110mm! I replaced with a 100mm.

    At slower speeds - up to about 20mph - I cannot feel much difference in the steering speed. At faster speeds however, there is certainly a notable difference. It doesn't feel twitchy, just more responsive; a flick of the handlebars results in a slightly quicker direction change.

    The only downside to my new set-up, is riding no hands down hill at 30mph feels more likely to result in a tank slapper!

    All the same, I think the difference it makes in general terms, probably boils down to frame geometry.

    I wouldn't describe it as being more comfortable, for me it's about being able to hold a better position, relative to the saddle, to be more efficient. Is your stem flipped down or up? If it's down, it may be worth trying it flipped up.
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  • rick_chaseyrick_chasey Posts: 50,777 Lives Here
    People exaggerate the effect.

    Took me all of 20 seconds to adjust to my new stem which was a good 6-7cm shorter than my old one.
  • dawebbodawebbo Posts: 456
    People exaggerate the effect.

    Took me all of 20 seconds to adjust to my new stem which was a good 6-7cm shorter than my old one.

    6-7cm?!? What the hell length are/were you using?
  • MattC59MattC59 Posts: 5,433
    People exaggerate the effect.

    Took me all of 20 seconds to adjust to my new stem which was a good 6-7cm shorter than my old one.
    Wow, that's quite a change !
    Were you riding a chopper ?
    :wink:
    Science adjusts it’s beliefs based on what’s observed.
    Faith is the denial of observation so that Belief can be preserved
  • chunkytfgchunkytfg Posts: 358
    To get the riding position the same between my summer and winter bike I have a 2cm difference between stem lengths. Every time I go from one to the other I notice the difference but after about 400yards i'm used to it! You will notice it more out the saddle on the hoods initially.
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  • neebneeb Posts: 4,361
    Remember the position of your hands in relation to the steering axis isn't just down to the stem length, unless you are holding the top of the handlebar. The shape of the handlebars and the position and shape of the levers will make a difference too. It's usually quite possible to change the reach by a centimeter just by tilting the handlebars and moving the levers.
    The only downside to my new set-up, is riding no hands down hill at 30mph feels more likely to result in a tank slapper!
    That must be all in the mind - all the stem does is put the bars ahead of the steerer - if you're not holding the bars it won't make the slightest difference! Headtube angle, fork offset and trail might affect no-hands twitchiness, but the stem can't!
  • marcusjbmarcusjb Posts: 2,412
    Agree with those who say you won't notice the difference in handling changing a stem by, let's say, 20mm or so - or if you do, it will be something you adapt to within a few miles. It really doesn't make a big difference.

    Where it will make a big difference is the comfort - here you really can feel the changes - and comfort is pretty much the most important thing - so make the change, get comfy and don't worry about any effect (perceived or real) that it might have on steering.

    Obviously, if you are changing stem length by, let's say, 50mm - that will take some adaption - but I would suggest that there is something wrong with the size or set-up of the bike if you need such a drastic change to try and make it comfy.
  • Pickled PigPickled Pig Posts: 233
    neeb wrote:
    That must be all in the mind - all the stem does is put the bars ahead of the steerer - if you're not holding the bars it won't make the slightest difference! Headtube angle, fork offset and trail might affect no-hands twitchiness, but the stem can't!

    The further the mass of the bars are from the centre of rotation the greater the inertia of angular momentum, so bar movement will be affected by stem length, even if your not touching them.
  • SlackSlack Posts: 326
    [
    The only downside to my new set-up, is riding no hands down hill at 30mph feels more likely to result in a tank slapper!

    That must be all in the mind - all the stem does is put the bars ahead of the steerer - if you're not holding the bars it won't make the slightest difference! Headtube angle, fork offset and trail might affect no-hands twitchiness, but the stem can't![/quote]

    It is not in the mid Sir - I'm not talking censored here! There is definitely a difference for me in the feel of my bike, including no hands!
    Plymouthsteve for councillor!!
  • rick_chaseyrick_chasey Posts: 50,777 Lives Here
    dawebbo wrote:
    People exaggerate the effect.

    Took me all of 20 seconds to adjust to my new stem which was a good 6-7cm shorter than my old one.

    6-7cm?!? What the hell length are/were you using?

    It was a long one, and now it's a really short one.

    It's maybe 6-7 cm long? I just bought the smallest one there was.
  • PokerfacePokerface Posts: 8,640
    dawebbo wrote:
    People exaggerate the effect.

    Took me all of 20 seconds to adjust to my new stem which was a good 6-7cm shorter than my old one.

    6-7cm?!? What the hell length are/were you using?

    It was a long one, and now it's a really short one.

    It's maybe 6-7 cm long? I just bought the smallest one there was.

    So you went from a Boonen-esque 140mm stem to a 70mm one? Yes - that would be a massive change in fit and handling.
  • jonny_trousersjonny_trousers Posts: 3,588
    Thanks guys, that's good news.

    For me it's just to relieve a little pressure I am feeling in my shoulders (traps?). A 10mm drop sounds like just the job. Don't suppose anyone knows what size I should be looking at to fit onto a bog standard Condor Fratello steerer?

    Interesting to hear that actual size and stated size is not always the same, however. I'll take mine off and have a look if it is marked in any way.

    Cheers!
  • rick_chaseyrick_chasey Posts: 50,777 Lives Here
    Pokerface wrote:
    dawebbo wrote:
    People exaggerate the effect.

    Took me all of 20 seconds to adjust to my new stem which was a good 6-7cm shorter than my old one.

    6-7cm?!? What the hell length are/were you using?

    It was a long one, and now it's a really short one.

    It's maybe 6-7 cm long? I just bought the smallest one there was.

    So you went from a Boonen-esque 140mm stem to a 70mm one? Yes - that would be a massive change in fit and handling.

    It was big change in fit. Didn't notice the handling much.
  • marcusjbmarcusjb Posts: 2,412
    Thanks guys, that's good news.

    For me it's just to relieve a little pressure I am feeling in my shoulders (traps?). A 10mm drop sounds like just the job. Don't suppose anyone knows what size I should be looking at to fit onto a bog standard Condor Fratello steerer?

    Interesting to hear that actual size and stated size is not always the same, however. I'll take mine off and have a look if it is marked in any way.

    Cheers!

    I run a 90mm on my Fratello - but that works for me - may not for you!

    It might be worth dropping into Condor if you can and sitting on their jig again to try different stem lengths and how they fit.
  • keef66keef66 Posts: 13,286
    "It is not in the mid Sir - I'm not talking censored here! There is definitely a difference for me in the feel of my bike, including no hands!"

    I'm wondering if it's because the headset bearings are loaded slightly less than they were, having presumably removed / replaced the top cap during the stem swap?? Any headset noise / movement?
  • SlackSlack Posts: 326
    keef66 wrote:
    "It is not in the mid Sir - I'm not talking censored here! There is definitely a difference for me in the feel of my bike, including no hands!"

    I'm wondering if it's because the headset bearings are loaded slightly less than they were, having presumably removed / replaced the top cap during the stem swap?? Any headset noise / movement?

    Maybe! I'm paranoid about overloading the bearings, so tend to under do it, so to speak. There's no play/noise in the headset. I may give it a tweak and see what happens.
    Plymouthsteve for councillor!!
  • neebneeb Posts: 4,361
    neeb wrote:
    That must be all in the mind - all the stem does is put the bars ahead of the steerer - if you're not holding the bars it won't make the slightest difference! Headtube angle, fork offset and trail might affect no-hands twitchiness, but the stem can't!

    The further the mass of the bars are from the centre of rotation the greater the inertia of angular momentum, so bar movement will be affected by stem length, even if your not touching them.
    You'r right of course, and I stand corrected in theory - but surely this is difference will be so tiny as to be practically non-existent compared to the other forces acting through the forks / steerer etc when you are going downhill? Or perhaps it is one of those situations where everything is in equilibrium and even a minute force can make a significant difference?

    Interesting anyway.
  • jonny_trousersjonny_trousers Posts: 3,588
    marcusjb wrote:
    Thanks guys, that's good news.

    For me it's just to relieve a little pressure I am feeling in my shoulders (traps?). A 10mm drop sounds like just the job. Don't suppose anyone knows what size I should be looking at to fit onto a bog standard Condor Fratello steerer?

    Interesting to hear that actual size and stated size is not always the same, however. I'll take mine off and have a look if it is marked in any way.

    Cheers!

    I run a 90mm on my Fratello - but that works for me - may not for you!

    It might be worth dropping into Condor if you can and sitting on their jig again to try different stem lengths and how they fit.

    That makes a lot of sense. I was thinking about buying online to save myself a few quid, but I'm going to get a wider set of bars when I take my bike into Condor for a service in a couple of weeks time, so it seems like a good idea to measure it all up at once.
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