Stem angle question

Ghost Rider

I currently have a very short stem on my road bike - 75mm, I think. It fits me comfortably but I do find it a bit twitchy, especially on descents.

I've noticed that the existing stem is pretty much flat - as in, parallel to the ground. So I'm figuring that if I was to try a longer stem - say 90mm - then a certain angle of rise might compensate to some extent for the extra 1.5cm stretch.

Will this work? Or is it just a crazy dream?

If the former, what angle should the stem be?

Morgan

35 degrees.

That would look terrible.

And would raise your handlebars a lot.

Maybe you just need a smaller frame.

Ghost Rider

I don't think I want to use the stem angle to totally compensate for the extra stretch (if that's what it proves to be) because that would negate the effect of a longer stem in the first place, would it not?

I was wondering if a 90mm stem with, say, a 10 degree rise would be some kind of compromise i.e. give me a bit more stability without requiring much more of a stretch...?

Morgan wrote: »

35 degrees.

That would look terrible.

And would raise your handlebars a lot.

Maybe you just need a smaller frame.

victorcarrera

Ghost Rider wrote: »

twitchy, especially on descents.


If the former, what angle should the stem be?

Before you buy a new stem you could try flipping the existing one over to raise the bars a little. If its flat a present it is likely to be 6 or 7 degrees above horizontal when flipped.

Stem Length: As a rule of thumb when you are riding comfortably on the drops the front wheel hub should be hidden behind the handlebar.
From my own experience with my own bikes I have found twitchy steering caused by one or a combination of the following.
1. Stem too short.
2. Loose headset.
2. Handlebars too narrow.
3. Flexing of front fork.

Ghost Rider

Actually, scratch my last question. I've just found a chart that tells me what I need to know. Here it is for anyone else who wants it:

http://www.habcycles.com/stemfit.jpg

Ghost Rider

I'm almost certain it's the stem. 75mm is pretty short for a road bike.

Flipping it is a good idea - will try that and see how it feels.

victorcarrera wrote: »

Before you buy a new stem you could try flipping the existing one over to raise the bars a little. If its flat a present it is likely to be 6 or 7 degrees above horizontal when flipped.

Stem Length: As a rule of thumb when you are riding comfortably on the drops the front wheel hub should be hidden behind the handlebar.
From my own experience with my own bikes I have found twitchy steering caused by one or a combination of the following.
1. Stem too short.
2. Loose headset.
2. Handlebars too narrow.
3. Flexing of front fork.

niceonetom

Ghost Rider wrote: »

I've noticed that the existing stem is pretty much flat - as in, parallel to the ground. So I'm figuring that if I was to try a longer stem - say 90mm - then a certain angle of rise might compensate to some extent for the extra 1.5cm stretch.

What matters (in terms of handling characteristics) is the horizontal distance the handlebars are in front of the axis of rotation of the fork - not the actual length of the stem. Using a longer but more angled stem might not actually increase the distance from this axis at all, and might only have the same effect as using an equally short stem but further up the steerer tube. Is that intelligible? This is the kind og thing best explained by a diagram...

Sounds like, gulp, your bike is a bit big for you. Maybe you could put a longer stem on it (stems should always be horizontal - anything else just looks wrong!!) and work on your flexibility?

Ghost Rider

Yeah, that's intelligible alright. I'd pretty much figured that out about the angle from the axis. What I might try is a slightly longer stem positioned slightly higher up the steerer tube since that is, in effect, what I'd be doing by using a longer, angled stem anyway.

niceonetom wrote: »

What matters (in terms of handling characteristics) is the horizontal distance the handlebars are in front of the axis of rotation of the fork - not the actual length of the stem. Using a longer but more angled stem might not actually increase the distance from this axis at all, and might only have the same effect as using an equally short stem but further up the steerer tube. Is that intelligible? This is the kind og thing best explained by a diagram...

Sounds like, gulp, your bike is a bit big for you. Maybe you could put a longer stem on it (stems should always be horizontal - anything else just looks wrong!!) and work on your flexibility?

Lumen

I'm not sure that changing stem length will make your bike less twitchy.

It depends what's causing the twitchiness.

A longer stem will put more of your weight on the handlebars, which might make it feel more twitchy.

I'd start by checking the headset compression and alignment of stem and wheels.

You say it's twitchy on descents. Are you descending in the drops or on the hoods?

I've read that lowering the handlebars (i.e. stem down the steerer) can improve the feel of descending, though I'm not entirely sure why.

Ghost Rider

Hmm. You challenge some of my deepest held convictions... or, if not convictions, notions. How could a longer stem make the steering more twitchy?

How do I check the compression of the headset? Or what is the ideal? I seem to recall hearing that that nut should only be "loosely tightened", for want of a better phrase. Is that not right?

Generally I descend on the hoods, by the way.

Lumen wrote: »

I'm not sure that changing stem length will make your bike less twitchy.

It depends what's causing the twitchiness.

A longer stem will put more of your weight on the handlebars, which might make it feel more twitchy.

I'd start by checking the headset compression and alignment of stem and wheels.

You say it's twitchy on descents. Are you descending in the drops or on the hoods?

I've read that lowering the handlebars (i.e. stem down the steerer) can improve the feel of descending, though I'm not entirely sure why.

Lumen

Ghost Rider wrote: »

Hmm. You challenge some of my deepest held convictions... or, if not convictions, notions. How could a longer stem make the steering more twitchy?

My last bike had a 90mm stem. My new bike has a 130mm stem. The new bike is twitchier. I don't claim to understand why - there are too many variables. Maybe I'm leaning on the bars more, so my inept motions have greater weight behind them?

Ghost Rider wrote: »

How do I check the compression of the headset? Or what is the ideal? I seem to recall hearing that that nut should only be "loosely tightened", for want of a better phrase. Is that not right?

The headset should be tight enough that there is no play (i.e. when you bang the front wheel on the ground using the handlebars), but not so tight that the bars feel gloopy when you lift the front wheel and swing from side to side.

Ghost Rider wrote: »

Generally I descend on the hoods, by the way.

Don't do that, particuarly in the wet. You get more braking force from the drops; if you come across a hazard whilst descending, changing from hoods to drops under braking is likely to end in tears.

petethedrummer

Lumen wrote: »

My last bike had a 90mm stem. My new bike has a 130mm stem. The new bike is twitchier.

And if you put at 90mm stem on the new bike it would be even twitchier again. With a shorter stem, smaller movements of your arms cause greater turning of the wheels. Needs a diagram, but it is the case.

blorg

Lumen wrote: »

I've read that lowering the handlebars (i.e. stem down the steerer) can improve the feel of descending, though I'm not entirely sure why.

Lowers your center of gravity perhaps?

Lumen

blorg wrote: »

Lowers your center of gravity perhaps?

Yeah, or maybe it just effectively lengthens the stem.

Anyway, as I understand it stem length is normally a fit issue, not a handling issue. If you are currently comfortable and then change your stem to improve the handling, you may end up uncomfortable.

I can see how a shorter stem would make travelling in a straight line on the flat more twitchy, but I think that descending at speed is a bit different, since you're steering with your bodyweight as much as anything.

ISTR that when I rode a motorbike (ok, scooter) I found it more natural to countersteer on fast bends.

I read this and confused myself further.