Geometry question - not maths homework.

[woodsmith]

I occasionally get numb hands on the bike, though wierdly its not every ride and some days are worse than others, so I'd like to experiment with a slightly more upright riding position to get a bit of weight of the hands/wrists. Currentley running a Gusset Stache bar ( 35 degree sweep) on a 90mm stem. A line drawn between the centres of two bar ends passes approx 20mm to the rear of the centre of the top cap .
So my question is, if I were to fit a shorter stem, 60mm for example how would it affect the feel of the steering? Twitchier? Would a straight bar with a short stem and a swept bar with a longer stem which both put the bar ends in the same position in relation to the steering access have the same or a very different feel ( apart from physical hand-wrist position)?

[fatbikephil]

If your hands are already on a line 20mm to the rear of the steering axis with a 90mm stem, a shorter stem will put them further away from the axis, increasing the amount of effort required for a given torque input into the forks - less 'twitchy' in effect, but more effort to change the front wheels direction. It's the sort of thing that is hard to explain but if you draw it all out on graph paper it's clearer - think vectors!

Higher is maybe better than shorter, stem wise? Plus shoving your seat back so your rear acts as more of a counter balance, reducing pressure on hands.

[ootini]

Check what you're wearing... an old jacket of mine was very slightly tighter around the shoulders, and would cause Numb / tingly hands by restricting blood flow up around the armpit area.
Just a thought

[Bearbonesnorm]

a shorter stem will put them further away from the axis,

You sure Phil?

[fatbikephil]

a shorter stem will put them further away from the axis,

You sure Phil?

In his case Stu as his hand position is already behind the stem - so a shorter stem puts them further back. (goes to get bit of graph paper)

[Bearbonesnorm]

In his case Stu as his hand position is already behind the stem - so a shorter stem puts them further back. (goes to get bit of graph paper)

With you Phil, I'd kinda missed the bit about hands behind the centre.

[The Cumbrian]

This is very specific, with a sample size of one (me), but I had to pack in mountain biking in my twenties after a bout of carpel tunnel syndrome. I returned to it a few years ago when my son showed an interest and had the same issue, despite my new bikes being more upright than my old 90s mountain bikes. I've ended up using a riser stem and Jones riser bars which have raised the bars to just above the level of the seat, which reduces the pressure on my hands and gives a different grip angle.

[landel]

I've an old back injury which caused me to put a lot of pressure on my hands. Same as The Cumbrian, I've found that raising my handlebars above the seat level has really helped along with On-One OG bars (backswept like the Jones). I also use Ergon grips to spread the load. The combination works well and no problems since.

[boxelder]

I occasionally get numb hands on the bike, though wierdly its not every ride and some days are worse than others

I'd be looking for other causes, I think. I sometimes get hand discomfort on my drop bar bike, but usually when my front tyre pressure is too high??

[woodsmith]

Thanks for all the replys. Bit of an update.

Higher is maybe better than shorter, stem wise? Plus shoving your seat back so your rear acts as more of a counter balance, reducing pressure on hands.

Moved all the spacers under the stem and managed to raise the bars about 3/4". Bar ends are now about 3/4" above saddle height. The saddle is already as far back as it will go and the seatpost is a setback one.

Check what you're wearing... an old jacket of mine was very slightly tighter around the shoulders, and would cause Numb / tingly hands by restricting blood flow up around the armpit area.
Just a thought

Interesting idea but it happens regardless of what I'm wearing. It does happen more when wearing winter gloves which are a very snug fit.

I've an old back injury which caused me to put a lot of pressure on my hands. Same as The Cumbrian, I've found that raising my handlebars above the seat level has really helped along with On-One OG bars (backswept like the Jones). I also use Ergon grips to spread the load. The combination works well and no problems since.

I should of mentioned I'm already using Ergon grips.

I didn't win the cheap 60mm stem on fleaBay so I'll continue with the raised bars for now. Only managed one 25 mile ride so far but there was less numbness. Not conclusive as its been an intermitent issue, and a far from crippling one at that. I'm still interested to try a shorter stem when something cheap turns up. At which point I'll come back to yu with suggestions for a new saddle as my arse will no doubt start to hurt due to the more upright riding position.