bt

sorry, was asleep in class the day they taught this.

mike868y

just guesing here, but I could think if anything it would decrease stability by placing more of your weight in the front of the bike. I could be totally wrong though.

Campag4life

In theory it slows the steering response however bike geometry trumps stem length in net effect to handling.

Ratfish

I went from 110 to 80 and I didn't notice anything in steering ability; you can either steer or you can't.

CrimsonKarter21

I'm pretty sure it does, but then again I only know by comparing between two bikes with different geometries.

DaveSSS 

A large change in length from an 80 to a 120 only increases the steering arm length by about 15%. At any normal speed, a bike is turned just like a motorcycle. You push on the right side of the bars to countersteer, the bike leans to the right and turns right. The bars only move a few degrees at most to complete even a tight turn. Most people think a longer stem makes the bike steer a little slower.

Changing stem length, by itself, makes almost no difference in the weight balance of the bike. To increase the weight on the front lower your torso angle or move the saddle forward.

Put a scale under the front wheel of a bike sometime. The weight goes up dramatically as you lower the torso from an upright position to a horizontal back position.

redtires

Yeah, it really won't affect the actual stability of the bike. What it will do though is have an effect on how comfortable and stable you feel on the bike, which is a big deal. In a proper position, you will have far greater control of the bike. When your comfortable, you bring almost all the stability to the ride. Depending on how big a change you make, you may feel different for a bit...but if it's a positive change for your body, you won't notice it after about ten minutes of riding.

urbanknight

Not much if any, and it wouldn't be worth it to compromise the fit of your bike.

buggg

i would say yes, but you probably wont notice on the road.

i was using a 130 most of this year, and trying to ride the rollers a few times a week for leg speed intervals. for kicks one day i decided to try and make the rollers more comfortable by switching to an 80mm stem(quill stem, could raised up higher then my 3ttt) and it seemed a little more difficult to control.

Bacana

I went from a 90mm to a 120mm on a bike, and noticed a huge difference--for me, the bike was much easier to control with a longer stem. I'm guessing it has to do a lot with my fit on the bike, though, so I wouldn't necessarily expect others to have similar results.

ShooterK2

I switched from 100mm to 80mm and couldn't tell any difference in handling.

hoodooguru

I switched from a 110 to a 130 and was surprised at how better the handling was particularly in high speed cornering.

nitropowered

I'd say its negligible. Initially you may feel a difference just because you changed something, but in few days you will get used to it and it'll all be the same.

Thats unless you have some major fit issues like too cramped on the bars, or too stretched out to be able to handle the bike appropriately

kwrides

Interesting. I expected a bunch of "yes's" because I use a 90mm and I've had more than one person ask me if it made my bike feel twitchy.

FWIW - it doesn't

Grumpy McTrumpy

A longer stem means you will move your hands more in order to steer the bike the same amount as before. If that means it is more stable to you then it is.

carpediemracing 

Longer stem - longer steering arc for bars, more weight up front.

At slower speeds it'll be a bit less responsive. Slower meaning like "I'm riding down the sidewalk behind people watching the race".

At higher speeds the front end will feel more solid. Higher meaning like 20-25 mph and higher.

Keep in mind that fit is more important. If you need more stability in your bike, don't slap on a longer stem arbitrarily. However, if you need to alter your position because you're becoming more cycling fit, a longer stem will help stabilize the bike at higher speeds.

One rider I fit:
https://suitcaseofcourage.typepad.com...-cleaning.html

https://suitcaseofcourage.typepad.com...ay-racing.html

His results (the fit wasn't everything, but it certainly didn't hurt) - 3 wins, a third, and something else I forget in the races after the fit.

He was certainly shocked when he first rode down his driveway ("slow"). He was pleasantly surprised while we were out riding ("normal pace").

cdr

rmwun54

I went from a 100mm to 120mm stem and what I notice was when riding down a fast winding road the front end feels way more stable than with the shorter stem. So I'm glad I did it.