I'm switching from a 110 stem to a 90. Its just too long. Question is, will I notice any difference in steering? I'm guessing not.

If not, would someone notice a difference from a 120 to a 70?

A 110 to 90 won't be much difference to make a drastic change in handling. A 120 to 70 is a totally different kettle of fish.

Not much. The 110 to 90 may feel a little weird at first, but everything else should be fine.

The steering will be a little quicker due to the shorter lever.

Your weight distribution will change and that will affect handling a bit. You may find that you need to bend your elbows more to get the weight on the front wheel so the bike feels balanced.

i thought you already just went to a smaller frame.

From a fit point of view, if you have the ability to do so, you might try a 100mm first. Lots of times the LBS will let you swap out old stems from a parts bin, while you're deciding.

I did, but because the mono link saddle doesn't come in a zero offset, it has me back a bit, so I'm going with a smaller stem to compensate, it isn't much, but where I'm putting my hands, and whats comfortable, it measures to be around a 90...I could probably do 100 but I'm ok with a little shorter, I can then drop it a bit.

I ride a 90mm stem on my road bike and 140mm on my MTB. this gives identical reach to the center of the bars. both bikes steer, brake and corner just fine.

it also has given me scornful looks from both roadies and MTBers. more on the MTB to be honest, a long stem just blows minds when you have a lot of people riding 70mm to BMX stems.

TL;DR
do it. my road bike had a 110mm stem and I went to 90. start with a cheap FSA stem and get your bling later after your fit is locked in.

ride the 110mm for a while.

also, if you cant get to your previous seat position, get a different post and saddle. were you fit with kops? maybe this is the better position anyway. folks tend to err sitting too high and forward with too short a reach. dont make those mistakes.

I went from a 120 to an 80 and twitched all over the place when I got above 30 mph, and the handling was so shaky that I couldn't even hold my line while reaching for a water bottle. It was better with the longer steam, but the reach was too much and my hands were constantly going numb (along with other appendages). I now have a custom bike that actually fits and distributes my weight properly, and the difference is night and day. I might suggest that if you need such a short stem, you're on the wrong bike.

120 to 80 is exactly double the amount of change DDF is talking about making.

I don't think there will be any deaths at 90mm.

Iwent the other way to get more down and longer arm reach - it feels great to me. Every fit is different.

I'm comfortable now for the most part, and its not too bad, but I think coming back a little will help, My saddle position and height have my legs dead on where they need to be.

definitely just give the current setup some saddle time.

i use a 80mm stem and a 110mm stem to get the same reach. a shorter stem and longer top tube is not a problem, but shortening your actual reach is not going to allow a good rider to stretch out.

but if I'm going to drop the stem a shorter one will be better...because I'll be extending my reach...or else I'd go with the 100 if I were going to keep it at the same height...the plan is obviously to slam it

then extend your reach.

I went from a 110 to a 100 and noticed no difference at all - so I am assuming the 90 will be similar. You may notice it for about 15 minutes, but otherwise I don't see it as that big of a change. If you were that concerned buy a cheaper stem to try out, then upgrade and sell the cheap one - it would be a cheap way to make sure.

The beginning of the year I went from a 120 to an 80 on a Synapse. I was fitted by my LBS and discussed quite a bit before changing the stem. I needed to be a bit more upright due to a bad back. It put me in a better position on the hoods for comfort and I did not find any noticeable difference in the handling but I don't race if that makes a major difference.

I went from a 105 to a 90 and after a couple hours of riding and my balance readjusting a bit, I can't say that I notice my steering to feel much different. Maybe a smidge more responsive at speed and that may be more to just being in a better position. Its definitely not any less stable.

don't listen to your wife, she's just making excuses to not hurt your feelings. size definitely matters.

If you are not moving your saddle or the position of your body on your saddle the stem length will have litlle effect on weight distribution and therefre handling. If the long reach caused you to sit way forward on your saddle and the shorter stem lets you move back on the saddle there will be a more significant change in weight distribution then you may have an effect on handling depending on where you were at. Stem length alone in my experience, as I have posted before has virtually no effect on handling. If you ride with no hands what is the effect of the stem lenght on how the bike handles?

I don't think I'd be taking sharp corners hands free, but I'm not moving my position on the saddle, I'm sitting exactly where I need to be now.

Huh...

"would someone notice a difference from a 120 to a 70? "

I have ridden everything from 90 to 130mm and it made zero difference to handling but a big difference to fit. Those that say you are shortening the lever arm must ride their bikes funny, last i looked the handlebar is the lever that your arms push and pull. At the small (few degree) movements while cycling at speed the stem length is insignificant as a lever in steering. No one would blink if you changed bar widths by 20mm. Of course some people will fit a short stem and feel twitchy and conclude that short stems are twitchy - all they have proven is that the wrong length stem for them felt twitchy

You have said it is not possible to position your saddle where you want therefore you are changing the stem to compensate. The stem length is independant of saddle position and cannot compensate for a incorrectly positioned saddle. Sounds like you may be making a poor adjustment to compensate for another poor adjustment. Think carefully