Hi guys I ride a specialized allez which has a 130mm stem length,on long rides im uncomfortable reaching to the drops.im thinking of switching to a 90mm stem.will this have a positive affect
Yes, It's positive way, maybe 130mm stem is too long for you.
The change from 130mm to 90mm is very large. Ideally you would probably make changes in smaller increments, unless you are very certain about the changes. You may also want to change the rise of the stem to position the handlebars higher. That will bring the bars closer to you.
The decision you are making would be easier if you had an experienced bike fitter look at you on the bike and talk about these issues. That person should also be able to provide stems of different dimensions for you to test. You might find it a worthwhile investment compared to buying lots of stems, trial and error.
Its going to make steering a bit different - I'd go no shorter than 100mm.
If reach to drops is the problem, also worth taking a look at your bars. If you do not have "compact" bend (or short drop) bars, consider switching to something like Deda Zero (75mm reach/128mm drop), Fizik Cyrano R3 Bull (80mm reach/130mm drop) or Planet X Strada road shallow drop (a positively tiny 70mm/125mm).
100mm should give a nice balance feel to the steering.
I've upgraded my #1 from a 100mm to a 120mm stem to give me more of a race position on the bike. The difference in steering is quite big. The longer stem seems stable enough when i'm in the drops but goes a bit weird when i'm out of the saddle and on the hoods (usually on a steep climb or an acceleration).
If you get this with your 130mm stem then reducing its length will probably improve the feel of the steering.....in my opinion
The answer to whether 130mm is right or not will depend partly on the frame size and how well it fits you, stem length is just one part of the equation.
As said above, you could consider the shape and depth of your drops but have you thought about your saddle position or your own flexibility? And how long have you been riding drop handlebars?
I'd visit someone who can do a proper bikefit. That would be far more useful to you than blind suggestions on a forum.
How do you mean uncomfortable though, too low or too streteched out?
Both require different things to remedy.
If it came with a 130mm I imagine you've got something like a 61cmframe?
I knew I'd have slight issues with stem length when I bought my race bike. I have long limbs, but short body. Stem was I think 120mm and way too long for me. I like riding really quite deep in the drops (big saddle to bar drop and traditional shape bars), but the reach was just too much for me.
I bought a cheap short stem (85mm) off eBay to get a sense of what it would feel like and have never since taken it off - been very happy!
You may well find a shorter stem is what you need. The ideal solution is to get a proper bike fitting (not Halfords or a judge-it-by-eye LBS), but that's quite an expensive option. Or you could try my route of buying something cheap second hand on eBay and trying it for comfort. If you don't like it, but a different size on eBay). Little money wasted.
I wouldn't worry too much about the impact of length change on steering characteristics. If you find the reach comfortable, you'll quickly get used to it.
+1 for a professional bike fit.
Had one last month and can't recommend it enough. Best £65 I've spent. Stem change from 130mm to 90mm made huge difference to my comfort. Along with lowering the saddle and adding a wedge under the cleat on my left foot, I now have no back or knee pain.
Maybe some is psychological but 29 Strava PRs on my first 50km ride on a regular route after the fit and consistently beating those now.
I bought an adjustable-angle Ritchey stem ages ago to sort some fit issues. I actually didn't end up even fitting it, it's still boxed. It's an ugly thing, but if you would find it useful just to try out different positions, I could always sell it for a tenner +postage?