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10mm length increase in stem questions

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7.7K views 18 replies 15 participants last post by  bigdamo  
#1 ·
I have a 2021 Giant Trance in a small size. I am 5’5 and have always found my height to be at the cusp of small/medium but always went to the small. Currently I am running a 40mm stem (factory length) but I find the front end real loose and extremely light on the many technical climbs I do. This effect was amplified after trimming my handle bars down to 770mm (800 was just to wide for me). I did roll my handle my handlebars slightly forward but still find my butt sliding off the back of the seat while seated pedaling. My seat is slid (fore/aft) back to the max..

I have love the way the bike descends. Would a 50mm stem help reduce the slight wheeling on climbs? And would 10mm make the bike feel significantly different/or less stable on the down hill or just slightly?? Fyi, my fork has a 44mm offset.
 
#6 ·
It sounds like your seat is too far back. Consider your seated center of balance - sounds like it’s behind the rear wheels contact point on the steeps. Your balance is most to do with where your hips ‘live’ relative to where rear wheel touches the ground.

After seat is forward you might need a longer stem for comfort.

It might be you would be happier on a larger frame with shorter stem. :(
 
#7 ·
Increasing stem length will make the handling more stable overall and get your weight forward a bit on climbs. As above - saddle fore/aft position and stem height also make a difference, but try everything one at a time because you can end up chasing your tail if you change too much at once.
 
#8 ·
start moving your seat forward and see if that helps. i've been gradually moving my seat forward on my hardtail and it's helped my climbing. but i had to make sure my seat wasn't angled down because the forward seat position and forward sliding affected my knees.

if you're still wheeling when climbing, i would try lowering your handlebar height. remove the 5mm spacer or try lower rise bars if you can find some to borrow.

lengthening your stem will slow your steering and might make it worse for descending if you don't like how it puts more of your weight forward.
 
#9 ·
Get an inexpensive stem and give it a try. If you don't like it, you won't be out much money. If you do like it, you can either get a nicer stem, or just leave it as is and enjoy a cheap adjustment.

I went up 10mm in stem length on my new bike. The frame is sized right but I found that the front tire often wanted to push. Adding just 10mm in stem length really transformed the handling without significantly, adversely affecting descending. I can't say that an adjustment like that will always make such a big difference, but in this case, it did.
 
#10 ·
May as well try, but I have found that keeping the front end down on climbs is more a matter of climbing technique than stem length. You can always lean yourself forward even with a shorter stem. As someone else pointed out, where your saddle is fore/aft has more impact. Of course, you may find that sliding the seat forward makes you want a longer stem.
 
#11 ·
Yeah, a $15 ebay stem will tell you what you want to know. Or even better, a borrowed one.

Impossible for us to judge what effect it will have for you, in reality, on your bike in your terrain, in addition to other changes you might make. I'd def slide seat forward as recommended, too. But 10mm is about the minimum significant change to stem length you can make.

Had the same thing on my new hardtail...the 10mm really helped in my case.
 
#12 ·
There is a lot of sound advice here and I am much obliged.

I already adjusted the fore/aft positioning because I didn’t realize it was on the max. I also adjusted the handle bar roll to get me one mm or two. I am wondering if a handle bar with less back sweep would help (currently at 10). I’am getting some shoulder pain lately.

I am trying to focus on getting more weight over the front because it does handle and corner much better when I do. Dropping my wrist greatly helps on the climbs but I feel very upright.
 
#13 ·
I've gone the other way and taken 20mm off the stem on 2 different bikes and didn't feel the nose get lighter when climbing in either case. In both cases it felt better descending, though.

What did make a difference, in my experience, was pushing the chainstays from 435mm to 445mm. But unless you have sliding dropouts that's probably not very useful information for you.
 
#14 ·
A 50mm is still short enough so I don't expect it to throw handling off, I'd certainly give it a try. 10mm is enough to make a difference in a positive way though.

In your bike's case I suspect it's a matter of actual seat tube angle, so a saddle that would allow a more forward position would may be more beneficial. The longer stem then would be handy to preserve cockpit room.

Myself I recently moved to a 5mm longer stem to get the front weighed a bit more (for turns, not uphills) and it actually helped. So small changes can indeed be felt when it comes to setup.
 
#17 ·
Height have some correlation to body size. But it can't be used as the only predictor for proper bar width.

I'm 5'6. Any bar over 740mm wide give me shoulder pain. Also, a bar too high give me numb hand as I would unconciously push the bar away from me. Really low bar height is more kind to my hands.
My mtb bar is 710mm wide, my road bar is 350mm wide.
I'm sure there are plenty of shorter people that can use bar a lot wider than me. But, I don't know what is "normal range", and what isn't anymore without enough statistic numbers.
 
#18 ·
So I decided to revisit the handle bar roll angle. I didn’t remember the bike behaving this badly prior to swapping the bars out to the PNW 31.8’s (I should have mentioned this in my original post but I didn’t think it would make that much of a difference). After looking at my wrists I noticed they wanted to bend down at a hard angle. I loosened the clamps, closed my eyes, and found the most comfortable position. In my case the handlebars are almost perfectly vertical. I gained about 1/4 inch of reach…for a lack of a better term…I guess?

Night and day difference! Much easier to climb and the cockpit is much roomer (no pushing off the back of the saddle). I did get less shoulder pain but I still may trim my bars down to 760. Additionally it also helped with keeping the front end weighted properly on the descent’s. I feel a little foolish but its a live and learn scenario.

I am glad I didn’t jump the gun but again everyone’s input was much appreciated!