I just had a fit done about a month ago and everything is feeling good. The fitter suggested that as I got more flexible, I could lower my bar and be more aero. I ride a Trek 2300 road bike fitted with Profile Carbon Strike bars. The bike came with 4 shims under the stem. I’m thinking about moving them one at a time from under the stem to on top of it. I think that would work out OK. Seems like I’d need to move my seat a tad forward to keep the same angle between my torso and upper leg. My seat is currently all the way back on the rails. Anybody have any thoughts/advice? The fitter is a 3 hour drive away, and I can’t easily run there to see him. Thanks for any input!
Dirtroads,
Ever hear of a thing called the telephone? Invented by Alexander Graham Bell. Predates the computer and internet.
If you trusted the fitter, call him up and ask him.
In actuality, your shims should not total more than 1.5 times the diameter of your steerer tube. 1.125" x 1.5 = 1.6875". Converting to millimeters 1.6875" x 25.4 mm/in = 42.8625 mm or about 4.3 cm. A cm is slightly less than 1/2 in.
Lowering your stem one shim should be such a small change that no other change should be necessary. Usually, all the shims will not be uniform in width. This should allow you to make even smaller adjustments as you go, by moving the narrowest shim first. Then moving a wider shim on top of the stem while moving the first shim back below the stem, etc.
Effectively, you are causing your torso to rotate towards your feet, the point of rotation being a point in your spine at about your hip girdle. You do not want to rotate your pelvis. If you do this, you will begin to place more pressure on your “tenderest parts” which you do not want to do. Ultimately, if you move all your shims, you should not be dropping your position at your bars more that about 1.7 inches at most. What you should desire to do is keep your reach the same (distance from saddle tip to bar). Depending on whether your stem rises, is neutral or drops could change your reach very slightly after you move all your shims. You would then have to consider changing your stem to a shorter one, but stem length changes in one centimeter increments. A one centimeter change in stem length will probably exceed the change in reach by more than half. What this means is that you will be better off not changing your stem length.
If after you make these changes in your stack heigth, you feel uncomfortable or it just doesn’t feel right, you would be better off to return it to how it was before and leave it alone.
Your question about moving your seat to compensate for the stack height change could be done to keep your reach the same. Remember though, that as you move your seat forward after dropping your bar, if you shorten your reach, you will effectively cause your back to begin to arch to accommodate this shorter reach. This arching will negate your effort to get aero by dropping your stem. You should not be trying to keep the angle between you leg and your torso the same. You should be trying to narrow this angle slightly by taking advantage of your "increased " flexibility to drop your torso to become more aero. If you try to maintain that angle, you will only rotate your entire body around the bottom bracket (which you do not want to do). This will not lower your back (height from ground to highest point on your back). This then will not reduce your frontal area and will not make you more aero.
Are you sufficiently confused now? Hope this helped. FWIW
What Ben said (seriously).
Good post, Ben.
I have the same bike and bars you do and want to lower my bars also. Is taking the spacers out an easy thing to do? I have very little experience working on my own bike.
Sure, I’ve heard of the telephone, the computer and the internet as well. I’ve also heard of and learned that sometimes there is value in more than one opinion, especially if it comes from an independent source that won’t necessarily profit from selling me a new stem or something to keep my fit “perfect”. I also realize that you usually get what you pay for and will keep that in mind. After the lecture, I appreciate the time you took to post an answer. I was hoping some experienced rider could share their experience with someone who is trying to learn a bit about the sport. I’ll leave the saddle “as-is”. I’m sure I move around on it by at least the amount that the bars will move by lowering them. Thanks!
I think you’re correct about moving the saddle a little forward to keep the same hip angle when lowering the stem.
I disagree with Wants2rideFast on a couple of points.
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Rotating forward is necessary even if it puts pressure on your “tenderest parts”. That’s what tri saddles with extra padding on the nose are for.
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Rotating forward will make you more aero. Your back will be flatter and you’ll have less frontal area exposed to the wind.
Wants2rideFast seems like a “Slam” guy; I’m more of a “FIST” guy.
My advice - make some changes yourself and see how it feels.
One other thing: you might want to angle the nose of the saddle down just a hair when you lower the stem.
I appreciate the time you took to post an answer. I was hoping some experienced rider could share their experience with someone who is trying to learn a bit about the sport.
Dirtroads,
Always remember that sometimes when you wish for something, you may just get more than you really wanted.
Now you have two totally opposite opinions about what you should do. Now you’re going to have to make up you own mind or conduct a bigger poll.