Thread: 6mm of shims
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Old 05-09-2022, 04:44 PM
tjk23 tjk23 is offline
Senior Member
Join Date: Sep 2014
Posts: 513
Originally Posted by ucdcrush View Post
Hi all. Just joined after being a long time reader.

I had a bike fit about 3 weeks ago. He said I didn’t have a structural leg length difference, but was dropping my left hip and not extending my left leg as much. (I think this was causing the right-sided knee pain I was having, which went along with an uneven feeling on my right pedal stroke). We ended up with 6mm of shim under my left cleat, after seeing I was still dropping my left hip with 3mm. He also gave me some pelvic stability exercises to do, stretches, and recommended unilateral leg exercises.

He wasn’t the most talkative guy but did mention that the exercises and the shim may improve things to where the shim could be decreased or eliminated.

So far, though I took last week off, I seem to notice that my pedaling feels smoother when I am concentrating on extending my left leg. But before the shim, and as I was riding soon after getting it, I’d notice that my left stroke felt very smooth and my right very uneven which I chalk up to me sliding over to the left side to protect that leg. (My stroke did feel smoother if I lowered my saddle 5mm, but that felt low to me). For what it's worth, I have a 83.5cm inseam and my saddle height is 73.6. It felt smooth at 73, but also felt too low.

I’m curious from those experienced with shimming, what will I as the rider notice over time if things are improving? Will the pedaling feel smoother? Will I eventually feel like my left leg isn’t extending as far (due to the shim) even with the smooth stroke (i.e., not simply that I’m still dropping my left hip which leads me to feel that lack of smoothness on the right)? And would that be the indicator for when the shim can be decreased/removed?
If you are listing to one side, then your saddle is too high. I would drop the seat and forget the shims. A lowered seat is going to feel too low at first, probably because you have been overextending. Forget all the saddle height formulas and go with what feels right.
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