Thread: 6mm of shims
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Old 05-13-2022, 05:45 PM
ucdcrush ucdcrush is offline
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Join Date: May 2022
Location: Rancho Cordova, CA
Posts: 6
Originally Posted by benb View Post
6mm seems huge for a non-structural discrepancy.

How did this guy decide you had that big of a discrepancy anyway, and how did he decide you have a functional and not structural one? Chances are anything he was able to do in a bike shop/fit-lab can't possibly be accurate.
He watched me pedaling under load from all sides, and saw that I was dropping my left hip. Tried 3mm, still dropping left hip, added another 3mm. I didn't explicitly ask him whether at 6mm I now wasn't dropping my hip, I just know he decided to stop at 6mm and told me to go ride on that for a while and let him know how it was. He also pulled my shoes off a few times to adjust cleat location and rotation.

He did a physical exam. I don't think he was claiming that he knew my legs were identical length. Just that no physical difference jumped out at him when I was laying on the table. Maybe for some people he can quickly see that their legs are actually of different lengths. And probably no one has perfectly symmetrical leg, but I'm guessing a difference that isn't noticeable probably won't be something making or breaking a bike fit.

As I mentioned above, given that way I favor my left side (with the titanium nail in my hip), I am not surprised that I pedal differently on that side. I've also heard that we tend to "protect" our dominant side, which in that case is my left side as well. Also, I've tried to self-fit for quite a while now, while not doing any flexibility or strength work off the bike. I'm hoping with the shim and all the stretching and unilateral leg work I'm doing now, that I'll see an improvement.

I started the thread though to ask others who have used shims, what experience they had to know that they could try decreasing or removing the shim. I'm still wondering about that. But I believe one thing could be that I am able to ride at the saddle height he put me at while feeling that my right leg (where I've had knee issues) is nice and smooth. That's assuming that the un-smoothness I've experienced there is because I'm dropping my left side down. So could be that once I have a nice smooth right side stroke, I can take one of the 3mm shims out and get my left leg used to extending that extra bit to where I'm not dropping it and messing up the right side stroke.
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