Bad bike fit based on what muscles are failing during a workout?

So I built up a new-to-me frame (2014 Madone) last week and have been trying to replicate the fit from my previous frame (2009 Fuji Team Carbon) and I think I’ve gotten it close. Saddle height, setback behind the BB, nose to center of bars… all are matching measurements. BUT doing Charing last night, my glutes and hamstrings were the first to fatigue toward the end of each seated sprint. I expected my quads to burn during a workout with intentional sprints but I was never really able to transfer power to quads once I started fading.

Does the failing rear posterior chain mean that my fit is off (fore/aft seat postition)? Or just that I was digging deep while seated?

Charing 10/30/19

I already know part of the answer is “get a professional bike fit”. :slight_smile: It’s on the list, I promise.

Have you done Charing before on your old bike? If not, throw your old bike on the trainer and see what happens.

As for your new-to-you bike:

Same saddle?

Same crank length?

Same pedals and cleat position?

P.S. nice work on Charing. Those are some big watts.


Adding to the double check:

  1. Same bar drop from saddle?

  2. Same bar reach and hood reach?

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I didn’t really get into TR until lately, but did the Short Power Build Low vol on the old bike in Aug/Sept. I just don’t remember my glutes/hamstrings feeling like this.

As for the new bike parts. I moved my R7000 full group to the new frame, but I’m using a different saddle because the one I really like is on my CX bike for now. That’s another reason I’m waiting for a real fitting, I’m not settled on what parts will stay on the Madone just yet.

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The bar drop is the same and it’s the same bars/shifters from the old bike. The saddle to bars are actually just under 1cm shorter on the new bike, so I thought, if anything, that would relax my position a bit and put more focus ONTO my quads.

Maybe the answers are: 1- get a fit, 2- do more sprint workouts.

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The difference seems minor, and not as likely to lead to changes in muscle loading like you describe. Worth thinking about, but you may just be experiencing general training effects that will improve with more work.

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Thanks for talking through it with me. I’m going to leave everything as-is for now to see if it’s “an issue” or just working certain muscles harder during specific workouts.

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had something weird happen to me last week. A couple weeks ago I replaced my saddle (same model) and realized how worn out the (minimal) padding was on the old saddle. Rode for a week or two, it felt a little different but seemed ok. Then on Friday outside ride last week my right foot cramped about 90 minutes into a 2 hour tempo interval. On Sunday at the gym I realized my right glute was frozen and I couldn’t do single-leg Romanian deadlift on the right foot. Talked to my fitter and he suggested lowering seat 2-3mm (and/or slightly move forward), did that and last night it felt so much better.


Yes, saddles are finicky.

I really liked my titanium railed Specialized Phenom. I ended up getting chromo railed versions for the tandem and the trainer. While similar, they aren’t quite the same and required a bit of tweaking.

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