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Old 06-23-2020, 08:40 PM
giordana93 giordana93 is offline
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Join Date: Aug 2007
Posts: 729
I've tried to resist replying because there is so much going on in this post, but can resist no more.

So, you have too much going on and need to isolate some variables. 1st, if you can feel the difference in height between a 33 and 35 or even 38 mm tire, especially when there is lower air pressure in the fatter tires (as should be the case), I'm impressed (but very, very skeptical)--because it works out to less than 1/10 of an inch. That sounds snarky and is not meant to be, only to point out that you may/probably have something else going on. So here are some notes:

do make sure you are reducing air pressure as you go to fatter tires; a 35mm jacked up to even 90 psi will ride like a rock and bounce you off your line and feel unstable

saddle fore/aft certainly feels different/can vary with cleat fore/aft, but there is absolutely nothing that "ties" them together: you push your saddle back or forward and same for the cleats. You will definitely have to adjust saddle height based on moving either saddle or cleat back/forward, but the only thing limiting saddle fore/aft is the seatpost setback and length of your saddle rails.

Same for crank length. It may pull you forward if that's where your weight wants to be when pedaling, but it's not automatic. You can push saddle back or forward or leave it. Now, if you're already at maximum seat height and throw a longer crank on, you will naturally creep forward because you're being pulled closer to the crank centerline, simply because you can't reach that far forward. But drop the saddle height enough and that disappears.

In short, it sounds to me like you're still looking for your best balanced fore/aft saddle + cleat + seat height + crank length position (which can furthermore depend on the sweet spot of your saddle, especially if you like one with more dip/hammock than dead flat). Bottom bracket height and tire width aren't irrelevant, but they are a grain of sand compared to the pea in your princess and pea dilemma (again, no offense, I often use that analogy for folks who are sensitive to minor bike fit changes, including myself)

remember:you have joints at the hip, knee, and ankle. The angles on these will change as you make changes, but you're not a stick man. 5mm forward crank does not make you 5mm taller/more forward automatically; it's a dynamic pedaling motion/weight distribution equation, not simple plus/minus.
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