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Re: Tri Bikes with Greatest Pad Reach/X ?? and the role of Crank Length in modern Tri bike fits [milesthedog]
I'd like to see you put some numbers on some of this.

Of course riders with short(er) cranks position their saddles farther back than those on long(er) cranks, that's necessary just to equalize the rest of the position relative to the pedal, and the x/y axis of the crank. It's *very* clear that many/most riders don't account for this when they first switch to shorter cranks, and it shouldn't surprise anyone that over time this leads to saddles being pushed back in reaction.

How far outside this normalizing standard do you think riders are trending? How do these trends in crank/cockpit length break down relative to rider height/morphology? How have the current generation of top saddles influenced this, and has the actual seated position of the riders changed significantly, or is it largely saddle placement? Saddles like yours and the Gebiomized are definitely going to wind up in a different x/y position than one of the formerly ubiquitous short/split saddle designs for the same normalized position.
If rider seating positions *have* changed, how much of this is due to better saddle designs allowing for increased incidence of and/or a larger degree of anterior pelvic tilt, which would contribute fairly significantly to some of the things you have observed?

In re: gain ratio... it's also possible that at the bike speeds currently common in the pro ranks, increased mechanical efficiency through increased cog size at a given pedal velocity due to changes in gain ratio is a driving force for longer cranks. I would suggest you would want to control for this before assuming biomechanical root causes, especially absent solid data for some of the above...

Just some quick thoughts, interesting stuff!

Tech writer/support on this here site. FIST school instructor and certified bike fitter. Formerly at Diamondback Bikes, LeMond Fitness, FSA, TiCycles, etc.
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Last edited by: fredly: Oct 13, 23 20:08

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  • Post edited by fredly (Dawson Saddle) on Oct 13, 23 20:08