I have noticed that when i ride my TT bike i seem to do better with 170’s now that i switched from 172.5
I perceive less strain on my knees and my thigh isnt flexed into my chest. My ST angle is 80 degrees.
Has anyone studied power output as you shorten cranks and steepen seat tube angle?
thanks!
I hope you’ll have others more knowledgeable than I chime in to answer your question. It’s not uncommon at all for people to shorten their cranks when they adopt a steeper position – presumably to keep the hip angle more open which, I believe, is to insure the ability to maintain power output.
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I noticed more power when I switched from 175’s to 170’s and the feel and comfort even up on my arms is much better. There is a technical gearing issue that you will have to deal with and you can find out more about it on sheldon browns website. Just google it and check out the gain ratios.
Triathlete magazine had an article on this a couple months back… and yes the conclussion was smaller crankarms = more (efficent) aero positioning.