In starting my quest in search of a new bike, I'm really trying to understand the fit articles on this site, and I think I get most of it. At least enough to be dangerous. I have one question that I can't reconcile in my mind, though. Looking at this diagram that Dan uses in his fit articles:
This all makes good sense and all, but if your hips are at a 90* angle and your shoulders and elbows are at a 90* angle, then your back can't be flat (parallel to the ground) unless your effective seat tube angle was 90*. To my knowledge, nobody rides at a 90* effective seat tube angle, yet everyone talks about getting a flat back. So which is it? Are people really riding at a ~12* back incline (with a 78* eff seat angle) or are people really riding with a flat back and a hip angle of less than 90*? If the latter, what is the most that you can depart from a true 90* hip angle and not impact power output significantly (or does this vary from person to person)?
This all makes good sense and all, but if your hips are at a 90* angle and your shoulders and elbows are at a 90* angle, then your back can't be flat (parallel to the ground) unless your effective seat tube angle was 90*. To my knowledge, nobody rides at a 90* effective seat tube angle, yet everyone talks about getting a flat back. So which is it? Are people really riding at a ~12* back incline (with a 78* eff seat angle) or are people really riding with a flat back and a hip angle of less than 90*? If the latter, what is the most that you can depart from a true 90* hip angle and not impact power output significantly (or does this vary from person to person)?
Last edited by:
jkatsoudas: May 12, 03 15:43