Originally Posted by
Brian Ratliff
KOPS is not about fit, it's about weight distribution and body orientation. Fit is about leg extension and hip angle, neither of which are related to KOPS. Where KOPS comes in is in setting saddle setback and handlebar height. For your average built average road racing cyclist, KOPS gives you a rule of thumb that makes for a good tradeoff between handling, power generation, and aerodynamics. It makes for kind of a neutral, flatland road racer position.
Different fits for different uses. For example:
- My sprint track bike has very low bars and the saddle is pretty far forward; my knee is a little forward of my pedal spindle. It means I support more weight on my arms and the front wheel carries more load; this affects the handling, but I want the aerodynamics and the power generation of a closed hip angle.
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- Time trialists are similar except they want their saddles a little further forward to open the hip a bit more. Triathletes are an extreme example because they want the bars low and a very open hip (so they don't fatigue the running muscles), meaning their saddles are even further forward and they have even more weight on the bars.
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- Climbing specialists and recreational cyclists tend to want their weight back and their hips open, so their knees are likely to be behind the pedal spindle.
Thanks Brian. That explanation makes sense but of course KOPS is often set forth as being precisely about fit. The human leg & foot connected to a crank is basically 4 separate moment arms of different lengths acting in a circle - slightly complicated. KOPS has been presented for years like some optimal answer to that mechanical calculus rather than simple body position. I'm interested in optimal leverage etc...the geeky part. Not sure how old you are but when I was racing 25 years ago, we were cutting lawns for entry fees and gas. I couldn't be concerned with esoteric stuff but it's interesting now. I have tried to get all my bikes to have the same position but the hips-relative-to-BB is tougher. Anyway thanks for the thoughts.