Originally Posted by
tomato coupe
What Mark has done is what is commonly known as a “back of the envelope” calculation, (snip)
Max power output 1000 W (pretty average cyclist)
(snip)
In addition, I’m also going to take exception to using a 140 mm lever arm when calculating the torque on the bottom bracket. I think the effective lever arm is closer to 220 mm.
(snip)
Conclusion:
Clearly Mark’s model, when fed with proper initial assumptions proves that the effect of frame stiffness on efficiency is significant. WRONG! The results differ by a factor of 10, but they both fall into the gray area that warrants no solid conclusion. A more detailed calculation or careful measurements are still required to resolve the issue.
Cheers
Thanks for this, I think that's a pretty good summary.
I think there might be a few cyclists out there with a max power of 1kW who aren't happy with being classified as "pretty average". Some of us don't have fast twitch muscle fibres.
The 140mm lever arm to the pedal was the part I was least happy with, it's simply what I measured as a typical lateral distance. How did you come up with 220mm?