Re:
JayKosta said:
Alex, thanks for the link to the model you created.
It seems to use a 'zero power' value at (or near) TDC and BDC - I would expect an attempt to generate power through the full crank rotation in an 'all out sprint' situation (and doing that would probably produce less cyclic variation).
Jay Kosta
Endwell NY USA
For the purposes of that example (which was to examine what happens to velocity when accelerating), whether power reaches zero or some minimum positive power during a pedal stroke will have pretty much the same effect.
But yes, you are right it's not always zero (indeed it can be negative).
I actually explored a model with a positive minimum torque/power in an earlier item when I examined crank velocity variation during steady state cycling:
http://alex-cycle.blogspot.com.au/2015/01/the-sin-of-crank-velocity.html
In that item I list many examples in the literature and other forms of measurement showing the typical force, torque and power application patterns of two legged riders, or of a single side measurement of two legged riders. The first measurement of pedalling forces was reported in the literature was in 1896!
One thing we can see with all these examples is how power doesn't generally drop all the way to zero while pedalling, and that it is often not symmetrical for left and right legs.
The variance in power/torque/forces between peak and minimum during a pedal stroke is very large, and this is by far the biggest factor impacting on (the relatively small) velocity variations.
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