Without denying that there is benefit in developing the hip flexors, I would like to inquire into the line of thought posed by Andrew Coggan, namely, that efficiency may be optimal in some areas of the pedal revolution, and not as high in others. The ‘holy grail’ of pedalling technique, since long before PCs came on the market, was perfectly distributed torque throughout the pedal revolution. My simple question is: Why?
The study of pedalling efficiency has a lot of factors to it. One factor is whether the angle of force applied is perpendicular to the crank arm at any given point. Anything off perpendicular will involve application of force that does not contribute to the propulsion of the bike. The loss is relatively small at angles that are not far from perpendicular, but can become substantial as the angle increases.
However, there is biomechanical efficiency to consider as well. The discussion about hip flexor usage has focussed upon the weakness of the muscles relative to the weight of the leg and/or driving force that ‘ought’ to be applied to the pedal. But, in the same way as application of force at the pedal can be inefficient depending on the angle of application, there must also be a biomechanical factor to consider. Given the dimensions of femur, tibia and foot; the size (strength) of the relevant muscles; the leverage based on the distance from tendon attachment from joint; there must be optimal loading (pedal driving force) for each point on the pedalling circle; and that force is not likely to be constant.
Assuming this is correct (and, although I don’t have the knowledge to study it in depth, my gut feeling is that it must be correct, because having all the factors cancel each other out is extremely unlikely), my question is whether pedalling efficiency would increase with a pedal-force curve that is not flat, but tuned to biomechanical factors.
Therefore I wonder whether both Frank Day and Andrew Coggan are at opposite points of a spectrum, and the optimum is somewhere in the middle. On the one hand, I doubt that ‘stomping’ is the optimal method, since some smaller muscle groups are underutilised. On the other hand, I doubt that the PowerCrank ideal is optimal, because some of the smaller muscle groups are probably overutilised. (I guess Frank would argue that this overutilisation is a compensatory secret weapon.) This is not to say that PCs are no good; they are probably the best we can do at the moment; but Frank, would you acknowledge that perhaps an improvement is possible over the purely constant-force pedal stroke?
Regardless, it seems to me that a new invention, a ‘PowerPedal’ product, which teaches the body only to apply force perpendicular to the crank arm, would be a useful tool (and maybe more in my price range) which would complement the PowerCranks. But can such a thing be invented? Or has it been already?
