A small introduction of myself before writing this item: I have been training exclusively on powercranks for one year now and they have proved to be very beneficial in tilting both my running and cycling performance to another level. I ended up as my age group champion in Kona in 2011 and took off 40 minutes from my 2009 Kona time. But that's another story ;-)
This year I started to experiment with short (135mm) powercranks, which is 40mm shorter than what I was used to. "Why?" would most people argue. It was Frank from powercranks that got me interested in the idea because he assumed that shorter cranks (combined with higher seat and lower front) would put you much more aerodynamically on the bike and saving lots of watts on the bike. This was a plausible assumption that had yet to be proven with windtunnel testing and so on. Anyway, since a few months I ride these ridiculously short (although Frank still thinks they are too long) cranks. And I like them! At first I thought I would have to change gearing or pedal a much higher cadence to attain the same power output because of the smaller leverage of those cranks. This is not true: for some reason I manage to generate the same power output with the same gearing and almost the same cadence. I think the reason for this is the more efficient angles of your joints when the cranks are in the best position to generate power which is in the upper quarter of the pedal movement.
So I was quite confident that riding short cranks wouldn't affect my bike performance (from a biomechanical point of view) too much. If there really were aerodynamic benefits I expected to gain some extra speed from going short.
This weekend was the first real life test during a long distance duathlon in France. The bikeleg was 85km long on a rolling course and there was a terrible wind and part of the course was a quite heavy traffic area. Despite all this I manged an average speed of 38.5 km/h which was much faster than I'd anticipated at this early stage in the season and this gives me confidence that going short really might have some real benefits! Next real life test is scheduled on June 10th at Eagleman 70.3. To be continued!