In use the cranks move in and out of phase with each other by about 15 degrees as each crank arm is hurried through the dead center parts of their travel. There is a lot of anecdotal evidence accumulating about the benefits of Rotor cranks, and some web discussions have claimed that they have little or no adaptation time, but we'll have to see what we discover about them.

Carl raised the possibility of setting up two otherwise identical bikes on exercise stands with Power Tap wheels to compare them scientifically, then he thought better of it because that's a lot of effort to go to and we're not that scientific a group to begin with.

This subject slid into a discussion of other non-standard crank designs (Biopace rings, Power Cam cranks, etc.) and people's experiences with them. Dave Siskind feels that most of them are likely to work best for low cadence mashers and to give little or no benefit for high cadence, more nearly circular spinners. Even with his shorter cranks and higher spin rate Mark still seems to be a fan of Biopace rings and wishes the Rotor did not have proprietary bolt arrangements that would prevent trying Biopace rings on a Rotor.

Marks comments; I don't believe they speed you up through the dead center parts of the circle. They just go faster up than down. I imagine a plot of the effective gain ratios would be a long, shallow sine curve. The result is that when one leg reaches full extension, the other is already 15 degrees past TDC. There have been dozens of oddball crank systems over the past 120 years. None have proven effective, and many people lump the Rotor with the rest. However, this is the 1st one where I can't spot the flaw, if there is one besides price and weight. They add about a pound, which is only half a % of the typical rider/bike. Most of the parts seem to move only slightly and slowly relative to one another, so friction probably isn't a huge factor. If the UCI bans them, then we'll know they work.

As for BioPace - If Santa leaves a Rotor crank under my tree, (preferably 150mm, if he's listening) I'll find some way to install properly lumpy rings on them. I just installed a 110mm BCD Biopace on a crank with obsolete 140mm and 86mm bolt circles.

Or, it may be enough to orient the cranks so that the highest gear ratio comes later in the pedal stroke on a 'bent.