You don't have to pedal at unusually low cadences to cause conversion of type IIx (IIb) fibers into IIa. Ordinary training will do it, and in fact most endurance athletes have only 0-5% type IIx (IIb) fibers as a result of this interconversion.
This is in line with what I thought but I wasn't 100% sure so I threw it out there. Thanks for the clarification Andy.