I am fortunate to have an accomplished cyclist and trainer teach a spin class I frequent. I can not say if he is correct but..He explains that a higher % of your fast twitch muscles (high power short duration) are employed at low cadences. A higher % of the slow twitch muscles (lower power high endurance) are employeed at higher cadences. The rub is the slow twitch muscles dont really like or know how to go fast and must be trained to do this. He routinely has the class spin much faster then anything I do on the road. Again this is how he explained it. I can say that my comfortable cadence has gone up considerably, I am now not aware of the high cadence.