If you're only doing short distances, like if you're a recreational cyclist out for an hour ride or so, you can get by just fine with a lower cadence in the vicinity of 60 rpm. But if you ever want to go for longer, you will tire your legs too quickly pedaling at that speed. You should gradually try to achieve a good combination of pressure on the pedals and pedal speed that doesn't work your legs as hard (using your gears to achieve it). Generally, for most people, that would be more like 80-100 rpm. I say gradually because it doesn't come naturally. You have to gradually adapt to it. Pedaling faster is easier on your legs, but harder on your cardio-respiratory system. A cadence of about 80 to 100 rpm represents a good balance between the two extremes.
Last edited by Longfemur; 07-02-08 at 08:32 AM.