Originally Posted by Rowan

The difficulty in getting through the 120rpm range has a bit to do with the body's "harmonics" as much as anything else, from what I have read and experienced. It's a bit like a bike getting the speed wobbles.

It's a fine line between being relaxed and maintaining a very level and steady pelvis and not letting the torso move about... in other words, letting your legs do the movement.

You can feel the low-frequency "vibration" in your torso, especially if you have a few layers of adipose tissure going -- it starts moving up and down, but it can't move up and down fast enough in time with your legs. Hence the need to "divorce" the movement from your legs by keeping your pelvis as still as possible.

Riding fixed downhill at high cadence sure is a great way of cultivating the high-speed technique. Oddly, if you can break through that 120rpm mark, to 125 or 130 or higher, the harmonic issue seems to abate rapidly. It's then just a matter of keeping the legs moving without running out of cardiovascular effort.

Optimum cadence varies -- I have ridden long distances with a cadence in the 90s. I probably ride equally long distances these days at 75-80, and it's likely because by fitness is down, and my weight is up. On a recent reasonably flat 300km randonnee, I found my cadence actually increased by 5 to 10 rpm as the event progressed. I find I am more tired after a long ride at lower rpm than when I use higher ones.

If you want some fun, try riding up a hill in a low gear at a moderate cadence, then standing without shifting to a higher gear. See how long you can last at the same bike speed.

A good cadence (80 to 100) is considered to be good for climbing hills, particularly for riders who are (a) new to cycling (b) have dicky knees and/or (c) have heavier loads. Mashing is not a good thing in those cases, and anyone who poo-poos the idea of a triple chainring when there are decent hills around should be ignored, indeed vilified.