Certainly a range here, as you'd expect.

I had a number 1 when I was 32 after a greaduated with my Diploma. It was the best haircut I have ever had. No maintainence really, like the others here have intimated with their very short cuts - just brilliant

My hair-length is currently between my shoulder blades, and most of the time I wear it twisted up at the back and held with a shark-tooth comb.
On colder days I wear it "free" or just the front tied back.

It is much more work then short hair and I think this coming summer, as the weather heats up it will go.

The biggest hassle re cycling with long hair is when I timetrial. Hair flapping about in the wind is not aerodynamic, so I have to try and bunch it into a bun that is comfortable but doesn't poke out the back of the helmet...