I have only two bikes at the moment with rear clusters, one 6 speed and one 5 speed. Everything else is single speed or 3/4 internal gears. However, I'm waiting on a couple of frames to arrive soon that'll be set up with six or seven in the rear (one with a double crank and one with a triple). They'll both be 135mm spacing, so I suppose I could go gear crazy, but I never seem to use more than a couple on my rides.

Neal