I have a crabon fibre bike. Then I put a B-17 N saddle on it. I will occasionally commute on it (now that I have a Carradice Barley, I can throw it on the night before and can take a change of clothes with me). but not very often. I use it mainly for group rides.

It's pretty bare bones...two bottle cages, a pump and small saddle bag. Of course, I took off the reflectors to save weight.