I built my current bike out of a Nashbar cyclocross frame and fork. Front brake is the Avid BB7. No brake on the rear yet. Rims are disc brake only. Haven't felt compelled to get the rear brake. Commute with a moderately loaded rack. I weigh nearly 200lbs.

I like to ride fast and have to stop and start a lot to get to and from work. Round trip 22 miles, five days a week. Bike is now one year old. One disc brake is serving well.