My version of the frame has a replaceable rear derailleur hanger. The dropout on the opposite side of the frame isn't replaceable. In the bike's most common configuration, I use Nashbar's carbon fiber cyclocross fork, which allows me to use an Avid BB7 Road disc brake. The CX fork quickens steering a bit, which some might not like. If I could find a cantilever brake that I didn't hate, I'd be tempted to go back to the aluminum fork that came with the frame...