To change the drive belt is not a job you would contemplate at the side of the road. The rear wheel needs to come out and then the swing arm, as the belt loops around the swing arm, and to get to the swing arm it is seats and lower rear bulkhead out. Having said that I am not aware of a drive belt having failed or been changed and there are plenty of M3W's I regularly drive with who have done 30,000 plus miles on the original belt.
