[Jeff K.]

Both of them have their pros and cons
Cogged belts can beat chain in lighter weight, and chain can beat it in high torque transfer such as in a really torquey drivetrain. A timing belt is pretty reliable for transferring lots of torque, but there is the chance you could rip it in a worst case scenario, which could be avoided by a good design. Though like Gabe said, you have to get your design down first before ordering belts, because you can't change its length quickly like you can with chain by just popping out a link or two.

If you design it well, it will perform well.

Also, both chain and belts will stretch, so you need someway to tension it. If you just keep it static, then as it stretches, problems will arise of the belt or chain popping off and it failing.

Good luck with your designs though.

Also Lord Britten, what pitch of chain did you use? #25 or #35?