The belt lineup needs to be very close. Your belt wheels for gates come in 104 BCD and 130 BCD. What mid drive and what IGH do you have. There are only a few IGHs that will hold up with a mid drive and you will need shift sensors in the system. I have found very little on this subject searching on the web. I have a Rohloff with a Gates belt and would love to use a BBSHD but need to find someone who has successfully accomplished this.