For context this bike is fitted with a Continental CDS drive belt, but the belt broken and as far as I can tell Continental stopped producing these belts so I can't get a replacement and they're also not great since the original belt broke pretty fast.
Due to this I'm considering switching it over to a Gates belt system and would like to validate if this is feasible and what parts I'd need for that.
Based on the bike information, I believe the relevant parts for the belt system are:
chainstay length is 462mm
- front sprocket is 39T on a 130m 5 arm pedal
- rear sprocket is 20T on a Shimano Alfine S700 8-Speed, RapidFire Plus
- the original gear ratio is 1.95 and Shimano seems to recommend 2 - 2.25 for that hub
Using the Gates' drive calculator the following setup look like it would be closest to the 462 chainstay length:
55T front, 26T back, 125T belt =>
gear ratio of 2.115 and
chainstay length of 461.96.
Do you think that setup would make sense for this bike? I'm assuming that I can just get the 5 bolt sprocket and fit it on the existing pedal or do you see any issue with that? And to confirm that I'm looking at the right rear sprocket, are the Surefit ones the correct ones to fit on Shimano Alfine hubs?
Also do you think it's worth switching to another belt system for this bike or should I consider a chain drive instead?