Bumping this up because I found this thread looking for belt replacement options for the normal Ride1Up Roadster (non-gravel, TopTrans belt) and couldn't find much written on it. I ended up going with a Gates CDN 118T belt, which is the closest match to the stock belt.
Specs:
Stock: Top Trans Belt - 11M-1287mm x 12mm (117 teeth by my count)
Gates: 11M-118T-12CTS 1298mm
Gates Carbon Drive CDN belt, 118T
www.gatescarbondrive.com
Gates also makes higher performance/durability versions that cost more. The CDN is about $50. You can order from various online bike retailers or probably your local bike shop.
- CDX: High performance commuting, trekking, mountain & cargo bikes & eBikes, and extreme conditions
- CDC: City commuting, mid-motor eBikes (50Nm or less)
- CDN: Hub-motor eBikes
- ST: Recreational riding (3 speeds or less)
At the same price as a stock replacement from Ride1Up, I think switching to the Gates is a no brainer as they have a much better reputation for durability. Definitely worth a try for the few people I've seen mention breaking multiple belts (even upgrade to the Gates CDX belt).
My stock belt didn't actually snap, by the way. Instead, the teeth were starting to rip off the belt, causing increasingly more and more skipping, regardless of belt tension. It was not obvious this was happening until I actually removed the old belt and examined it closely. Something to watch out for.