After my not so fun and expensive experience with the previous bike and #25 chain, I decided to use #35 chain for the rear wheel. Since I am using a wheel with a coaster brake, I had the following options:
- No. 25 chain
- 8mm d-shaft sprockets are readily available
- 60/66 tooth sprockets are also available
- I would need to have an adaptor for the coaster brake wheel made, or, switch to a wheel made for a gear set and buy an adapter
- Cost: $20 for 60t sprocket, $10 for 15 tooth sprocket, $30 for chain = $60 + adapter to bike wheel (or +$15 for an adapter to a standard rear wheel, plus the cost and time of locating a 20″ wheel with a hub for derailleur gears)
- No. 35 chain
- Need to adapt a motor sprocket from 3/8″ or whatever to 8mm
- 60t sprockets are available
- Would still need to have an adapter made for the wheel
- Cost: $8 9t sprocket + $20 60t sprocket + $6 chain = $34 + adapter to rear wheel + adapter to 8mm d shaft
McMaster-Carr has unfinished sprockets available. These have a small bore hole that can be drilled out to the size you need. You need a flat one for the 60t and one with a hub for the 9t. Adapting these should be fairly straightforward as the bores just need to be drilled out to the right size.