Custom Adapters Below are some custom adapter examples: Here is a differential rigged up to receive a motorcycle chain on one side and a bicycle chain on the other. Wired adapter to fix a bicycle cassette onto a standard 3/4″ keyed shaft. Bicycle cassette on 3/4″ shaft. Another view of the bicycle cassette adapter. Adapter for fixing motorcycle disc brake onto a 3/4″ shaft. Adapter for mounting a bicycle derailleur off of a custom frame.