Not sure, it's a Sturmey Archer type rear hub so I'm guessing that I'll need to replace/rebuild the whole thing. It has SA stamped on it and also 'AW' but it is single speed obviously, I'll post a pic when I have time. It's kinda weird to be honest, it has tabs that line up with slots in the wheel and a large circlip secures it in place. It sounds like a shopping bike freewheel but it slips and locks up every now and then so it needs sorting.
