I'm converting my Honda CRM250 to CR125 forks. The axle on the CR is 20mm and the bearings in the wheel of the CRM are 17mm. I was wonder about making a 2 piece axle which is 17mm in diameter with a M14 (M16 I think will be too tight) thread on the end which screws into a 20mm spacer with an internal thread. This spacer is then held in place as normal with the pinch bolts at the bottom of the forks. As I type this it sounds like a terrible idea.
The spacer would be about 40mm long, so I could make it in such a way that would allows the the 17mm axle to seat say 20mm inside the spacer and then M14 thread for the remaining 20mm, which would then mean the axle would bridge both forks at its full diameter of 17mm. The original axle is hollow and on earlier versions of the CRM they came with a 15mm axle, which was upgraded in later bikes for longer lasting wheel bearings.
The other probable easier option would be to fit a 20-17mm split shim into the bottom of the fork.
I can't fit different bearings without machining the hub which is a last resort really.
Go easy on me if this sounds a terrible idea, its why I'm writing this rather than getting on and making it.
The spacer would be about 40mm long, so I could make it in such a way that would allows the the 17mm axle to seat say 20mm inside the spacer and then M14 thread for the remaining 20mm, which would then mean the axle would bridge both forks at its full diameter of 17mm. The original axle is hollow and on earlier versions of the CRM they came with a 15mm axle, which was upgraded in later bikes for longer lasting wheel bearings.
The other probable easier option would be to fit a 20-17mm split shim into the bottom of the fork.
I can't fit different bearings without machining the hub which is a last resort really.
Go easy on me if this sounds a terrible idea, its why I'm writing this rather than getting on and making it.