CG 125 rear sprocket nuts won't turn off - SOLVED

Falco · Traffic Copper Joined: 27 Nov 2015 Karma :

Well I took off my rear wheel today (changing the chain and sprockets ready for a trip on Friday) and (predictably) a problem occurred.
Got the wheel off ok and the first of the 4 nuts holding the sprocket came off fine, but the others won't. They just spin round as does the bolt they are mounted on. Peering into the gap between the back of the sprocket and the wheel there is some sort of nut (or washer maybe?) that is spinning around as well. It is hard to see but it doesn't look like any kind of nut I have seen before and gripping it is proving difficult. I've included an artists rendition of the shape as far as I can tell.

Any ideas on how I can get the bloody things off? I had been hoping for relatively smooth sailing with this bit of maintenance.

Falco · Traffic Copper Joined: 27 Nov 2015 Karma :

Well it turns out that it wasn't so hard as all that after all. The problem was (as usual) with the mechanic.

The answer (found here -[url] https://www.bikechatforums.com/viewtopic.php?t=288342[/url]) is that the bolts and nuts don't hold the socket onto the hub at all, there is a circlip which does that (that was totally gummed to the hub in my case). Going to be interested to find out why one nut came off entirely while the others just span around.

This place is a real font of knowledge. Very Happy

ms51ves3 · Super Spammer Joined: 08 Jun 2007 Karma :

All the bolts have a flat that sit against the thinest groove ever created (that also has a slight taper which makes the problem worse) around the sprocket carrier. As soon as you undo the nut a little bit and you're pushing on that nut, the flat of the bolt moves away from the groove and spins above it so you can't undo the nut any more.

It's a shit design.