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I had my chain jump off on my fixed gear when I hit a pothole, and it's gotten completely wedged between the cog and the flange of the hub. I've removed the lockring but can't get a chain whip around the cog to loosen it and the chain is completely wedged tight in there – no amount of force I've been able to generate has budged it at all. Any suggestions for how I might get the cog loose to free the chain?

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  • Quick suggestion - can you get a grip on the chain itself (in a vice if necessary, or by fastening it to something to make it into a chain whip), then use that as you chain whip? – Chris H Feb 28 '15 at 12:07
  • Use a hammer and drift punch against the cog teeth. – Daniel R Hicks Feb 28 '15 at 13:01
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Yeah, I managed to do this one one of my bikes once. There was no way I could brute force the chain from between the cassette and the spokes.

My suggestion would be to use a vice, or do you have one of those Workmate things?

The first thing I'd do is to break the chain and get the whole "wheel and chain" mess away from the frame. It just gives you more room to work. Then, I'd clamp the teeth of the cog in the vice (as I say, I've had good results with my Workmate). Then you undo the lockring, which admittedly can be fiddly. If it has been on a while it will be tight, as you have discovered, and you might need to use a mallet to coax it loose. (I have tried chain whips in the past too, but never even bother nowadays, a vice is far more efficient.)

If you don't have any way of clamping the cog, the only other suggestion is to take the wheel to a shop, who will use their vice to loosen it. With the right tools, it is really only a 30-second job so you may be able to sweettalk them into doing it for free.

Lastly, you should probably spend some time thinking about how this happened. Could be you just got a jump because the chain was loose, but it is probably worth checking your chainline to satisfy yourself that everything is ok.

You might also want to check your spokes for any damage from the chain.....better to replace them now, while you've taken things apart, than have them break later.

  • Thanks! I've gotten the lockring off but yeah, the cog itself is problematic. I don't have a bench or vise of my own so taking it into a shop is probably going to have to be the endgame here. And in answer to your last point, my chain tension was definitely too loose – I'd noticed it the day before and intended to adjust it. And then forgot until my commute the next day when this happened. :( – Scottie Feb 28 '15 at 12:27
  • Haha, yeah these things have a nasty habit of reminding us! If taking it to a shop is an option, do it. You'll be surprised how easy they'll make it look, it's all about having the right tools. – PeteH Feb 28 '15 at 12:31
  • Taking it to a shop is not a bad idea, given that the chain can mess up some of the spokes that way. – Batman Feb 28 '15 at 13:48
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    2 pieces of wood and 2 g clamps would be a good enough vice here, approximating a work mate. – Chris H Feb 28 '15 at 15:08
  • Thanks for the comments and assistance, everyone. I don't have easy access to a workbench or vice and I haven't been able to pry it loose with a screwdriver or anything, looks like taking it to a shop and letting them have a go at it is the best option. On closer inspection it looks like some of the spokes may need replacing (as @PeteH mentioned in his answer) so getting those replaced will be necessary as well. – Scottie Mar 2 '15 at 10:37

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