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Removing Rear Sprockets (mod)


King C

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but you could use a chain whip

Chain whips are designed to remove casettes from stock wheels (basicly to stop them from turning). The forse needed to removed a 12t cog of a mod rear is alot more, therefor if you used a chain whip, it would destroy it's self.

I was hping to reuse the sprocket, hence need for removal so thats the second idea out the window.

I don't think there is a way of getting the cog of without damaging it. Even if you use a wooden vice, the teeth rip though the wood and you get no where.

The way i did it was to crush the cog into a metal vice and turn the wheel with alot of forse. Get two people on it if you can't do it yourself. But the cog will be buggerd.

If you just have the hub and it isn't attacthed to the wheel. Take an angle grinder with a cutting disk and carefully cut it twice. Never done this but it is what people do with freewheels when they need to come off.

(Y)

Edited by JT!
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Jt know's it, it's not coming off in one piece. I tried absoutley everything, using wood in a vice to give the teeth something to grip to, simply doesn't work. I tried the wood, and the vice on it's own, by the time you have tightened the vice around the sprocket the teeth are buggered.

I actually brough it into college cos they have nice big vice's and all, got a lecturer to try it, big burly man from 'up tha country' built like a tank, couldn't move it at all, i was in awe that it held even with his strength.

I had considered heating the area, but the cog is steel and I imagine my hub is Alumunium. I just didn't want to start funking around incase I wrecked the entire hub.

In the end I had to grab the angle grinder, fix the wheel somehow, or get someone to hold it steady, pick an area that's nice and clean, and grind away the teeth very slowly towards the hub threads. As you make more and more cuts (really take time to limit damage to the hub thread) you beging to see lines emerge that look like dirt, once you see these, stop grinding that area and move towards the cantre of the hub. I find it easiest to start on the drive side of the hub, make small cuts, and then move towards the non-drive side, doing the same thing untill you see the lines, which are the threads. The bigger the lines become, the more you destroying the hub threads, so try and do this in as small an area as possible, at this point the sprocket will still most likely be firmly stuck to the hub, time to grab a hammer and a screw driver or blunt (masonry) chisel type tool. put it on one of the teeth and whack it hard, the cog should break, making it easier to screw off either by hand, in a vice, or using a dirty old rag.

Clean up the threads and affix new sprocket :)

Best of luck, it's isn't easy, and there's no 'official' way to do it......

If I hadn't lost my phone id have shown you a picture of my old cog, it's a mess. Ill try and get a few pics in the next few days, it will help explain my shitty description!

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They are a right mission to get off, just buy a new one, 12 quid for echo 1.

I know it can be removed but its a task!, get a chain whip and i work mate, put wheel in that, and get a huge pole and put it on end of whip and jump in it.

Cheers

Wilky

Sigh, how many times must it be said, a chain whip will not do the job. Have you ever had to remove a rear cog?

If you fix the wheel to a work mate and attach a big pole and stand on it, the workmate is going to move before the cog does, it wouldn't have nearly enough strength to do it.

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