Bicycle Mechanics - rear cog stripping....?

so i recently converted my bike to a fixie, and got a brand new wheel for it, has less than 10 hours or so riding and the rear cog is already starting to strip? can anyone give me some advice on what to do to prevent further damage, and once stripped is it too late to do anything about it?, also, advice on how to avoid this in the future would be great, thanks,
-ryan,
funkstamari@yahoo.com

When you say the cog is stripping, do you mean that it is coming loose, or that there are exposed stripped threads? Are you running a proper track hub with reverse-threaded lockring, or a freewheel hub with standard B.B. lockring?

Even if you have a track or flip/flop, there are different threading standards and you need to make sure your hub and cog match.

Even if you have a track or flip/flop, there are different threading standards and you need to make sure your hub and cog match.


I agree. It is possible to have a proper match and strip the threads. Poor quality will do it. I've seen it once or twice. Your cog should thread on easily, not sloppily or loosely.

I'd pull the wheel, take the lockring off, rotafix the cog on, reinstall the lockring (using a good spanner, like the Hozan), and see where that gets you.

Even if you have a track or flip/flop, there are different threading standards and you need to make sure your hub and cog match.

i think you're referring to lockring threading. unless he dug up something ancient, using the wrong thread cog is unlikely.


can anyone give me some advice on what to do to prevent further damage, and once stripped is it too late to do anything about it?, also, advice on how to avoid this in the future would be great, thanks

ryan, about the only thing you can do is try to tighten the cog down, it'll either hold or it won't. if it does, make sure the cog and lockring are TIGHT. i brace the wheel, with inflated tire on, against something solid and lean into the chainwhip with all my weight (~160 lbs, YMMV) to lock the cog down; i do down similarly to the lockring with a set of lockring pliers, which work better than a spanner.

some hubs and cogs are simply prone to stripping, no matter how they're installed. avoid quando and sovos hubs, at least the older ones; the threads are soft. cheapie cogs like cyclo also should be avoided, they are thin and therefore don't distribute load well, and can wreck any hub.

I stripped the hub on my first track bike in 1965 - French-threaded hub, BSA sprocket. The seen-it-all local bike mechanic wrapped the stripped threads in aluminum foil. Amazingly, the repair worked. I don't remember whether I replaced the wheel at some point before selling the frame three years later.