cog slipping forward and back
 

So I was riding the other day, came to a stop light. When it turned green I tried accelerating only to have the drivetrain slip horribly, i nearly went over the handlebars. Upon back pedaling or skidding, the cog also slips a bit. I have a crappy cyclepro cog on my pro v wheelset. Is the crappy cog the problem? Ive been running it for like 6 months with no problems. Installed by the LBS.

Why would it slip forward? Is my hub stripped? I fear the worst on this one.

The hub is a flip flop. Does anyone know if that limits me to only running a freewheel on the other side or does it not matter and I can run fixed on either side? (In the event the side of the hub ive been using is stripped)

The cog is definitely loose. Remove it and the lockring to see if anything stripped.

tighten cog, tighten lockring. Ride a little bit and then tighten your lockring AGAIN. If the cog continues to slip back and forth it can be bad for the threading and a multitude of other things. Make sure you have the correct tools for this or have a bike shop do it for you. Tightening by hand is not good enough

I had the LBS do it, and after it slipped I brought it to them right away to retighten, slipped again. I think ill invest in a quality cog and lockring (17t, suggestions?) and some tools.

Btw, If you have an 1/8" chainring, can you run a 3/32" chain? I know my chain ring is 1/8", dont know what my chain is, or my cog. Wondering what size I should get the new cog in.

1) remove the cog and lockring; inspect the threads of all three (hub, l.r., cog). you'll know pretty quickly if the threads have been shifting or are stripped.
2) if no stripping has occurred, either take the wheel to a shop to have it installed properly OR install the cog properly by first applying grease to the hub's threads (no need to over do it); using a chain whip to apply adequate pressure; apply grease to the lockring portion of the hub's threads and use a lockring wrench to get it flush with the cog; apply a second push to the chainwhip/cog, and immediately chase that with pressure to the lockring. this should be sufficient; if you cannot tighten the cog (first) or the lockring (second) any further, you're good to go. get out and ride a mile, then re-tighten. this second part is often overkill, but will let you make sure you didn't screw up on part 1.
3) rocking suicide fixed (hub on a freewheel side) isn't adviseable, as the mechanism you use to keep the cog in place when subjected to skids isn't going to be nearly as strong as a reverse threaded lockring.

Sounds like you might have to invest in a new rear hub soon if it continues to slip after tightening.

And. No, you can't use 3/32" chains on 1/8" chainrings or cogs.

one thing you might try is riding it, not backpedaling to slow down and then tightening the lockring

I had a similar problem and my lockring threads were stripped :(

As far as cogs and lockrings go, get the Surly lockring. It has this little lip that fits in with the cog really well. It works perfectly with Surly cogs, but also with Dura Ace cogs. I have Surly lockring and Dura Ace cog, great combination.

Easier and less error prone just to rotafix it. You'll get much more leverage that way anyways.

Dura ace cog and lockring will set you back ~ $35 MSRP USD. There's really absoloutely no reason to skimp on the drivetrain.

Yeah, I made the mistake of buying my Surly lockring and Dura Ace cog at my LBS for like 45, but are you saying that is a skimpy set up or that it is a good one? Is there any better quality cog/lockrings for a reasonable price?

he's saying that it's good. Also, it would wind up being about 45 after shipping, if you bought it online and you wouldn't have the benefit of a shop to take it to if further problems arise.

i was kinda waiting for the OP to say "...lockring?"

Went with a Milwaukee cog/and lockring. Still need to check my hub and make sure its alright...dont have the bike with me right now.

thanks people.

Hey, just so you know, if you are having this problem, be VERY careful. If you are running without brakes and your drivetrain is messed up, you could put yourself in a dangerous situation. For testing purposes, just toodle around the block or something. Don't go down any hills or commute or anything until you have it all figured out. good luck. If you got your wheelset from Ben's then they will take it back if you stripped your lockring threads. They did my replacement on an AlexDH22/ generic hub 4 free99

Really? I can't imagine even the most generous of shops warrantying something like that.

Yeah well I had only used it for like two days before the threads got stripped and I called up Ben's and they said they would replace it for free! I did pay the return shipping (30 bucks), but they even installed my cog and lockring on the new hub for free

EDIT: Buy from Ben's!

buy some loctite red. rotafix your cog w/ loctite to the hub... get a lockring wrench w/ a long handle.. or use vicegrips on the end to extend the handle for more leverage... loctite the ring as well... let the bike sit for 24 hours so the loctite can cure... the cog will never slip. i did this on a suicide hub setup.. and never once slipped my cog ...

This is what I do and I've never had a problem. I use the red kind and then just blast the cog with a heatgun for a minute or two if I ever need to remove it. I've been using a wheelset with stripped lockring threads for 6 months like that and it's still holding up great.

I also have a brake, just in case.

If you're using red loctite (loctite 271) you may want to consider the type of grease you're using. Loctite 271 has an operating range of -65 F to 300 F. Many greases shouldn't be used between 300 to 400 F. If you're heating the cog/hub area to loosen the loctite you may want to repack your hub after you remove the cog.

same thing happened to me.

my hub was stripped, so now the LBS is rebuilding me a wheel with a pretty golden hub :) (but also :( )