tekhna

I was shifting going down a hill today when all of a sudden my entire drivetrain seizes up, just locks up. I almost pitched over the front of my bike, managed not to and braked. Get off my bike, look it over, and find that my cassette lockring has come loose, my chain has slipped between two cogs and of course the cranks won't turn. At this point I'm only about 5 miles out on my ride, so I hand tightened my lockring, put my chain on a gear I could spin the whole way home without shifting, and made it back. I'm kinda pissed about this, as my LBS installed it because I don't have a lockring tool. I guess that's one more pre-ride mechanical thing to check.

bdcheung

Oh man, that's pretty bad. I would have a serious word with your LBS - the lockring isn't something you should have to check on a regular basis!

botto 

time to buy one of these

DrPete 

+1. If the lockring is tightened properly for Campy or Shimano cassettes you shouldn't ever have to check it pre-ride. Once it's on there properly it's basically impossible to loosen without the tool botto showed you above.

Do you have pics of this stuck chain? I'm just not understanding what you're describing.

munkyv22

Sounds like the LBS mechanic is teh suck.

tekhna

I don't have a picture, I guess I could loosen it again and do a mock-up! Essentially what happened was the lockring loosened somehow, so the cogs in the cassette all of a sudden had more space than they should have between them, so when I shifted rather than going to the next cog the chain fell in between the two cogs.

mollusk

See the torque spec? I bet that the bike shop wrenches used their "calibrated arms".

botto 

^

i've got one of these, and fwiw i don't worry about torque when i use it:

I_bRAD

I think "good and tight" works out to about 40Nm. I've never had one loosen off anyhow.

DrPete 

Oh, OK, got it. I had somehow envisioned the cassette slipping as a unit and couldn't figure out where the gap was. Thanks for clarifying. Your LBS mechanic still sucks, and if there's justice in the world they should fix it for you. There's absolutely no reason for a lockring to fall off.

aballas

yeah...if that was done properly you'd never have to worry about it loosening....there's teeth that are supposed to prevent it from backing out...and the torque spec you're supposed to put them to is pretty high...

sogood

Yep, inexcusable. 40Nm is very very tight. You need to combine a chainwhip with a lock nut spanner to remove it. Bad, very bad!

Walter

Somebody screwed up big time. Essentially those things should be self-tightening as they tighten in the same direction they rotate as you pedal. What'd he do just finger-tighten it?

The only time I've ever had anything remotely similar happen, in many years of riding, is with Italian thread BBs. That's why some of the old-timers apply Loc-Tite to the threads.

Raise hell, even if you like the shop. Screw-ups like that can get somebody hurt.

xthugmurderx

yeah. that is dumb. i work at a shop and have never "properly torqued" one of those, ever. i wouldn't do it on my bike. i can't imagine the scenario in the shop for that big a ball to be dropped. that's pretty nuts.

dstrong 

So...while we're on the subject...I've got a question about re-installing your lockring. When I take it off I use my chainwhip to stop the cassette from spinning, but when you put the lockring back on, do you need to use the chainwhip or can you just tighten against the locked freewheel? In other words, should you use the chainwhip so that you're not applying all the pressure against the freewheel?

idcruiserman

Use the chain whip.

merlinextraligh

I always believed that,and opined to that effect in a thread on here. However, the consensus in that thread appeared to be that while freewheels self tighten, cassette lockrings don't (hence the need to torque them down tight.) Anyone know who's right?

turbominnow

On shimano lock rings there is a thin washer that is set bewteen the lock ring and the hub. If that washer is not there the lock ring can back out real easliy.

cuda2k

Didn't this happen to 2Roadies (or what ever his name is now) a month or so ago as well? Sounds scary as heck, glad you got stopped before going down.

DrPete 

The lockring of a cassette doesn't have any teeth, so there's no way it can be tightened by pedaling.

Phatman

you're right merlin.

personally though, I've never really seen the need to get on the lockring superhardcore. I tighten it pretty tight, till it clicks a few times, but I would never apply a foot long lever to it to get it to torque. Remember, anything you tighten, you're probably gonna have to loosen again at some point. with that said though, hand-tight is too loose.

DannoXYZ 

Yes, that's correct. The cassette cogs do not spin on the freehub body and thus won't tighten the lockring down. It's the lateral rocking and shaking of the loose cogs against the lockring that vibrates it off over time. Someone at the shop messed up big time.

As for tightening it, you can use a chain-whip if you want. I just roll the wheel up against a wall or door and tighten it down. The spinning motion into the wall lets you build up torque on the lockring.

jccaclimber

I have a way of overtightening things to the point of breaking them an while I've never used a chain whip to tighten a lockring and I've never broken anything inside the free body mechanism.

I_bRAD

No need.

dangerman

yeah, hope you didn't buy him a beer.