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Discussion Starter · #1 ·
I'm installing a new cassette and I noticed when installing the new one that there is a thin, flat, metal ring that threads onto the lockring between it (the lockring) and the first cog. This ring covers the "teeth" on the lockring so that they won't engage with the teeth on the first cog. Is this ring necessary?

The reason I ask is because there wasn't a similar ring on the old cassette that I removed. The new cassette is a Shimano Ultegra 6500 and the old was a Sram PG-950.

Thanks and forgive me if this is a stupid question.
pcm
 

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Every little counts...
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Don't let it bother you. Tighten the lock ring up to torque (50 Nm?)...a good hard yank and it won't come off.
 

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Discussion Starter · #3 ·
OK, I determined from Shimano's website that the ring I was referring to is called a lock ring spacer and from the exploded view diagram on Shimano's tech site, the ring is necessary.

The lock ring says to tighten to 40 Nm. I borrowed a torque wrench from a co-worker and started to tighten it. My question now is this (and I realize in advance that this will be tough to answer): how tight is 40 Nm?

I ask because it seemed like I was really bearing down on the torque wrench and it didn't appear to reach a point where the wrench started to "click" because it was at the proper tightness. I don't want to tighten too much and strip the threads however I don't want it to be so loose that it comes off when I'm 30 miles from home either.

Thanks
pcm
 

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NeoRetroGrouch
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6,491 Posts
PCM said:
OK, I determined from Shimano's website that the ring I was referring to is called a lock ring spacer and from the exploded view diagram on Shimano's tech site, the ring is necessary.

The lock ring says to tighten to 40 Nm. I borrowed a torque wrench from a co-worker and started to tighten it. My question now is this (and I realize in advance that this will be tough to answer): how tight is 40 Nm?

I ask because it seemed like I was really bearing down on the torque wrench and it didn't appear to reach a point where the wrench started to "click" because it was at the proper tightness. I don't want to tighten too much and strip the threads however I don't want it to be so loose that it comes off when I'm 30 miles from home either.

Thanks
pcm
40 Nm is about 30 Foot-Pounds. Press down with about 30 pounds on a 1 foot long wrench or 60 pounds on a 6 inch wrench.

Also, there is no force on a normal set up that is trying to back off a cassette. I wouldn't worry too much. - TF
 

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Call me a Fred
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I've never worried about under tightening a cassette. It can't fall off the bike. I've never had one loosen, they seem to self-tighten if anything.
 

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LOOK lover
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I recently had one come loose on me - it was a few days after I switched cassettes. After hitting a pothole (arghh) I noticed a 'buzzing' noise whenever I hit rough pavement. All I could tell it was coming from somewhere in the back - I thought maybe my hub had a problem. But then I took the wheel off to check it out and felt the movement on the lock ring when I touched it. Used a minitool and a tire lever to cinch it back down and was on my way.

Anyway, there is nothing acting on them to back them off, but likewise there is no force that serves to 'self tighten' them. Cinch it down pretty good and listen for any 'buzz' afterwards. They would have to unscrew quite a bit before disengaging - I would think you'd notice long before this happened, so it's not like you need to worry about your cassette disassembling mid-ride.
 
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