Wobbly cassette - why?

[richardfm]

I think this is the type of spacer I need.
I've got a 10-speed Shimano 105 CS-5700.

View attachment 707389

That looks like the one

 

[roubaixtuesday]

Go to LBS

Interesting. I have just been to check all my (Shimano) cassettes (part used or new) and none of the lockrings have this skinny washer.
But it's clearly there in the parts diagram.
Given the raison d'etre of the lockring is to err lock to the smallest sprocket, why would you want a washer in there?
Further research (BSS): "The "lockring spacer" (so labelled on Shimano Exploded View diagrams and other technical documents) is a very thin metal washer or shim between the lockrings of higher- end cassettes such as XT, Ultegra, and the like. " So @roubaixtuesday is a high end user, whereas I am not

I've only one bike with Ultegra, and I've seen lockrings many times before buying that.

I am 6'4" though, so "high end" might be literally true

 

[Ajax Bay]

re. the wafer thin washer, IME all cassette locknuts come with that mystery skinny washer. I always assumed it is intended to help prevent the locknut coming loose and deforms under load.

perhaps some locknuts come without?

I've only one bike with Ultegra, and I've seen lockrings many times before buying that.
I am 6'4" though, so "high end" might be literally true

Woohoo! I'm an occasional high-end user. I have found a CS-5700 12t lockring with this skinny washer on (can be taken off but why would you).
The 'washer' is <20 microns thick! For its purpose, read below. It is meant to deform and with a shear caused by 40Nm I'm not surprised it buckles/is lost. [NB has no bearing on the OP's wobbly cassette]
From BSE (edited):
The "lockring spacer" (so labelled on Shimano Exploded View diagrams and other technical documents) is a very thin metal washer on the lockrings of higher end cassettes such as XT, Ultegra. Such a lockring/washer combo is included with a new cassette: the washer is held captive on the lockring and often installed 'unseen'. If you can't see the serrations, the lockring has this washer.
Its utility is to protect the integrity and functionality of the serrations of the alloy lockring (lower tier ones are sensibly made of steel). This thin washer protects the albeit small peaks of those serrations getting worn off by repeated cassette removal and refitting.
There are about 100 teeth in the lockring's serration. Since the thread is ~1mm pitch, each 'click' results in ~10 microns more compression. However the serrations are about 250 microns high which means that with metal spacers between the sprockets of the cassette, the lockring may never tighten enough unless the metal shim is fitted. Plastic spacers are more elastic which allows the lockring to tighten more easily. However with plastic spacers in the cassette they can 'relax' over time which results in a reduced clamping force and can often allow the lockring to go up about another 1/4 turn once the thing has been installed for a while (can cause problems with indexing accuracy 11/12sp).
"So there's some light shed on the very slim shim. Look (closely) for it on your next top-end cassette."

 

[Mazz]

Went to the LBS and told the chap I was after a 1mm spacer for a 10 speed CS-5700 Shimano cassette. He asked me if it was Hyperglide, I said no Idea. Showed him photos of cassette and freehub. He seemed to think the spacer should have notches in it. Anyway, he spills out a tub of random spacers on the counter and rummages. "These are closest I've got, Not sure they'll work but you're welcome to em, good luck, no charge". Thanked him and took em.

Anyway, they're both same inner diameter about 35mm, but one's got a slightly bigger outer diameter. Here's the thing, they're both 2mm not 1mm.

I'll try offering them up to the cassette, although at 2mm I'm not sure the lock ring will thread into the smallest cog very well. Might work, might not.

Stay tuned for another exciting episode of Wobbly Cassette, coming soon...

 

[Ajax Bay]

Likely 1.85mm thick. The lockring does not thread "into the smallest cog", it threads into the freehub (1mm pitch). Try, but carefully check how many turns engage before it goes finger tight.
Without the cassette in place, engage the lockring and see how many turns before it goes finger tight (21/2).
Then put the cassette back on (no spacer) and do the same. If you get 21/2 (which I what I expect) it's bottoming out without securing the sprockets (hence wobbly).
Then put the cassette back on with that 1.85mm spacer and do the same. If you get more than one full turn then fine. Otherwise get a 1mm one.

 

[Mazz]

Likely 1.85mm thick. The lockring does not thread "into the smallest cog", it threads into the freehub (1mm pitch). Try, but carefully check how many turns engage before it goes finger tight.
Without the cassette in place, engage the lockring and see how many turns before it goes finger tight (21/2).
Then put the cassette back on (no spacer) and do the same. If you get 21/2 (which I what I expect) it's bottoming out without securing the sprockets (hence wobbly).
Then put the cassette back on with that 1.85mm spacer and do the same. If you get more than one full turn then fine. Otherwise get a 1mm one.

Cheers for this.
Correct - lock ring screws onto freehub, not the cog, my mistake.
Yes it's 1.85mm most likely..., I was eyeballing with a ruler not a vernier.
Good plan, I'll try this out.

 

[Mazz]

Good plan, I'll try this out.

UPDATE: Tried out your plan...
With cassette removed, lock ring was spun on...3 revs until finger tight.
With cassette fitted (no spacer), lock ring spun on in 3 revs, i.e. bottomed out.

Fitted the spacer and cassette, but there's not enough of the spline exposed for the smallest cog to bite into. i.e. the spacer is too big. I need a 1mm spacer.

Stay tuned for another exciting instalment before Netflix buys the rights to this series...

 

[Ajax Bay]

Could buy a new 10sp cassette which should come with a 1mm spacer. Use that on current cassette and you have a spare ready for when you need it.Edit:
"Most Shimano 10-speed cassettes road cassettes come with a 1mm spacer. It is intended to and should be installed whenever it can fit on the freehub body."
But check obv.

 

[Mazz]

Could buy a new 10sp cassette which should come with a 1mm spacer. Use that on current cassette and you have a spare ready for when you need it.

'kin genius idea👍

 

[fossyant]

Amazon have sets of various width spacers for not much money.

 

[fossyant]

'kin genius idea👍

May not come with a spacer though.

 

[Dogtrousers]

I remember doing some fettling a while ago that involved removing the cassette, or moving it to another wheel or something. Anyway, I found the indexing was a bit off so I re indexed it, and just before I took the bike off the stand and headed off for a cuppa I noticed the spacer lying on the floor. DOH! Cuppa deferred, wheel off, cassette off, spacer on, cassette on, wheel on, gears wonky, gears indexed again.

 

[Mazz]

May not come with a spacer though.

True, I will check before buying 👍

 

[Mazz]

Edit:
"Most Shimano 10-speed cassettes road cassettes come with a 1mm spacer. It is intended to and should be installed whenever it can fit on the freehub body."
But check obv.

Will bear in mind.

 

[ColinJ]

This has just reminded me about my cousin's bike...

I borrowed my cousin's bike on a holiday in Scotland. It felt ok for about 30 minutes but then I noticed that the cassette had come loose. I took it back and he realised that he had left a thin spacer off when fitting the cassette. I think it was a 10-speed Shimano cassette and it needed the spacer fitting before sliding the cassette on. That spacer was thick enough to allow the cassette to be locked in place properly.

There is an interesting article on the subject HERE.

He had a suitable spacer in his box of spares so it was a quick fix. After that the bike was fine for the 200-odd kms that I rode on it.