Wobbly Cassette

[chris1969]

Hi

The rear wheel on my racing bike has a Shimano 8 speed cassette with 25/12 teeth (largest/smallest sprockets). The two outer sprockets are separate from the rest of the cassette which I think is standard on this sort of cassette. The freehub measures about 35/36mm from where it enters the wheel to the end of the ribs which run along its length.

I recently removed the cassette and reinstalled it. When I tightened the lockring I noticed that the outer sprockets had a few millimetres room to move from side to side. I also have a hybrid bike with an 8 speed cassette and so I put that onto the racer where it fitted nice and snugly. I put the two cassettes side by side and the hybrid is about 2mm longer from outer to inner sprocket.

So my question is why is there room for the sprockets on the 25/12 cassettes to wobble from side to side. And why does the other cassette fit snugly. I can think of a couple of explanations:

1) The shop fitted the wrong cassette. Possible but my understanding is that a 35mm hub is standard size for an 8 speed.
2) I mislaid a part, perhaps a spacer, when I removed the cassette?

I’d be really grateful for thoughts/ideas here. I’m finding it a bit of a headscratcher 

Thanks

Chris

[Brucey]

if you look at the lockring there should be a model number on it. If you type the model number and a few words into a search engine you can find out how it is meant to be put together, if it is a shimano cassette, eg "CS-50-8 EV techdoc" soon gets you
http://cycle.shimano.com/media/techdocs/content/cycle/EV/bikecomponents/CS/EV-CS-HG50-8-3072A_v1_m56577569830818508.pdf

if the 7th sprocket is loose this can mean

a) there is a missing spacer
b) that the #8 sprocket has been fitted wrongly
c) there is some fundamental problem (eg. wrong cassette, wrong freehub body)

I would say that b) is quite likely if only the #7 sprocket is very loose; the spline is 'timed' so that it will only go on one way; the other seven sprockets obviously don't go onto the freehub body if the spline is set wrongly. However the #8 sprocket will look like it is fitting (but isn't, actually) even when the spline is set wrongly. So it is a very good idea to double-check that this is set correctly.

hth

cheers

[chris1969]

Thanks Brucey

It seems most likely that I've mislaid the spacer or (possibly) that the LBS didn't fit it in the first place. Interestingly there was a development after my original post. I had ordered another 8 speed cassette for my 'store' which arrived yesterday. I fitted this onto my bike and it was nice and snug without any spacer.

This new cassette was shimano 8 speed and was labelled as a Shimano on both the lock-ring and and one of the sprockets. I went back to the original and it was labelled as Shimano on the lockring but not the cassette. So it looks like the LBS might have spliced together a non-Shimano cassette with a lockring and (possibly) included a spacer which I then lost.

So it looks like problem solved. Thank you.

Chris

[albal1]

Looking at similar problem myself. 'Wobbly cassette'. When fitted 10 speed campagnolo cassette. Fits ok with lock ring tight and all cogs tight, yet the whole cassette has a few mm of play on the freehub. Now the wheel was bought 2nd hand, Khamsin assymetric. Looked like new when I put it on.

So this gets me thinking it is a freehub issue. With the cassette off, there is a small amount of play, accentuated when cassette fitted.

I've no reason to believe incorrect freehub.

Are the pawls+ spring to blame?

Bearings worn out? (On freehub)

No spacer required on 10 speeds, tried it with couldn't get lock ring on.

Will try a different cassette see if that helps.

[Brucey]

if a campag freewheel body is loose it means

a) the locknuts are not tight on the axle
b) the bearings that support the freewheel body are worn/badly fitting
c) the freewheel body is split lengthwise.

cheers

[albal1]

Thanks brucey, going by that it looks like worn internal bearings. I've never removed them before. It looks technical , trying to avoid spending £60 on a replacement freehub on low end wheels.

[NetworkMan]

Another possibility with Shimano is the lockring. There are at least two types with the one intended for an 11T 8 speed top sprocket having more thread than the other which came from an old 13-30 7 speed.. I got caught out with this when building a hybrid cassette because the thread fully engaged before it was completely tight.

[peetee]

If the outer two sprockets are able to move in and out then the others should be able to do so as well. If they don't perhaps the problem is witness marks on an alloy freehub body that are preventing the sprockets sliding up the body and seating correctly. Another thought is that what you are seeing is the variable profile of the teeth which, when viewed from the back of the bike, makes the sprocket look like it is oscillating.

[Halla]

Hello All.

Recently, during an after ride clean, I found the cassette to be rather wobbly. It is a 7 speed RSX, so pretty old, but not huge mileage.

After some internet searches I decided on complete disassembly.

I found the swaged head of the 10mm bolt to be partially sheared off the main bolt. a new bolt has been ordered at the LBS for £3

This is probably caused by heavy handed assembly at some point.

I had at one point suspected the cassette to be cheaply made and therefore loose on the freehub, time will tell after reassembly.

Has anyone found damage to this bolt to be a common problem?

[Brucey]

I've seen about half a dozen bolts like that where the head gave up holding anything. I suspect that they have varied the manufacturing method slightly, and some are stronger than others. Some seem to be upset from a piece of tube in such a way that there is very little thickening where the head is.

If I am tightening a bolt I don't much like the look of, I often use a twelve point bit and fit it to the bolt such that the head of the bolt sits over the shank of the tool (where there are no splines and the diameter is larger); I think this helps support the head and stops it from collapsing inwards. Often if the tool doesn't come out of the bolt easily, which means you were sailing a bit close to the wind.

FWIW it is not unusual for freehub bolts to need a fraction of a turn to tighten them; what happens is that the freehub body settles a little where it bears against the hubshell. This is perhap more likely on 'road' hubs Unlike MTB ones), since they don't usually have a backing washer between the hubshell and freehub body.

New bolt should have you sorted out OK. Not a bad idea to clean the interface between the freehub body and hubshell; there can be all kinds of grot in the joint if it has been moving around.

cheers

[Halla]

Thanks Brucey

I gave it all a good clean this afternoon.

I was not sure about the large washer which had attached itself to the hub. There was some dirt in the area around the washer. I will give it all another clean before reassembly.

I always hope that all this information helps someone else along the way.

Regards Andy

[offroader]

The bolt shoulder failure is quite common

There's at least two different styles

The one pictured has a kind of built up ball that looks quite solid. Nevertheless the load bearing surface failed with approx half cracking off 18 months ago after 18 years. The photo isn't the best, DSLR was half inched in house burglary, but you can roughly see that the flange isn't equal thickness

It's replacement failed yesterday coincidentally. It was of the second type which looks like the tube has simply been flared to form the shoulder. It doesn't actually look damaged but it came loose twice which tells me something is wrong. I guess the taper is no longer flared as it should be.
No photo as it's gone back into a donor wheel until a new replacement arrives