cassette play

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22camels
Posts: 302
Joined: 21 Sep 2013, 8:15pm

cassette play

Post by 22camels »

Sorry if this has been asked a million times before.

I changed my cassette+chain for the first time the other day.

Having taken off the old cassette, I put on the new cassette (an 11-34 9-speed Shimano HG50 MTB) - which came with the inner 6 cogs in one piece, and the 3 smaller ones I had to put on individually, with one spacer, I made sure the grooves were aligned with those on the freehub, hand tightened the new lockring, and tightened it about 180 degree more with the wrench, I didn't want it too tight cos I carry an NBT2 portable cassette removal tool for emergencies which requires the cassette not to be screwed on super tight.

Then I checked for play. There was no play in the plane parallel to the cogs (the plane of the wheel), but I did notice a little play in the direction perpendicular to that - i.e. if I twisted the cassette side to side holding the wheel still. I first thought it was bearing play (I thought I'd perhaps adjusted one of the hub locknuts by mistake when unscrewing the old cassette) but no - it was definitely none of that cos when I put the wheel back on and secured the QR, there was no play in the wheel. Then I thought it was something to do with the new cassette (which was slightly different to the old one, an 11-34 vs 11-32) or that I had put the cogs on incorrectly. I redid it all, no change. I put the old cassette back on, and it was the same too.

i) is it supposed to be like that?
ii) is it because I hadn't fully tightened the cassette lockring to the recommended torque and would go away if I had (I tried comparing the play when it was just hand tight vs another 180 degree of wrench-tight and it appeared to make little difference).
iii) it appears to work fine - gears change smoothly, no rubbing. Is it still worth getting it checked out? I am going on a week's tour soon and don't want it to become an issue.

Thanks!
pwa
Posts: 17371
Joined: 2 Oct 2011, 8:55pm

Re: cassette play

Post by pwa »

Have you made sure the freehub body (the bit the cassette slides onto) is properly screwed onto the rest of the hub? It is tightened (or, at least, mine are) by a large allen key inserted where the axle goes. And you are right to avoid overtightening anything.
22camels
Posts: 302
Joined: 21 Sep 2013, 8:15pm

Re: cassette play

Post by 22camels »

don't remember seeing any allen key bolts on the free hub - just the locknut. but maybe i should look again. but i didn't get the feeling that the freehub by itself was loose. It was the cassette mounted on the free hub which had a bit of play when twisted.. i.e. hold opposite ends of a diameter of the big cog with fingers, and try to move them in opposite directions - one towards the wheel, one away - I could feel it wasn't fixed solid on the freehub - a degree's play perhaps.
Brucey
Posts: 44521
Joined: 4 Jan 2012, 6:25pm

Re: cassette play

Post by Brucey »

you don't say what hub you have but I'm guessing it is a shimano cassette hub.

There is a torque value on the lockring which you should follow, else risk that the sprockets will move around and wear both the sprockets and the freehub body. Leaving it deliberately looser is not a good idea IMHO.

Having said this I can understand if you might not want it fully tight.

If the sprockets are very loose on the freehub body you will be able to move sprockets relative to one another. However I suspect that you have slightly worn freehub bearings; in this case the sprockets move slightly (en masse) wrt everything else on the hub/wheel.

Is this normal? -yes. [It is tolerable up to about 0.5mm of lateral play in the largest sprocket I guess.]

Is it a good thing? -no. The play will only get worse, and the parts will wear at an accelerated rate. There is also an increased chance of actual breakage since the pawls (typically two pawls in a shimano body) cannot share the load evenly if there is play in the body.

The cure is either to replace the freehub body, or to re-shim the existing one. I prefer to reshim used freehub bodies rather than use new ones because new ones always wear a little as they run in, but reshimmed ones have already run in and can last for many years before they need further attention.

When I rebuild them they are usually 'better than new' in that they have less play than most new ones and they will last longer before they need attention. The shims only give a relatively coarse adjustment so the parts are usually lapped to give zero play.

Unless yours is already pretty bad I'd suggest that the chances of it giving real trouble on a week's tour are fairly slight.

If anyone wants a freehub body reshimmed, PM me; I can usually do it via mail for £17 posted (UK), assuming that the bearings are not already rough/corroded. [If the bearings are corroded it can still be fixed (at extra cost) but it usually isn't worth it except for obscure freehub bodies that can't be replaced easily.]

On a shimano hub the freehub body is held onto the hubshell via a large hollow bolt that can only be accessed by removing the axle. This has a RH thread and must be unscrewed to remove the freehub body. They do occasionally work loose; if so the cogs move as described but when they move the whole wheel moves slightly too.

cheers
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~~~~~~~~~~~~~~~~~~~~~~Brucey~~~~~~~~~~~~~~~~~~~~~~~~
22camels
Posts: 302
Joined: 21 Sep 2013, 8:15pm

Re: cassette play

Post by 22camels »

thanks, very helpful.

i presume it's a shimano free hub - the bike spec doesn't say - it's a specialized tricross, rear hub "Forged aluminum, 32h, double sealed ball bearings, cassette, QR"..

as i said, tightening the lockring didn't seem to make a difference to the play i'm talking about. i'm wondering if it was there before or if it only came on when i changed the cassette.

it's not something you would be able to spot from just looking at the assembled bike, turning the pedals - there is no wobble at all in the cassette cogs, and i've seen a lot on some other bikes, even new ones (though that may be a different issue). The only way to see it is by removing the rear wheel and twisting the cassette back and forth.
Brucey
Posts: 44521
Joined: 4 Jan 2012, 6:25pm

Re: cassette play

Post by Brucey »

it is most likely a Joytech hub on a specialized bike. These look a lot like shimano freehubs but are constructed slightly differently internally. If you examine the cassette spline and it has a three-letter code on it, that is a good sign that it is a joytech freehub.

Such bodies can be replaced for about £25 a go but they often don't last that long before they develop play for the reasons I described earlier. They can also be re-shimmed as I described too.

If you examine everything carefully you should be able to identify what is moving to give the free play .

cheers
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~~~~~~~~~~~~~~~~~~~~~~Brucey~~~~~~~~~~~~~~~~~~~~~~~~
22camels
Posts: 302
Joined: 21 Sep 2013, 8:15pm

Re: cassette play

Post by 22camels »

thanks. I've left it with my LBS who'll most likely replace it.
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NATURAL ANKLING
Posts: 13780
Joined: 24 Oct 2012, 10:43pm
Location: English Riviera

Re: cassette play

Post by NATURAL ANKLING »

Hi,
Having fiddled with some freehubs recently (most of use will just replace with a new one as it needs tools patience and then some)
The joy tech 7 speed with you say three letters on the shell (captive hollow bolt) is a very similar copy to shimano 7 and 8 speed, two pawls.
Another 8 speed with NO markings, rubber seals has Three pawls :?: and the bottom race has 27 balls, 25 top, all shimano 7 & 8 speed have 25 balls :?: Captive hollow bolt.
Not stripped a shimano 7 speed recently so just going on what the eight speed has.

Are only shimano freehubs the design with hollow bolt into aluminium body :?:
NA Thinks Just End 2 End Return + Bivvy - Some day Soon I hope
You'll Still Find Me At The Top Of A Hill
Please forgive the poor Grammar I blame it on my mobile and phat thinkers.
Valbrona
Posts: 2696
Joined: 7 Feb 2011, 4:49pm

Re: cassette play

Post by Valbrona »

Anyone got a parts diagram on hand they could post?
I should coco.
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