Cassette/block becoming unuseable

[QUIST]

Is there any way of predicitng when this is going to occur?

IE when it will not engage with the powetr train but just spins freely?

And am I correct in saying there is no way of making it work again?

Odd Gloves aka Toby

[NUKe]

try a liberal dose of wd40 into any nuck or gcranny you can find. its more than likely the pawls are stuck if the cassette is spinning or is the chain riding over the sprocket in which case it is passed its best.

[Mick F]

I think - by your post - that you have a freewheel block rather than a modern cassette?
If so, there is no way of predicting WHEN, more like predicting IF.

I my experience of freewheels, they need lubricating and servicing. If that is done, they will never fail. If it's not done, they MAY fail - and usually during winter time.

Remedy for you?
Remove the rear wheel and lay it down with cogs uppermost.
Spin the freewheel backwards and at the same time spray in some WD40 through the joint where the bits rotate vs the solid bit.
If you can get some lube in there, it may live again.
Failing that, I would strip it down to fix it ........... or buy another.

Good luck and get back to us.

[Brucey]

with care it is possible to disassemble both freehub bodies and screw-on freewheel bodies. However, few can be bothered to do this. NUKe and Mick's suggestion is exactly the right thing to try first.

Free play in the bearings, water ingress, lack of lubrication, corrosion can all cause failures where the freewheel is 'free' in both directions. So can the use of grease as a lubricant for the freewheel pawls; it will cause them to stick at inconvenient times.

Occasionally one of these mechanisms will fail completely, but it is very rare that one of the above is not a contributory factor.

cheers

[meic]

In my experience you get a fair amount of warning before they totally fail. You may miss some of the warnings but you are unlikely to miss them all.

The last one that I disassembled had had the bearings rust and collapse and the outer part of the freehub was wobbling fairly noticeably on the axle. Yet I still made it home.

[QUIST]

Thanks for all the replies especially Mick's - there was no warninmg bar a one off clunk when starting pedalling and I've tried the WD40 option but to no joy yet.

There's been no wobbling but I suspect it may be a gonner - probably due to my poor maintnenance,

Odd gloves

[Brucey]

is it a screw-on freewheel or a freehub? Brand?

cheers

[QUIST]

After visit to local friendly bike shop last night realised it is a cassette, It is a Shimano supposedly sealed but it is the intererior bit which has gone,

Toby

[Brucey]

easiest fix is a new freehub body then. Just unbolts once you have the cogs off and the axle out. If you fancy stripping it down and refurbing it....

I have stripped and refurbed dozens of freehub bodies, so it can be done without doubt. However you usually need a tool to engage with the RH bearing race which is on a LH thread. I had to build a special tool for this purpose and since then I have not failed to overhaul a freehub body. The bearings adjust -to an approximation- using shims.

Why bother? Well, although it happens rarely to most people, IME if they are left with slightly loose it is only a matter of time till they are at some danger of slipping under load. The reason for this is that with play present, the pawls 'squirm' on their loaded faces and this eventually wears to allow slippage. Even the bearings wear faster once there is a little play; they are usually scuffing and sliding about too. With the bearings correctly adjusted the pawls and bearings do not 'squirm' and they do not wear in the same way.

For a mass-produced product the standard shimano freehub body is a very well made item, but it is not without its flaws. Although some never need any attention, very often from new they have a little play in them, or quickly develop some in use. I have found that if they are used for a short while (say 1000 miles or so) then adjusted, they then run happily for extended periods (10000 miles or more) without further trouble, adjustment, or even appreciable wear. Note that it is pointless adjusting them when they are brand new because a little wear in first use seems inevitable.

The shims for bearing adjustment come in thicknesses down to ~0.1mm. Unfortunately this isn't thin enough to allow really accurate bearing adjustment, and thinner shims would be flimsy. My trick for adjustments of less than 0.1mm shim thickness is to start with the bearing slightly loose, (then using circular motions) to 'lap' the rear face of the RH bearing cup using 600grit abrasive paper on a perfectly flat surface until the bearings are 'just right' when reassembled and the RH cup is tightened. You can measure the length of the RH cup using verniers to see how much is being taken off.

This process takes a few minutes to get right, but IME it can make the difference between having to do it again, -possibly ever- and not.

[edit; some units have no seals, but where there are seals, they will work properly if there is no play in the bearings, and may not otherwise, which results in an evil spiral of water ingress and destruction.....]

cheers

[reohn2]

After visit to local friendly bike shop last night realised it is a cassette, It is a Shimano supposedly sealed but it is the intererior bit which has gone,

Toby

The hub will need to be stripped to to effect a repair or replacement,if you're comfortable with this it entails remomoval firstly of cassette (you need a chain whip,cassette locknut tool and an adjustable spanner),the axle and loose ballbearings are then removed,(you'll need a pair of cone spanners).The freehub (the bit giving trouble) is then unscrewed from the hub (with an 10mm allen key)and either replaced or relubed,I find if I gently prise the rubber seal from the back of the freehub then squirt inside with either TF2 or aerosol grease the pawls are freed up.
If you aren't comfortable stripping the hub down the LBS should be able replace the freehub body for around £30/40.

[meic]

If you are going to replace the freehub yourself, I find that for the cheaper hubs which I always use on my bikes (Tiagra, Deore LX) it is normally cheaper to buy the whole axle hub unit. Then you can replace as much of the old hub as you feel like.

There is a great thread on the forum going through a freehub service in Haynes manual style
but it is for a Uniglide freehub and yours probably isnt that type.

[BigG]

Just an added word about the old freewheels. The good ones (Suntour and most Shimano) will last almost indefinitely if kept clean. In normal riding, they have no moving parts as everything is stationary relative to the hub. They only wear when freewheeling and even then the bearings are very lightly loaded: only the pawls and springs experience any significant wear. Keeping freewheels clean is not that easy, however. I remove mine every year (twice a year when I covered more mileage) and run 3-in-1 oil through them from the back while spinning them by hand using the unsealed gap between the inner and outer body as the entry point. I use quite a lot of oil, maybe as much as an egg cup full, adding a few drops at a time until it disappears inside the mechanism. The oil starts by emerging black but finishes by coming out looking fairly clean. I then leave it to drain for an hour or two before reassembling the wheel. In this way, one freewheel hub lasts for at least several sets of sprockets - including reversing them - until it is cheaper to buy a complete new unit instead of replacing the most worn sprockets.

[Brucey]

In normal riding, they have no moving parts as everything is stationary relative to the hub. They only wear when freewheeling and even then the bearings are very lightly loaded: only the pawls and springs experience any significant wear.

this is quite true as long as there is no play in the bearings. As soon as there is play, wear may be considerably accelerated when pedalling since everything is squirming about somewhat and the load isn't spread over as many balls as it should be. Mind you, it is nothing like as bad with a traditional freewheel since everything is a fair bit bigger and stronger than with a freehub.

cheers