Loose sprockets

dpc1l said:

Lockring holding the sprockets in place has started to come off recently. ... - does anyone have any ideas what's causing this?

My immediate thoughts are not enough torque, or worn out parts. The lockrings are serrated, so repeated disassembly and reassembly will eventually reduce their locking ability.

dpc1l said:

I'm thinking of using Loctite to keep it in place - is that a good idea?

The risk I can see with that is that given the diameter of the lockring (i.e.the amount of loctite you'll end up using) you might have trouble with future disassembly, the bond might become too strong.

Thanks lot for your advice!!

Right, It has just happened again!

AA friend serviced my bike for me this weekend and had a look at this problem. It all seemed fine while he was here, and it worked properly. He said the lockring is designed so the thread is in the opposite way to the direction the wheel moves, so it shouldn't work loose.

I am weighing up my options - I got the bike in a special, so didn't pay very much for it. It also is a lower end of the spectrum bike so am loath to spend too much fixing it. Admittedly, my friend is not a trained bike-mechanic, but he has a lot of experience and knowledge about fixing bikes. If he can't fix it, I assume it will be quite costly if I take it to a bike shop.

Should I buy a new cassette (I think it is a cassette as opposed to a freewheel, as all the 'cog's are separate) Would this sort the problem out?
Should I buy a new back wheel?
As I won't be using the bike all that much between now and Christmas, should I get rid of the bike (don't want to throw good money after bad) and get a nice one in the Christmas sales? One that I won't mind spending money fixing.

Thanks a lot for reading

My initial thought would be that your cassette (the stack of spokets) is not the right size for your freehub body. I have seen several occasions where a person tried to put a 7-speed cassette on an 8-speed freehub body. What ends up happening is the lockring tightens against the lip of the freehub body before it torques down on the cassette. Though it feels like you have tightened it, the cassette is still floating with no tension on it. A spacer or two behind the cassette can move the cassette forward enough so the lockring is clamping on the small cog, keeping your cassette in place.

Properly installed, your cassette lockring really should not come loose. As the previous poster mentioned, it is serrated. Also, the cassette is not turning on the freehub body, so there is really nothing that would force the lockring to come loose.

Definitely don't throw the bike away at this point. At the very, very worst you would have to replace your rear hub and cassette. Though it would cost a bit, and unless you know how to build a wheel, you would be paying your bike shop to do it (or buying a new rear wheel), it would definitely be cheaper then a whole new bike.

Cheers,
Juba

dpc1l said:

A friend serviced my bike ... He said the lockring is designed so the thread is in the opposite way to the direction the wheel moves, so it shouldn't work loose.

Your friend might be running on outdated info. There was a time when the smallest cog WAS the lockring, and with that setup each push on the pedals tightened it further. With separate cogs/lockring this action isn't as pronounced anymore.

Quoted post said:

I assume it will be quite costly if I take it to a bike shop.

(Assuming the rest of the bike is in good working order) A new cassette doesn't have to be that costly, ($30) and replacing it is a 5-minute job. But if Juba is right about this being a fitting problem, then a simple spacer/washer should be able to solve the problem even cheaper. Depending on how much you have ridden (and the quality of your LBS) they might find some other stuff they'll recommend you to have replaced while they're still at it. That might up the price though.

Quoted post said:

Should I buy a new cassette

Not unless there's something wrong with it. An honest LBS should be able to tell you that free, at a glance.

Quoted post said:

I think it is a cassette as opposed to a freewheel, as all the 'cog's are separate

It sounds like that. The cogs CAN be handled separately, but usually they're assembled into one unit, with maybe a couple of the smaller ones loose. If yours are ALL loose there is a strong possibility that someone has fiddled around with your cassette earlier, and maybe lost a spacer/washer somewhere in the process. Does it shift all right otherwise?

Quoted post said:

Would this sort the problem out?

I can't say, since I don't know the precise cause of your problem.

Quoted post said:

Should I buy a new back wheel?

Well, if you stumble on to a (used) wheel with the right number of cogs for a very good price, why not? But you shouldn't actually NEED to to get your problem sorted.

Thanks a lot for your responses.

I have used the bike four times a week for about three months, and it has just started happening! I tightened the lockring as tight as I thought was possible, and the sprocketts had no play at all. When I started riding, it started loosening straight away, and came off after a very short distance 🙁
Previously, the one pedal kept working loose, which seems to have stopped happening now.
I think the new cassette option looks good

Thanks again