Locking chain

[Thompson]

I was on a ride last week and after about 20ish miles the chain kept locking which nearly sent me flying each time as it just wouldnt budge unless I really forced it numerous times. One guy thought it may be frost/ice as it was cold! (we had frost on our faces!) we've tried spraying it with some proper cleany stuff but it still locks now and again. Just before it locks, theres a weird clickin noise, im not sure whether the its the chain, or the actual cogs.

Any suggestions?

 

[Roscoe]

Give it a good clean and lube, had the same problem when then the Bike's been left in the shed for a while.

 

[deanbmx]

Could be a lack of lube in the freehub. May be worth stripping it all down, cleaning & re-lubing.

 

[Monkspeed]

When it locks does it actually come off the cassette and is jamming against the wheel or against the chainstay beam?

 

[rusky]

How many miles have the chain & cassette done? Could be worn?
Or as deanbmx has suggested, the freehub.

 

[Thompson]

It doesn't come off, it just completely locks, I can move it back a touch which I was doing to unlock it, moving it back as far as it would go then really pushing it forward. I'm not sure what it was jamming on as when we stopped to look, there appeared to be nothing. As to the miles, god knows how many, it's coming up to 4/5 years old (I couldn't get a new one as it's been my main bike for so long ) but it has took quite a few bashes etc and has done ALOT of miles.

 

[rusky]

I would replace the chain & cassette before it breaks & causes you injury!

 

[Thompson]

mm yeah, i'll have the bike shop have a look at it to make sure sometime next week :P

Thankyou all.

 

[Scilly Suffolk]

Sounds like the hub: the chain would have to be practically solid for you to be unable to pedal, especially as you are rolling it back then forwards to free it.

 

[Thompson]

So what would I need to do with the hub if it is causing the problem? Just give it a full work up or as Rusky said just replace the possible things causing bother? Though one guy I was with mentioned that it seemed harder to pedal mine backwards compared to normal. As if I was putting more effort in must to turn the chain, like it was stiff or something. But I don't know much about how bikes work really. :P

 

[Scilly Suffolk]

Two flavours of hubs/sprocket clusters:
1) the cluster contains the mechanism that allows the wheel to keep turning when you stop pedaling; this is known as a freewheel and is found on older bikes and lower-end modern bikes, usually 7 gears or fewer.
2) the hub contains the mechanism that allows the wheel to keep turning when you stop pedaling; this is known as a freehub
and is found on modern bikes, usually with 8 or more gears.

It is relatively straightforward to change either.

What sort of bike do you have? How many gears? Can you see a model number on the gear cluster?

 

[Thompson]

ahh thanks, and its the Carrera Kraken hardtail mountain bike, old old verison :P and it has three gears on the left and 9 on the right. And I cant get into the garage to see the bike as my dad is making a fence at the moment so it'll have to wait till im next out on it.

 

[ColinJ]

Chainsuck, perhaps?

 

[Scilly Suffolk]

You probably have a freehub and most likely a cheaper Shimano one.

Their freehubs can be stripped and serviced, but in practice you'd be better off replacing it.

Some more info here and an example "how to", to give you an idea as to whether it's a job you (or your Dad) would like to tackle.

PS It's difficult to be certain what your problem is over the web, so do get a second opinion in person before spending any money.

 

[andrew_s]

Does the bike freewheel when the chain jams? If it does, the problem can't be with the freehub/cassette, or backpedalling would be OK
Other possibilities:
Chain jammed between seatstay and smallest sprocket
Chain jammed between inner chainring and chainstay
...Both these would be easily visible if you stop and check whilst the chain is still jammed
A broken ball in the BB bearings jamming up the chainset
An undone QR (a bump allows the axle out of the dropouts, and the chain tension then jams the tyre against the chainstay bridge)