Chain Coming Off

[Hip Priest]

Recently, I've had a bit of trouble with my chain coming off. It has normally been when I've been down-shifting whilst slowing for junctions or when I've been wheeling the bike out of the garage backwards.

The other day the chain came off when I was accelerating out of the saddle, with disasterous consequences (see other thread).

Anyway. Tonight I removed my cassette and gave it a proper degrease and clean. As far as I can tell, it is not worn to any great degree. I then replaced the chain.

I rode round the street a bit thinking 'Wahey, job done', when - you guessed it - the chain came off! What could be causing it? I'm guessing the fact it happens when I wheel the bike backwards means it could be a problem with the rear derailleur and / or jockey wheels.

I'm hoping it's something simple to fix...famous last words.

 

[02GF74]

not much detail given but do you have more than one chainring? if so, is the front mech adjust correclty?
is the chain the correct length?

 

[Hip Priest]

not much detail given but do you have more than one chainring? if so, is the front mech adjust correclty?
is the chain the correct length?

I have a single chainring and an 8 speed cassette. How would I check if the chain was the correct length?

 

[02GF74]

let's back pedal as it were - I assumed it was coming off the chainring - correct?

to answer your question, chain is put on largest chainring and largest rear sprocket and add 2 links. it could be the derailleur is not keeping the chain under tension, either chain too long or spring is weak.

any stiff links in the chian? are teeth on chainring worn?

 

[Hip Priest]

let's back pedal as it were - I assumed it was coming off the chainring - correct?

Correct

to answer your question, chain is put on largest chainring and largest rear sprocket and add 2 links. it could be the derailleur is not keeping the chain under tension, either chain too long or spring is weak.

I'll check that out the morning, thanks.

any stiff links in the chian? are teeth on chainring worn?

The chain is new so shoud be fine. The teeth on the chainring haven't lost their shape either. I've done 1500 miles on the bike in total.

 

[sidevalve]

As above I'd check for any stiff chain links. A friend of mine had a similar problem with a newish chain, a stiff link that sometimes kinked, took ages to find what was going on.

 

[mickle]

Bent hanger.

 

[Hip Priest]

Thanks for the advice guys. I'll check all suggestions tonight. Another question (sorry): Is there an easy way to tell from sight if a cassette or chainring is worn? The teeth still have there shape, but I'm concerned that running the same chain for 1500 miles may have ruined m drivetrain.

 

[Hip Priest]

Right. I've tried everything, and it still keeps happening. It's going into the shop before I had a nervous breakdown!

 

[mickle]

Bent hanger?

 

[Hip Priest]

Bent hanger?

It seems fine, but thanks for the suggestion.

I think the cassette and / or chainring is knackered to be honest - I'll be commuting on the road bike still I can afford the repairs!

 

[RecordAceFromNew]

let's back pedal as it were - I assumed it was coming off the chainring - correct?

Correct

Possibly chainring or chain link bent sideways. Put bike on stand or ask someone to lift it so back wheel off the ground, look from above while you "back pedal" with your hand.

 

[PatrickPending]

I'd go with Mickle on this one!

 

[Hip Priest]

As I've said, the hanger looks fine to me. It's going into the LBS tomorrow so I'll let you know the diagnosis!

 

[Hip Priest]

Right, I've just picked the bike up from the LBS. And the cause of the problem was...a bent hanger! Not just a bent hanger but a 'badly bent hanger'. So I've learned that I'm blind and I should listen to Mickle!