Gears Slipping/jumping

[The Central Scrutinizer]

Whenever i am cycling up an ascent and putting pressure on the pedals the gears start slipping/jumping and even comes to a point where the chain comes off.It doesn't happen on the flat.
Although it does happen in the bigger cog it's mostly in the smaller cog(granny ring)and in the higher gears.
I know you have the barrel adjuster and the two limit screws but i'm reluctant to try this for fear of making it worse.
Rather than take it to my LBS i thought i would ask here first.
Cheers

 

[fossyant]

Worn chain/cassette ! You aren't going small small are you, as shifting ramps can try and shift the chain up

 

[T4tomo]

sounds like a worn chain and /or cassette to me. measure chain and replace if worn / elongated. if it still happens then its new cassette time.

 

[Ajax Bay]

How many km since you fitted a new chain?
How many km since you fitted a new cassette?

 

[I like Skol]

IME even a badly worn drivetrain will work fairly well if correctly adjusted, until it gets to the point of sharks teeth on either the cassette or chainset. The problems generally start if one of the components are replaced (i.e chain, cassette or chainring) and you then get terrible meshing issues between the worn and new parts.

Has anything been changed recently?

 

[The Central Scrutinizer]

How many km since you fitted a new chain?
How many km since you fitted a new cassette?

Chain maybe 1200 Kms
Cassette rough guess 10-11000 Kms
Here are some pictures of the chain with the wear check tool and the cassette.

 

[T4tomo]

Cassette rough guess 10-11000 Kms

new cassette time then, and hence new chain too as you don't want a worn chain on a new cassette.

 

[The Central Scrutinizer]

IME even a badly worn drivetrain will work fairly well if correctly adjusted, until it gets to the point of sharks teeth on either the cassette or chainset. The problems generally start if one of the components are replaced (i.e chain, cassette or chainring) and you then get terrible meshing issues between the worn and new parts.

Has anything been changed recently?

Only the chain when the bike went in for a service in february

 

[I like Skol]

If the chain has run ok with this cassette until now I would be surprised for it to be a worn chain/cassette.

How are the teeth on the chainset looking? You might be investigating the wrong end or maybe the indexing has shifted for some reason.

 

[antnee]

Yes you've posted some good pics of the Chain and Cassette could you post some up of the Chainwheels ? Though I'm sure that some more adjusting of the Rear derailleur could be perhaps fortuitous? do you experience the same faults when bike is in the work stand ?

 

[The Central Scrutinizer]

Yes you've posted some good pics of the Chain and Cassette could you post some up of the Chainwheels ? Though I'm sure that some more adjusting of the Rear derailleur could be perhaps fortuitous? do you experience the same faults when bike is in the work stand ?

There is no skipping when the bike is on the stand.

 

[Ajax Bay]

11,000+ km is a great longevity for a cassette to have achieved. Very surprised the new chain didn't immediately skate on first use (and every high torque use/occasion) - maybe it did: the OP does not say/exclude.
Replace cassette and chain at your earliest convenience. The chain will be close to or beyond 0.5% elongated already. If just the cassette is replaced, the 'old' chain (1200km on it) will skate on the 'new' cassette.
No skating on the stand would be expected: you can't get anywhere near the power needed.

 

[The Central Scrutinizer]

@Ajax Bay
Thanks for your input and everybody else who posted.
The gears have only been playing up in the last week.
I’m going to take it in to my LBO and see what they say.

 

[I like Skol]

@Ajax Bay
Thanks for your input and everybody else who posted.
The gears have only been playing up in the last week.
I’m going to take it in to my LBO and see what they say.

In view of this vvvvv comment, probably the best solution really.

I know you have the barrel adjuster and the two limit screws but i'm reluctant to try this for fear of making it worse.

Could be sub-optimal indexing, but in view of the cassette age I think a new cassette & chain is probably sensible, even though on the face of it they don't appear to be in terrible condition.

 

[The Central Scrutinizer]

Just to finish off this thread!
I took the the bike into my LBS and he said the the chain and cassette are ok but it's the rear mech hanger which is slightly bent.
He sorted that out and everything is back to normal.