Rear mech locking up

paulbox

Just after some advice please. This is a pretty new phenomenon for me, when my drive train gets a bit dirty and I’m putting it under strain, the rear mech is locking. Has happened a few times over the winter but a couple of weeks ago at Swinley it got really bad.

When I got home I did a thorough clean and removed jockey wheels, cleaned and lubed and refitted. Next couple of rides (dry last weekend) were great, didn’t miss a beat. This Saturday, not so dry and got splashed with mud etc. but nothing majorly excessive, and it was a complete nightmare again.

Chain was clean and lubed before the ride.
Bike is Yeti SB66
Drive train is full XT 2x10 apart from chain which is XTR.

What can I do to prevent this from happening again? I understand that if your mech gets completely gunked up it isn’t going to work effectively, but I’m just talking about splashes of the usual dirty gritty shit that we get at Swinley.
New jockey wheels/mech/chain? I just don’t want to waste money on things that won’t make a difference…
Thanks for your help!
Paul.

nicklouse

what do you mean by locking up?

Jockey wheels not moving?
pivot not moving?

Or....................

paulbox

It kind of stretches forwards and everything just locks, I have to peddle backwards slightly to free it up and enable peddling again (until it does it again!). Obviously not great when climbing.

Chunkers1980

Is when you change gear?

freezing77

PaulBox wrote:

It kind of stretches forwards and everything just locks, I have to peddle backwards slightly to free it up and enable peddling again (until it does it again!). Obviously not great when climbing.

Could be chain suck rather than at the back end it is at the front end of the drive chain.
http://www.fagan.co.za/Bikes/Csuck/

paulbox

Chunkers1980 wrote:

Is when you change gear?

No mate, just when pushing on/climbing.

paulbox

freezing77 wrote:

Could be chain suck rather than at the back end it is at the front end of the drive chain.
http://www.fagan.co.za/Bikes/Csuck/

I think you're right, all the symptoms sound spot on. I have experienced chain suck previously but nothing that actually made the drive train lock up completely.

Will have to inspect my chain rings when I get home, are XT 2x10 small rings replaceable?

Thanks for the link.

BG2000

Are you on the bike pedalling when you notice the rear derailleur pulled forward, or is it once you're off the bike again ? Either way, surely you can see if you've got chain-suck, i.e. the chain wrapping back round on itself over the chainrings....it's quite noticable

paulbox

Mainly when I'm climbing, agree that it would be quite obvious what was happening if it was on a work stand, not quite so obvious climbing switchbacks etc...

Can you see it when riding? Would have to stick head out to the right then look back at the chainrings.

nicklouse

PaulBox wrote:

Can you see it when riding? Would have to stick head out to the right then look back at the chainrings.

Just looking down tends to work.

Also if you have to stop then you can see what has happened.