Seized pulley

bompington

Picture the scene on the nastiest morning of the winter so far: 2º, heavy rain, strong headwind. 7am, nearly halfway through 20 mile commute to work, suddenly a nasty noise and resistance from rear mech.
Jump off to discover that yes, it is indeed a seized jockey wheel - better, I suppose, than the wrapped mech & trashed frame that were the cause of the last interrupted commute. Anyway, no tools with me, so set off walking home, got half way before a sympathetic cyclist in a Skoda stopped and offered a lift (thanks Sean).

So never mind my sob story, the question is: can I fix this just by a clean'n'lube? If so how easy?
How long does a rear mech last anyway? It's a SRAM Force - swapped from the crosser which is my winter / off road bike, but it didn't spend long on that - and is about 3 years old, perhaps 20,000km. Or would replacing the pulleys be a better option?

lemonenema

As far as Ive seen the Force derailleur has bearings in the jockey wheels rather than the cheapo bushings. You can service the bearings, Ive done it once with a stuck jockey wheel and its now turning but a little rough compared to the other one.
Take off jockey wheel, remove outer plate, wipe clean, use small bladed instrument / knife to lift off rubber seal (one on either side) again spray liberally with gt85/wd40 or similar solvent to dissolve old grease and rust. Inspect bearings, if a ball is completely dead then just replace the wheel, if they turn ok then dry with paper, re grease and re assemble).
20,000k is good life for a jockey wheel though and Id be surprised if the teeth arent overly worn too.

craker

I believe they're dry bearings, no point oiling them. A set of jockey wheels is pretty cheap and easy enough to fit (you just need some locktite to make sure the mech doesn't fall apart mid ride.)

I'm surprised it stopped you dead in your tracks - I remember finding a stiff jockey wheel when out on a ride and just put up with the extra resistance for the duration.

Edit: ^ I defer to Lemonenema's expertise here

keef66

IME once they start seizing up it's best to just replace them.

I generally go for the proper parts rather than blingy aftermarket stuff. One 105 mech the pulley mounting screws both set solid and rounded the hex sockets, so I just replaced the whole thing. Wasn't much dearer than Shimano jockey wheels and mounting screws.

lemonenema

Don't think they're dry bearings, the cheaper Shimano and SRAM ones are a simple metal-plastic bushing so just a thin layer of grease, the better ones have steel bearings similar to wheel / BB cartridge bearings, and some people buy ceramic ones for some reason!

bompington

Thanks for the advice

lemonenema wrote:

Take off jockey wheel, remove outer plate, wipe clean, use small bladed instrument / knife to lift off rubber seal (one on either side) again spray liberally with gt85/wd40 or similar solvent to dissolve old grease and rust. Inspect bearings, if a ball is completely dead then just replace the wheel, if they turn ok then dry with paper, re grease and re assemble).
20,000k is good life for a jockey wheel though and Id be surprised if the teeth arent overly worn too.

So I set about it last night. Never mind bladed instruments - as soon as I took the cage off the pulley in question simply fell apart (scattering the balls all over the garage floor :x ). The thin cover over the seal appeared to be bent? I'm fairly sure that this mech hasn't suffered any nasty torsional trauma but that might suggest it has...

So new pulleys ordered, hopefully arriving today. I'll watch for signs of trouble in the mech too...

lemonenema

obviously irrelevant now but if the balls fell out then the nylon cradle that retains them must have disintegrated, probably why it jammed for you.
Well thats an easy decision made!

veronese68

I know it's too late for you Bomp but a thought occurred to me. Cheap jockey wheels that are just a bush rather than roller bearings are probably more robust in the kind of weather you get in the frozen wastelands of the Arctic.

bompington

Ah *******.
Arrived prompt today... ordered the wrong part, of course.