I built up a new bike – fantastic – and after a few laps of spooky wood the shifting went to pot – pretty much unrideable. Trail side investigations showed all well but when I got home I found this:

Sorry the photo focuses on the wrong spot – but one if the bearing outer doofers is mangeled – fubar. There is also major scarring on one side or the jockey. Now I’ve had no crashes, dengs, scrapes, anything. I’ve had the mech from new – about 200 miles-ish. An SLX GS. The chain is plenty long enough.

Any ideas what could cause a jockey to get so fubar in maybe 50 miles?

#Edit – just to be clear – the one the right hand of the photo has pretty much “turned itself inside out” with significant scarring to both faces and the plastic wheel. In the shed I would have to hit that pretty flipping hard to get it to turn inside out. So I’m stumped.

Was the axle too short?

Was the axle too short?

– #Mmmm. New bike was for 135 (god I better double / triple check that) before I fitted my old wheels.

OK I’ve checked – and yep frame and wheels are “normal QR” – they just fit in to each other and the spec’s agree.

had you been riding somewhere where the soil/surface was gritty? do you clean it often? had you stripped it and put it together too tight? i’m guessing when you say the mech has done 200 miles but thats happened in the last 50 then you might have stripped it and cleaned it. Looks like some gouging on the jockey wheel as well, something abrasive get trapped in the cage when flying down spooky and you didnt notice first time round?

bit of wire got caught up?

put back together wrong?

50miles from new?

Was it a new Mech?
I found the SLX jockey wheels rubbish and they could wear out super quick compared to XTs.
They look like they just have a metal tube going through the jockey,anything gets past the seals and it’s going to grind away quick.

Hi Haggis – I ride the same old all the time (I’m lucky!)

Mech was taken off a double and bash bouncy bike that had done a few months of GT / Inners with no issues. I never stripped it. There is now major jouging on the lower jockey wheel.

What gets me is usual stuff- perfect shifting – 30 secs later it’s fubar.

It looks like the grit has caused the dust sheild to bind to the jockey wheel and span it around with the wheel where it’s basically been bored out by the inner sleeve that’s remained stationary as it’s supposed to.
Not seen that before, you’d think the dust sheild would just cut a groove in the composite wheel and allow it to spin freely.
Every day’s a schoolday.

Wow – lots of responses since my last! Cheers!

I’ve had the mech from new. All for a double and bash (all M660 spec sheet stuff). Then everthing got swapped to the new bike – I’ve never had to touch the mech.

What gets me is how much bloody force it would take to turn that race inside out – and honestly – I never noticed a thing.

Sorry didn’t mean the axle on the wheel I meant the axle through the jockey wheel. I have destroyed a jockey wheel previously because the top and bottom jockeys wheels have different axles

Kind of looks like the chain has been jammed between the cage and the jockey? Wouldn’t have thought there’d be enough room but worth a thought.

Looks perfectly normal to me, just a jockey wheel with mud on it. The groove is where the metal shield sits. If there’s damage to a shield it will be because you picked up a branch. It happens.

my guess it is seized and was turning the wrong bits and when it wore thru it failed.