Rear derailleur snagging

[edwarj123]

So I just went out for an hours blast in my lunch time as I'm working from home ;-) From about half way round my normal 10 mile loop I felt something that I thought was from the front mech catching etc but after a while caught site of the bottom of the rear derailleur sort of catching and jumping/moving forward/snagging when pedalling under pressure.

Pretty sure I didn't hit anything to bend or move anything.

Only thing is that it's been raining most of the morning so wasnt too muddy but pretty wet and when I went out Tuesday night it had been dry for a week or so and put muc off dry lube on after my ride. When I rinsed the bike off when I got home today the chain and cassette were spotless - do you think the lube just came off to quick in the wet or is it something more do you think? The jockey wheels are not worn - they're only about 6 weeks old -always something!

Thanks,
Justin.

[PMC101]

if i were you id check and redo the limit screws and also the cable tensioner.

It maybe as simple as the tensioner got knocked or pushed abit and making the derailleur snag abit from the chain.

[Hobo]

That sounds like it could be a mild case of chain-suck. Chain might be sticking to front ring - not enough to jam up against the frame, but just enough that will pull the derailleur forward.

The lack of lube would cause it.

[steve_sordy]

Sounds like something on your chain is catching the derailleur jockey wheels and dragging the derailleur backwards. Eventually whatever it is goes past and releases the derailleur to "leap forward".

Could be a piece of debris in your chain, if so would happen once per chain cycle.
Could be something on your jockey wheels, doubt it as there are so few teeth it would be chattering not just leaping forward.
My favoured culprit is similar to chain suck. I know one of the bike mags gave a high rating to Mucoff wet lube, but they didn't compare it to Finish Line wet lube. And my chain suck only stopped when I started using Finish Line instead of Mucoff. I would imagine the Mucoff dry lube is even more fragile!

Switch from a dry lube to a good quality wet lube like Finish Line, but make sure you wipe off the surplus if its dry, leave it on if its wet.

[edwarj123]

Cool, sounds like an easy issue and easy reolution then - fingers crossed.

I saw the sun at the weekend and think I was a bit premature with the dry lube - wishful thinking. Given the bike a good clean and gone back to the old faithful Finish Line Wet lube for the time being - let's see what happend.

Steve - they should make you an amabassador for that stuff - are you on commission ;-)

[NorthernMatt]

Had a similar problem on sunday as well, turns out I've got a bent chainring which was holding onto the chain every turn and pulling the derailleur up until it stopped. Had to try and bash the ring straight to get round the trail. New one is on order.

[steve_sordy]

Steve - they should make you an amabassador for that stuff (Finish Line) - are you on commission ;-)

I wish!
I learned the hard way that Finish Line is excellent stuff. So I pass that on for free. If someone knows of anything better, let me know and I'll swop!

[fredmundo]

I always use finish line wet.... Never bought dry. I live in the peak district!

[JonathanL]

Nearly Fred! Miserable this afternoon and evening in the Hope Valley. Slow, wet drizzle. Might get rid of a bit of dust for the weekend though. Never known it so dry in March in the 11 years I've lived here.

[MTBLeague]

The key to this one is how frequently and in what gears it skips, could be many things from a bent tooth, through stiff link in the chain to.....

...the only time I ever got these symptoms is in winter with ice and snow building up on the lowest derailleurs teeth, it's obviously not that, a bit of observation will clear the mystery, let us know.