Derailleur probs, please help!

OrangeSmartie

Hello,

This isn't strictly a road bike question, but I hope someone can answer it.

I've recently replaced the chain and cassette on my ridgeback hybrid and I'm having problems with the rear derailleur. Basically, when I'm on the smallest (of three) chainwheels, the chain "catches" and pulls the jockey wheels upwards and forwards so that the derailleur contacts the frame. This problem only happens on the small chainwheel, not on the other two, but it means that I'm unable to use my granny gears. It also only seems to happen under load. The previous cassette was a shimano 8speed, 11-34 (I think), which I have replaced with a shimano 11-32. Both old and new chains were SRAM.

If anyone has any ideas, I'd be most grateful - this is doing my head in.

Cheers,

Pete

maddog 2

sounds like you're getting chain suck, due to a worn chainring.

have a look at the teeth on your granny ring. If they are hooked or damaged then they can fail to release the chain properly. The chain then wants to go around the chainring again, which pulls the rear mech forwards as the chain tension increases.

Or it's something else.... :?

Hugh A

Is the chain the same length as the old one?

Could be the upper derailleur cog is too close to the cassette and is jamming the chain? Do you hear any rubbing noise before the problem? The loop of chain going over the upper wheel should be near the cassette sprockets but never touching. The b screw by the mech attachment bolt changes tension to adjust this and when you screw it all the way in the gap should get bigger.

OrangeSmartie

Thanks for the quick replies. I have actually ordered a new chainset, so if maddog 2 is right, I should find out shortly.....

The chain is almost exactly the same length as the old one Hugh; I think previously it was slightly too long so I shortened the new one. I haven't noticed any rubbing of upper jockey wheel on cassette, but I'll check tonight.

OrangeSmartie

Quick update - fitted the new chainset last night and no chain suck. It's good to know what was happening, because even though I do loads of miles and change chains etc I've never come across this phenomenon before.

Pete

Voytek

hi

i'm not having so drastic problems with my deraileuur but what I noticed is I got some strange high pitch sounds coming out of it. it's like clicking or ticking and it happens only when I pedal/gain speed. I have checked the chain is not rubbing against anything and it's okay so I'm a little bit lost. what causes the sounds? i'm thinking about giving bike proper cleaning - reason it all started after i had an 1 hours riding session in the rain so maybe it's just filth in the system causing that. any ideas fellas?

LingfieldXC

i tried fixing my front mech on my new 1.7 today as it was rubbing due to cable stretch. Took me ages to do it. Finally managed it in the end but will not be doing that again in a hurry. It was weird because I fixed my sister's bike's front and rear mech which was really easy but the road bike was much harder. I need to do my mtb aswell. Lots of maintainance at the mo.

I found that my sis' bike was clicking. It was the cog of the rear deralleur (spag?) touching the teeth of the largest ring on the casette.