Rear derailleur makes chain rub against sprockets

[Rickshaw Phil]

Gears are compact shimano with 12-27. I moved the bike in my car. Usually i leave the rear wheel on, but this i took it off too in order not to have to put the seat down. It's possible the rear mech was touching/touched the seat back :-( i guess thats whats done it!

Thanks for the welcome. I've been lurking a long time!

Ah, yes, if it was okay before that and causing trouble now it sounds suspiciously like that's what has caused the issue. As you've already mentioned taking it to be checked I can only concur that would be a good move. Hopefully it won't be anything too serious. Most likely is that the hanger has got bent - they are designed to bend/break easily to protect the frame from damage if the derailleur takes a knock.

 

[baljit]

Thanks again for the help

 

[bobdaspider]

rliu - I am also having similar issues with my rear derailleur / cassette / chain.
I have a retro Campy setup - 9 spd, 53 x 39 chainrings and a 13 x 26 cassette. The cassette, chain and rear derailleur (mid cage) are new and 9 spd - yet in small ring, rear derailleur is making chain rub against cassette - mainly gears 1 and 2, and 3 isn't completely clean. When I mentioned about using a slightly longer B screw on rear derailleur, the LBS were reluctant to go down this route re safety concerns etc. So, will re-read the responses here to see whether there is anything which may help me. Thanks.

 

[Ajax Bay]

@rliu is, amazingly (after 9 yeaars) still around so may answer.
Think it will be difficult to offer help unless you share a side on view with the chain in inner ring and largest sprocket (ie your lowest gear).
PS 9sp is not 'retro' - merely 1990s. I guess 'retro' is a function of the groupset's age divided by user's age (>50% ='retro' - discuss)
My Pat. 74 Nuovo Record and 5sp block is well "retro" (was new with bike).

 

[bobdaspider]

Hi Ajax Bay - apologies, maybe the retro tag was incorrect, and agreed a 5 spd block is certainly worthy of the retro tag.

 

[Ajax Bay]

Campy setup - 9 spd, 53 x 39 chainrings and a 13 x 26 cassette. The cassette, chain and rear derailleur (mid cage) are new and 9 spd - yet in small ring, rear derailleur is making chain rub against cassette

This is an entirely 'normal' set up and a short cage RD would be woman enough. So it suggests the (rotational) upper pivot spring (round the bolt to the hanger) might be malfunctioning.

 

[bobdaspider]

Thanks Ajax B - will have a look and maybe mention this to the LBS as they weren't keen to start using different length B screws on grounds of safety - which is understandable. It's just that I have to make my current setup work, since I won't be in a position to buy a new bike anytime soon.

 

[bobdaspider]

Hi Ajax B - forgot to post some pics - see attached of second gear (cassette: 13 x 26), mid (medium) cage RD which is 9 speed compatible. Gears 1,2 and 3 function but are noisey as the chain is rubbing. Any thoughts? Do I need a short cage RD?