carnt back pedel

[busdennis]

its a 10 speed 105 bike. the gears are indexed well and all works A! apart from when I need to turn the pedals backwards ie at junctions to get the natural starting point to push away. the problem being the chain falls of the top cog of the derailleur and jams. I'm lost as the derailleur dosent look bent and like i said the gears have good index. ideas please

 

[Specialeyes]

Inner limit screw perhaps? I presume we're talking about the rear mech.

 

[raleighnut]

Sticky Freehub?

 

[busdennis]

How worn is it all? Hooked, or shark fins, profile to cogs and chainrings? Can you pull the chain away from the chainring at the front?

all in good condition

Sticky Freehub?

will try another wheel

 

[lpretro1]

Freehub body on way out for sure....

 

[Globalti]

Sticky free hub, sticky jockey wheel or seized chain.

 

[winjim]

Top cog? Do you mean largest sprocket or upper jockey wheel? I'm guessing the latter.

 

[busdennis]

upper jockey wheel

Top cog? Do you mean largest sprocket or upper jockey wheel? I'm guessing the latter.

upper jockey wheel

 

[Tim Hall]

So, playing that back in my head, the chain passes cleanly over the cassette but the jockey wheel doesn't let it pass. Does the jockey wheel turn freely with the chain removed?

 

[winjim]

upper jockey wheel

upper jockey wheel

OK. Has the mech been disassembled and the jockey wheels mixed up? They are not identical. The upper wheel is designed to have some sideways float to aid with indexing. Do the jockey wheels spin freely with the chain removed? They are prone to gunking up with chain lube and road muck. Are the screws holding them done up too tight? The top one needs the aforementioned float.

 

[Willam]

Mine was doing that too, serviced my hub and it's fine now.