Chain keeps coming off.

ccull123

Hi all,

Currently running on 105. Whenever I put the chain into lightest gear the chain keeps slipping off of the sprocket. I have no problems iin any othr gear except the lightest one.

I had a fall on my bike about 6 months ago and the rear deraileur got a bang but am wondering do any of you have any suggestions.?

Afraid I cannot put pictures up of the rear deraileur at the moment.

ashleey

Assuming your lower limit screw is set correctly then you may have bent the derailleur hanger. They are designed to take the forces so that your derailleur survives a crash mostly. Look to check that the pulleys are straight down from above when in the lowest gear

Tonyandthewhale

You might have to loosen one of your limit screws. There should be two screws on the derailleur, one for limiting how far outboard the derailleur can move and one for how far inboard it moves. Figure out which one controls inboard movement and turn to see if that makes a difference (turn it quarter or half turns at a time, you don't want to remove the screw).

If that doesn't work its possible that your derailleur hangar was slightly bent in that fall you mentioned but usually this would affect all the gears rather than just the lowest one.

Mycroft H

ccull123 wrote: »

Hi all,

Currently running on 105. Whenever I put the chain into lightest gear the chain keeps slipping off of the sprocket. I have no problems iin any othr gear except the lightest one.

I had a fall on my bike about 6 months ago and the rear deraileur got a bang but am wondering do any of you have any suggestions.?

Afraid I cannot put pictures up of the rear deraileur at the moment.

Derailleur hanger or limit screws off. Careful your chain does not eat your spokes.

Any decent bike shop should fix this for little money. You could do it yourself by replacing the hanger and adjusting the Low limit screw (or you could bend the old hanger back into shape with an adjustable wrench)

ccull123

Thanks everyone. Ill give it a try when i get home this evening. One of my mates in work stressed that I shouldnt cycle in the lightest gear until this is fixed. He said there was a chance i could wreck all the spokes/deraileur.

thanks again

Chips Lovell

I presume it's slipping off towards the spokes and not down onto a smaller sprocket?

If it's started happening since the accident then it's more than likely a bent hanger and not the limit screws. New hanger should fix it.

ccull123

slips towards the spokes. Is a new hanger expensive?

ashleey

Not at all. They are designed to be easily replaceable

Chips Lovell

ccull123 wrote: »

slipper towards the spokes. Is a new hanger expensive?

Usually around €15

BTW, your friend is right. Don't cycle in that gear until you fix it as you risk causing more damage.