snapped derailleur

[Groovemachine86]

Howdy

Whilst on a mini tour in France last week, I changed down a gear on the flat not pedalling hard then I think the chain broke (cus there was a big slip) then the chain instantly wedged its self in the rear mech, which proceeded to snap clean off (not even at a joint or nufin) which then jammed between the spokes a mudguard stay.
If any of you's fine people could provide any insight into why this could have happened t'would be great


James

 

[02GF74]

you are pedalling so the top part of the chain is going forwards and lower part going backwards into the rear mech.

something happened - chain popped a link so the side plate splayed out and was too wide to pass through the rear mech.

with the force you are applying, the chain pulls the rear mech back - either you are prevented from pedalling due to something jamming or as in almost all cases, the rear mech or the hanger for it snaps off. the bolt holding the mech is undercut i.e. weakened so it snaps off without damaging anything. a small twig if caught between chain and rear mech jockey wheel would cuase that too - no need to ask how I know that.

Once that has happened, the chain carries the mech up to the next place where it an jam: between wheel and rear stay or between seat tube and chain ring.

eventually you will be made to stop pedaling.

simples.

bad luck, these things happen once in a while, usually in the most inconvenient places and times plus it is always o nthe most expansive bike

 

[Mr Pig]

I've heard that some SRAM derailleurs are bad for that, for some reason they snag up and break off quite easily.

The key to avoiding things like this is regular checking and maintenance. Like any machine, if you don't look after your bike it'll let you down. I go out cycling with a bunch of other guys and it's the same ones who break down and have problems over and over again. One guy mentioned a clicking from his chain and when I looked at it one of the links was missing half of a side plate!

Keep everything tight, clean and well adjusted and you'll spend less time at the side of the road.