Broken derailleur and then some

[Sh4rkyBloke]

Traveling in this morning, all is well with the world...

Then my chain starts slipping a bit, jumping between gears... nothing too drastic so I continue thinking I'll take a look at it when I reach the office.

The jumping gets a little bit worse just as I'm approaching some traffic lights at a 90 degree right hand turn. I'm in the RH lane and think I'll pull over when I round the corner (i.e. out of the traffic).

Lights change and off I go... it can't seem to select a gear, jumping quite a bit more now and then suddenly the bike locks up completely. Slight panic as it skids to a halt, but no real danger as no-one is behind me (fortunately!)

Dismount and survey the damage...

Rear derailleur is bent backward and is meshed into the cassette, chain has snapped, bent a couple of links and is wedged between cassette and spokes (having completely shattered the spoke protector), and lower half of derailleur (jockey wheel and surrounding cage) have completely disintegrated/sheared off!!!! !

So - anyone got any ideas as to what the f*ck happened???

I'm thinking that there was some issue with the lower half of the derailleur which caused the skipping/jumping of the chain (the cable is still intact, btw) and then it broke which then caused all the other problems. Does this seem reasonable/possible?

The bike is less than 6 months old so I am assuming that it's some defective part (had some issues with the gears jumping when I bought it, but that seemed to have been resolved by some adjustment/wearing in).

I've contacted the shop and am awaiting a reply - just wondered what people thought.

 

[jayce]

it sounds like it was out of line the lower half for it too catch in the spokes and then in the cassette ,could you have caught it getting it in or out of the house or garage ,because slight jumping is either a stiff chain or mech out of line jumping off jockey wheels ,,or one of the jockey nuts could have come loose

 

[barq]

Oh bad luck. My only experience of something that bad was when I clipped a tree stump on my MTB and sent the derailleur into the spokes.

Do you know what gear you were in at the time? By which I mean approximately where on the cassette? I wonder if the derailleur limits were set wrongly. Any chance of a photo - it might make things clearer.

 

[spandex]

Yes your chain has snapped for some reason in doing so one of the broken bits of the chain caught on your R mech and ripped it back words. If it is just 6 months old take it back to them and tell them what happened. But if it looks like it is misuse or were/tear you will have to pay.

 

[Sh4rkyBloke]

it sounds like it was out of line the lower half for it too catch in the spokes and then in the cassette ,could you have caught it getting it in or out of the house or garage ,because slight jumping is either a stiff chain or mech out of line jumping off jockey wheels ,,or one of the jockey nuts could have come loose

Never been banged against anything (to my knowledge!) - I could possibly go for that if it was within the first few hundred yards, but this happened after 5+ miles and went from slight jumping/slipping to complete lockup in the space of about 200 - 300m.

I did a scout around before going home with a colleague (not literally, she just gave me a lift! ) and found the lower part of the derailleur and half the lower jockey wheel (tension pulley?) still inside the piece of cage that had sheared off!

I was in a mid cassette gear (I never use the bottom 2 or 3) as I was pulling away from the lights when it all happened - so no problems with it being due to shifting (I wasn't) or the limit screws being out.

It's a bloody mystery!

And yes, Lee, thanks - I do check my bike before each ride in terms of brakes working, tyres fully inflated, lights working, no play in steering and/or saddle... bit difficult to check rear mech each time though without riding it...

 

[jayce]

hope the lbs can give you some ideas fella to wot the f**k happened cause its a new bike and your probably fuming

 

[Joe24]

On a ride once, this guy on a very expensive bike(has dura ace on) had his chain snap as he was trying to race me to a sign while i was on my fixed.
Chain put back on, and he went off. He ended up in the chain gang, i got dropped, but wasnt far behind the group. Just coming up to the main road and his back wheel locks up.
The rear mech had bent inwards to the wheel, and locked the wheel up. He had a very very bent Dura Ace rear mech, and was pushed back to his work by someone else.
Not too sure what had happened, but he also put a very big flat spot on a Pro race 3 tyre.

 

[andy_wrx]

Sound like the chain broke.

Perhaps one of the sideplates of the chain gave way at the rivethole, the chain started to separate at the pin, went round several times, jumping, until it widened-out so far as to get stuck in the mech cage and as you continued pedalling the whole thing jammed up into the cassette.