Last night my rear mech hanger broke, and not sure why, came out of the blue, on a climb though. My cassette was a bit worn out and I was running with a chain shorther than usual. Could it be the reason(s)? Just order 2 new rear mech hangers, as a spare sounds a very good idea to carry it with you.

Gilles

It was already fatally damaged from a previous crash?

[video]http://www.youtube.com/watch?v=vp1HVg_J7QA[/video]

Impossible to know what causes this, I’ve seen it on perfectly adjusted set-ups.

Odd coincidence Gilles but Mick smashed his up last night in the Wyre as well (taking a 6 week old XT mech with it!).

Not a happy bunny and he had to walk all the way back to the Duke from the far side.

I’d suggest a brand new bike rather than replacing the gear hanger….

Steve, yes I saw that on Endomondo! Weird. I did spend 30 min converting my bike to singlespeed, and ride bike home at very slow pace.

Learnt my lesson last year when my hanger broke in the middle of a ride. Always carry a spare one in my pack now. Good job I do aswell- rear mech sheared off last Sunday doing a route round the lakes. Half an hour later we were on our merry way again.

Mick tried to convert his to SS Gilles but it just wouldn’t work so he gave up and walked instead.

“I was running with a chain shorther than usual”

that could the problem, are you riding a bouncy frame? A single pivot bouncy frame (any that needs chain growth)

If you reach a point where the chain is against the stops (big at theback and mid to big at the front) the rear mech will be acting as a lever on the hanger, and they are made to break.
I’d make sure you have the right chain length.

And why don’t shops sell spare hangers with new bikes/frames?

Maybe you hit an errant pork scratching 😀

too short chain + wrong gear combo
debris in chain causing it to foul
dodgy link in chain
crash damage on hanger

Probably more causes to, mine went on a road bike at 5mph, hadn’t been crashed and I wasn’t changing gear at the time. I could hear a slight rattling from the drive chain but assumed the gear cable had stretched a bit (new bike) so just needed a bit of fettling, I’m thinking now maybe a link and gone causing the rattling then eventually jammed resulting in the mech shearing off.

yes, I’m riding a superlight, so single pivot and bouncing a lot. Looks like that could be a good reason.

No errant pork scratching in Wilsthire, as well as the badgers, they all have been killed by the farmers.

“so single pivot and bouncing a lot” with a shorten chain, that would do it.

Also worth checking that your multitool fits the spare mech hanger, you’ll still have a long walk if it doesn’t.

http://www.paragonmachineworks.com/images/pdfs/faqhangers.pdf

“What’s the difference between a 6061 aluminum hanger and a 7075
aluminum hanger and which material should I choose?
6061 hangers are more ductile than 7075 hangers but do not have 7075’s
tensile strength. A 6061 hanger will bend before it breaks. A 7075 hanger
will take a bigger hit than the 6061 but will fail catastrophically. In either case it is advisable to keep a spare with your bike.”

“so single pivot and bouncing a lot” with a shorten chain, that would do it.

I would put it down to rider weight myself!!