Chain jammed behind cassette shock!

[Jon C C on a Bianchi]

Hi, all

Sam somehow managed to shed his chain this morning and it got jammed between the cassette and the wheel. I couldn't get it out - tried everything. In the end had to abandon the ride. I cycled home - picked the car up and collected Sam and the bike.

Had to remove the cassette in the end to release the chain.

two things - what do you think caused the chain to jump off the cassette (gear changes seem absolutely fine) and has anyone had a chain jam this badly before and how did you sort it??

We were lucky today we were only 10 miles form home - don't want this to happen in the middle of nowhere.

thanks in anticipation

Jon

[Duncan T]

Have you got the end stops set up right? you shouldn't be able to take the cage any further into the wheel than the center of the largest cassette cog. [url]http://www.bikerepaironline.com/rear_derailleur_installation_and.htm[/url] describes how to do it about half way down the page in the 'Set the L Stop Limit Screw' section.

[Andrew G]

If the stops are adjusted correctly then it shouldn't happen, but still can. Very rare though. Check the cage is straight, if it has had a alight knock when being plonked up against something then it might have knocked it slightly, just give a gentle tweak to straighten it up.

If it does happen on the move you can often shift it by releasing the wheel, then straighten the rear mech/cage out with you hand and wiggle it about a bit. Ideally a two person job but you can often manipulate the chain free. Worst case scenario then you can split then chain (easy if you have a quick-link - eg.KMC) and that can often help free it up.

[Jon C C on a Bianchi]

thanks, fellas

It's odd. I can't really see anything wrong. the gears consistently change to the biggest sproket without jumping over board. i can't see a bend in the cage but don't really know what I'm looking for .


yeah, it was absolutely jammed. I couldn't even get the wheel out. Thought about splitting the chain (KMC quick link an' all) but couldn't see how to do it - something I'm going to have to learn how to do - and quick!

anyway, hopefully see you tomorrow morning, Andrew - GBs at NINE!!! aargh!

cheers

Jon

[Marek]

If you have a KMC quick link, and this part is not the part stuck behind the cassette, then you have to press the link together, thumb and forefinger pressing the link, then try to simultaneously push the links towards each other from the left and right. Hope that kinda makes sense, it is a bit fiddly, but is easier than using a chainbreaker.

Otherwise, just yank it and pull the bugger until it comes free, should do eventually, no upper body strength you cyclists, get the wife to do it.

Cheers

Marek....

[mrP(Boonen)VT]

You lot really should attend my Maintenance Master Class

Guru P

[Jon C C on a Bianchi]

[quote="Marek"]
Otherwise, just yank it and pull the bugger until it comes free, should do eventually, no upper body strength you cyclists, get the wife to do it.

Cheers

Marek....

[Jon C C on a Bianchi]

[quote="mrP(Boonen)VT"]You lot really should attend my Maintenance Master Class

Guru P

[Jon H]

[quote="mrP(Boonen)VT"]You lot really should attend my Maintenance Master Class

Guru P

[Snoop Doug]

[quote="mrP(Boonen)VT"]You lot really should attend my Maintenance Master Class

Guru P

[Andrew G]

Did anyone suggest splitting the chain on Sunday Jon? You could have nipped a section out and then used the shortened chain, Sam would just have had to stick to the smaller sprockets to get home, but would have been able to use all the chainrings so should have had enough gears.

[Antloony]

[quote="Andrew G"]Did anyone suggest splitting the chain on Sunday Jon? You could have nipped a section out and then used the shortened chain, Sam would just have had to stick to the smaller sprockets to get home, but would have been able to use all the chainrings so should have had enough gears.

[mrP(Boonen)VT]

Could have snipped a few spokes

[John the old'un]

[quote="mrP(Boonen)VT"]Could have snipped a few spokes

[Andrew G]

I don't have to mention the groupset do I?