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Help - dropping chain


ozgti's picture

By ozgti - Posted on 15 January 2014

Hi there,

Last few rides my chain has been dropping from the middle chainring when I'm riding a rocky downhill section. I wasn't trying to change gears or even pedalling. Gear in the rear may be in the smallest 3 cogs. Other then that it seems to shift ok. What could be the reason for the chain dropping? worn chainring? checked the chain with a measuring thing and seems ok. Chain was changed maybe a year ago along with the inner chainring and cassette. haven't had any problem with the drive train till now.

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Jonathan's picture

Maybe your chain has stretched? Maybe try take out a link..

At least thats my .2 cents

Cheers,

Jono.

GAZZA's picture

Get it in the big dog to give a bit more tension on the chain when clattering down the bumpy stuff.

ChopStiR's picture

Was thinking the chain might be a link to long, not sure if that would effect the gear changes if that was the case.

MrSarcastic's picture

The front derailleur cage may have a slight bend in it??

Flynny's picture

Lots of options.

* front derailleur not quiet square with rings or incorrectly adjusted.

* chain too long. Make sure you have enough length before taking out a link
Rule of thumb is put it in big ring at front and big ring at back and make sure you have at least a link of slack left in the derailleur to account for chain growth through the suspension cycle.

that said I use to race DH on my old ac with triple ring up front and no chain guide. Tightened the chain up more so it was too tight to run big up from and 1-2-3 up back. You should never be that chain cross anyway just had to remember lung busting climb in XC races to change down the front first

* rear derailleur spring a little stretched so it's not supplying enough tension or B tensions not adjusted right

ozgti's picture

Thanks for the suggestions guys. Will check those out. So a worn chainring is not a potential cause? I thought maybe worn teeth is less able to hold the chain in place?

hawkeye's picture

Great advice from Flynny

From my experience the chain being too long is the most common culprit. For some reason most manufacturers seem to leave it at least one link pair too long. Getting it right the way Flynny described gets rid of 90% of the problem. I'd look there first.

The new generation of clutch derailleurs are a big improvement and I get almost zero chainslap on the Scalpel. I still change up to the big ring on fast rough descents though.

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