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Chain very unparallel at largest front gear+largest rear gear causing chain fall off

[ Edited ]
Hi all

I have recently bought a used Triban 500 flat bat bike road bike and noticed a problem. Basically when it's at the largest front gear (the one farthest from bike)+largest rear gear (the one closest to the wheel) combination, the chain is very un-parallel to the bike any more. As far as I have cycling with it, this doest not affect cycling or changing gears at all when normally pedalling forwards but when pushing or pedalling the bike backwords, the chain very likely (almost definately) comes off from the front largest gear and sometimes the chain gets stuck at front derailleur.

Is this a problem easy to be fixed? Because it's a second hand one so I don't have any sort of proof of purchase, in this case would decathlon willing to fix this? will it be a charge? The dearest decathlon store is about half an hour drive so if they will definitly charge me for fixing this I would rather get it to a local bike store.

Many thanks.
Sports Member

Re: Chain very unparallel at largest front gear+largest rear gear causing chain fall off

If you have the gears like that there is too much of an angle in the chain you should really change the chain on the front chain ring to the smaller one nearer the frame. This puts less pressure on the chain when it's on the larger gears on your wheel

Sports Member

Re: Chain very unparallel at largest front gear+largest rear gear causing chain fall off

[ Edited ]
 
Occasional Contributor

Re: Chain very unparallel at largest front gear+largest rear gear causing chain fall off

Hi @henrybham

 

What you are experiencing is a problem called cross-chaining.  This is caused by either the bike being in 1st gear rear and big ring at the front and also 7th gear rear and small ring at the front.

 

Most of this can be dialled out with a little time but because of the triple rings at the front you will never completely remove all of the rubbing.

 

Your local Decathlon Workshop should be able to help.

 

Any further questions please do not hesitate to ask.

Craig
Workshop Technician
Decathlon Coventry
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