Chain jumping off

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2009-08-09 5:27 PM

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Subject: Chain jumping off
Hi everyone,

Brought a brand new bike a few weeks ago, and have been having trouble with the chain jumping off when the pedals are going backwards. The problem is that this happens when back pedaling to get the pedals in the correct position to take off. It also happens if I have to move the bike backwards a little to maneuver it out of the garage.

It had its first service a couple of days ago and I mentioned it to the mechanic, but the problem is still happening.

Any ideas? I realize they're not really designed to go backwards, but seems ridiculous that this happens with even a little movement.

Thanks in advance,
Jarred 

2009-08-09 11:03 PM
in reply to: #2337156

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Subject: RE: Chain jumping off
Just read that this could be due to cross chaining - I normally ride along the flats in the biggest chain ring and the biggest cog on the back. Should I do otherwise?
2009-08-09 11:39 PM
in reply to: #2337156

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Subject: RE: Chain jumping off
Yes-do otherwise.  Big-Big/Small-small combos are not good.  (big ring-big rear cog etc).  Your chain really works better when it travels in a straight line;  big-big (or small-small)combos tend to bend (deflect) the chain sideways a bit. 
You're basically telling your bike "I want a BIG gear (fast) in front but a small gear (slow) in the back.  The bike is confused, so it 'reminds' you by making a lot of noise and acting funny.   
2009-08-10 12:27 AM
in reply to: #2337156

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Subject: RE: Chain jumping off
As jeffnboise already pointed out, it's probably due to crosschaining that you are dropping the chain; which means that you need to learn how to shift properly. A basic rule should be that for the big ring, you can't use the two biggest cogs in the back, and for the small ring, you can't use the two smallest cogs in the back.

Also, you might need to clean and relube the chain. Quite often on new bikes, the chain has a protective coating on it (so it doesn't rust), but that isn't really a lubrication, which means that you end up with a stiffer chain that will jump much easier.
2009-08-10 6:47 AM
in reply to: #2337804

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Subject: RE: Chain jumping off
audiojan - 2009-08-10 1:27 AM As jeffnboise already pointed out, it's probably due to crosschaining that you are dropping the chain; which means that you need to learn how to shift properly. A basic rule should be that for the big ring, you can't shouldn't use the two biggest cogs in the back, and for the small ring, you can't shouldn't use the two smallest cogs in the back. Also, you might need to clean and relube the chain. Quite often on new bikes, the chain has a protective coating on it (so it doesn't rust), but that isn't really a lubrication, which means that you end up with a stiffer chain that will jump much easier.


It's not that you can't, really.  It's just you will have a happier bike if you don't.  But for short periods, it should be fine.  Just not as a starting point for the gearing.  Keep in mind that if you are running on the biggest cassette in the back, you can get the same gearing resistance with the smaller chainring in front and going up 3 or 4 cogs in the back.
2009-08-10 4:49 PM
in reply to: #2337156

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Subject: RE: Chain jumping off
Awesome, thanks very much for the answers. Next ride will definitely start using the smaller chainring more, should fix it. This should also remove the problem of having to change chainrings in hilly areas.

Thanks again,
Jarred. 

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