# Chain keeps popping off when pedaling



## JeanBaptiseClamence (Feb 16, 2012)

I've got an old school Cannondale and the other day I was out riding in the desert and the chain popped off... I put the chain back on, but then it kept popping off. I was able to actually get back to my vehicle and I took it to the bike store the guy said it was fine but then when I went out today it immediately started popping off again. At the bike store he put the bike up on the suspension rack and pedaled and shifted gears and everything was fine, but when I put pressure and actually ride it's just popping off. Sorry, maybe this is vague but since I'm kind of a newb I don't have a lot of the terminology down. Any suggestions? Maybe a bent sproket?


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## DIRTJUNKIE (Oct 18, 2000)

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## qbert2000 (Jul 30, 2008)

sounds like a worn out drivetrain. how it shifts under no load doesn't test the wear. did your lbs measure the chain stretch? sadly, once it gets to this point (skipping) it's usually too late to just put on a new chain. chances are the chainrings and cassette are worn out too


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## Caffeine Powered (Mar 31, 2005)

qbert2000 said:


> sounds like a worn out drivetrain. how it shifts under no load doesn't test the wear. did your lbs measure the chain stretch? sadly, once it gets to this point (skipping) it's usually too late to just put on a new chain. chances are the chainrings and cassette are worn out too


^^this. I can't believe the "mechanic" missed it based on the description you gave. You should find a different LBS too.


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## Angryhalfling (Oct 8, 2011)

Caffeine Powered said:


> ^^this. I can't believe the "mechanic" missed it based on the description you gave. You should find a different LBS too.


For a start this. These sort of things should be absolute bread and butter of any lbs.


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## kdc1956 (Feb 5, 2010)

Sounds like you need a new LBS and a new bike to ride or you need to replace the drivetrain on it I do do the new bike route my self.


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## kapusta (Jan 17, 2004)

JeanBaptiseClamence said:


> I've got an old school Cannondale and the other day I was out riding in the desert and the chain popped off... I put the chain back on, but then it kept popping off. I was able to actually get back to my vehicle and I took it to the bike store the guy said it was fine but then when I went out today it immediately started popping off again. At the bike store he put the bike up on the suspension rack and pedaled and shifted gears and everything was fine, but when I put pressure and actually ride it's just popping off. Sorry, maybe this is vague but since I'm kind of a newb I don't have a lot of the terminology down. Any suggestions? Maybe a bent sproket?


How old are the chain, cassette, and rings?


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## JeanBaptiseClamence (Feb 16, 2012)

Thanks for the responses.... yeah, I was kinda surprised too. He said "oh, it's fine" and he put some oil on the chain and that was about it. The bike itself is a 1980s Cannondale, probably around '86 so I'm assuming the parts are the original parts on the bike. It was my dad's bike and he bought it new, never actually rode it, and gave it to me about five years ago.


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## kapusta (Jan 17, 2004)

JeanBaptiseClamence said:


> Thanks for the responses.... yeah, I was kinda surprised too. He said "oh, it's fine" and he put some oil on the chain and that was about it. The bike itself is a 1980s Cannondale, probably around '86 so I'm assuming the parts are the original parts on the bike. It was my dad's bike and he bought it new, never actually rode it, and gave it to me about five years ago.


So it is really old, but not much wear?

First check the chain for stretch (go to the Park tool site for explanations of this and how to check, it is really easy).

If it is stretched too much, replace the chain, and if it still skips, you will need to replace the rear cassette. You might want to replace the cassette anyway (if the chain is too stretched), they are not expensive for what you will need on that bike.

If the chain is not stretched, is it still in good shape? If not (or in doubt) replace it.

Also, while this is not the common cause of the skipping issue you are describing (especially since it is OK on the shop stand), it could still be worth your while to replace the shifter cables and housing, as really old cables and housing can cause some shifting issues.


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## JeanBaptiseClamence (Feb 16, 2012)

kapusta said:


> So it is really old, but not much wear?
> 
> First check the chain for stretch (go to the Park tool site for explanations of this and how to check, it is really easy).
> 
> ...


One of the shifter cable mounts actually broke off the main part of the frame and I duct taped it back on 

How much, would you say, it would cost to replace these parts? The reason I ask is because I'm buying a full suspension Rocky Mountain from my brother and I'd honestly rather put the money toward that. I was riding the Cannondale until I got a new bike and I'm hoping to have the Rocky Mountain in a few weeks (if I'm lucky - getting my brother to actually box it up and send it to me has proven to be an issue :madman

Oh, yes - the bike is super old but when my dad sent it to me it was pretty much in mint condition. He replaced the old rims and put new tires on it. Prior to me getting the bike I'd say my dad rode it maybe 50 times. :crazy:


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## kapusta (Jan 17, 2004)

JeanBaptiseClamence said:


> One of the shifter cable mounts actually broke off the main part of the frame and I duct taped it back on
> 
> How much, would you say, it would cost to replace these parts? The reason I ask is because I'm buying a full suspension Rocky Mountain from my brother and I'd honestly rather put the money toward that. I was riding the Cannondale until I got a new bike and I'm hoping to have the Rocky Mountain in a few weeks (if I'm lucky - getting my brother to actually box it up and send it to me has proven to be an issue :madman
> 
> Oh, yes - the bike is super old but when my dad sent it to me it was pretty much in mint condition. He replaced the old rims and put new tires on it. Prior to me getting the bike I'd say my dad rode it maybe 50 times. :crazy:


Chain: ~$15 (from the sounds of it you are unlikely to need a cassette) maybe less.

Cables and housing: ~$15. Though I'd just do the chain if it is needed, and leave the cables/housing if it is shifting OK and you are only riding it for a few more weeks.


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## bikerjohn64 (Feb 12, 2012)

You should be able to find a "band-type" cable stopper at your LBS to fix the original broken cable stops.


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## AndrwSwitch (Nov 8, 2007)

It's nice of everybody to suggest solutions, but I think you could stand to be more specific about the problem.

Is it coming off the crank or the cassette? Only off of one gear, or off of a few different ones? Skipping?

IME, when a bike throws a chain it's usually that the drivetrain isn't set up right. Wear doesn't help, certainly...


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## theMeat (Jan 5, 2010)

JeanBaptiseClamence said:


> One of the shifter cable mounts actually broke off the main part of the frame and I duct taped it back on


Think it's safe to say, from any stand point, that this should be addressed and my be the only issue.


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## kapusta (Jan 17, 2004)

theMeat said:


> Think it's safe to say, from any stand point, that this should be addressed and my be the only issue.


Good point:thumbsup:


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## ghoti (Mar 23, 2011)

The chain coming off is quite a different problem than skipping. Perhaps it's overshifting. Does it come off when you shift gears, which end of the chain comes off, the gears at the rear wheel, (cassette) or by the pedals, (chainrings)?


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## xenon (Apr 16, 2007)

If the chain comes off under load, it sounds like a bent chainring/broken tooth. Easy to check, if the chainring is just bent with teeth intact, you may true it with a vice grip.
If the chain pops under load without coming off, and it started suddenly, rather than developed over some while, it may be chainsuck, due to a worn out chainring (happens mostly with the middle ring). Then you may try to unscrew the ring and bolt it back up at right angle in relation to its current position. Takes little time, no need to pull the crank off. The trick doesn't always help, but is worth trying, I think.


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## Caffeine Powered (Mar 31, 2005)

a 1980's Cannondale? Holy Carp. I was selling them back then. The cable stops were plastic and were coming off even when they were new.An older Cannondale dealer will have a divided parts box with replacement cable guides and stops. Eventually C'dale started welding aluminum stops on the frame. While it's a solid frame and fork, the drive train parts have seen better days.

It could be as simple as looking at the limit screws on the front and rear deraileurs. If it's a cassette rear hub, the lock ring/lock cog could be loose. The rear deraileur may be bent or have significant play at its pivot pins. The front deraileur cage may have had the chain wear through (this is more common than you think) either the inboard or outboard guide portion. If intact, the front deraileur might be out of proper position (pivoted L/R or too high) .

The chain could be several years old. Most chains on MTBS that see frequent use are lucky to survive more than a year. Chances are the chain and cassette/freewheel are in need of replacement unless they were done recently. The chainrings on the crank might need replacing too. Look to see if the teeth are shaped like the fin on a shark. Don't be alarmed if a few are shaped this way on newer chainrings, this is a design feature to provide better up-shifts, but on older chainrings all the teeth uniformly wear and all the teeth will resemble the fin, not just a few.

This could begin to get expensive. you could easily be at $100 in parts in seconds, more if the deraileurs and shifters need replacement. 

I would do this... Buy a new bike as you mentioned. Keep the Cannondale as a project bike. Get an estimate of what needs to be done. As money and time allows replace what needs replacing. Do it yourself if you can. You'll save on labor and gain proficiency.


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## AndrwSwitch (Nov 8, 2007)

LOL, I looked to see if the poster provided any more details and missed the one where a cable guide was broken.

You need something like this.
Soma CABLE GUIDES/STOPS 31.8 STAINLESS HOUSING CLIP on eBay!

You may also find one in a small parts bin at a LBS. I haven't had good luck looking for them, but that doesn't necessarily mean you won't.


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## ForrestJones (May 25, 2009)

Caffeine Powered said:


> a 1980's Cannondale? Holy Carp. I was selling them back then. The cable stops were plastic and were coming off even when they were new.An older Cannondale dealer will have a divided parts box with replacement cable guides and stops. Eventually C'dale started welding aluminum stops on the frame. While it's a solid frame and fork, the drive train parts have seen better days.
> 
> It could be as simple as looking at the limit screws on the front and rear deraileurs. If it's a cassette rear hub, the lock ring/lock cog could be loose. The rear deraileur may be bent or have significant play at its pivot pins. The front deraileur cage may have had the chain wear through (this is more common than you think) either the inboard or outboard guide portion. If intact, the front deraileur might be out of proper position (pivoted L/R or too high) .
> 
> ...


Good advise all around. Might be just a deraileur adjustment, which you can DIY. The Rocky Mt can be your primary, the C-dale the beater bike you loan out to friends, once you get er up and running.


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## DIRTJUNKIE (Oct 18, 2000)

JeanBaptiseClamence said:


> One of the shifter cable mounts actually broke off the main part of the frame and I duct taped it back on
> 
> How much, would you say, it would cost to replace these parts? The reason I ask is because I'm buying a full suspension Rocky Mountain from my brother and I'd honestly rather put the money toward that. I was riding the Cannondale until I got a new bike and I'm hoping to have the Rocky Mountain in a few weeks *This>*(if I'm lucky - getting my brother to actually box it up and send it to me has proven to be an issue :madman
> 
> Oh, yes - the bike is super old but when my dad sent it to me it was pretty much in mint condition. He replaced the old rims and put new tires on it. Prior to me getting the bike I'd say my dad rode it maybe 50 times. :crazy:


Looks like your biggest problem I highlighted in bold.


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