Chain keeps coming off GIANT bike. Please help.

SoJo

New Member
Hi, I have recently purchased a Giant Fathom e and have a problem as the chain keeps coming off when i stop.
If i keep peddling it doesn’t come off. Has anyone else had this problem or does anyone know what causes this.
 

Browneye

Well-Known Member
Front or rear chain rings?
The front has a guide, not sure how it could come off there.
If it's jumping cassette gears you likely need a derailleur adjustment. Very easy to do, or take to your shop.
 

SoJo

New Member
Front or rear chain rings?
The front has a guide, not sure how it could come off there.
If it's jumping cassette gears you likely need a derailleur adjustment. Very easy to do, or take to your shop.
It’s coming off the front chainring. It doesn’t seem to have a guide. Should it have one?
 

Browneye

Well-Known Member
Does it have a derailleur clutch? If so, is it engaged?
I admit that I don’t know every detail of every bike. ;)
EDIT: Spec says it has Deore 9 shadow - I’m pretty sure there’s no clutch on that one.
I wonder if there’s a failure in the components. Has it been dropped or crashed?
Does it come off in all gears? Or just on the smallest rear gears?
How many total miles/km’s? Chain stretch??
 
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Sierratim

Well-Known Member
It’s coming off the front chainring. It doesn’t seem to have a guide. Should it have one?
Sounds like a newer bike so chain wear shouldn't be an issue.

With a single front chain ring, this bike is most likely equipped with a narrow-wide chain ring. Lacking a front derailleur, these are designed to help keep the chain from dropping off the chain ring. The chain does need to be installed correctly, i.e. the narrowest chain links need to match their intended teeth. If the chain is installed 1/2 link off it will be much more prone to being dropped. On our Specialized bikes the rings have a graphic to help guide the chain onto the correct teeth. For the Vados we ride, this puts the widest teeth (measured at their base) in the narrowest chain links. Other online resources instruct that the widest teeth should match the widest chain link, but not so for the Vado. Haven't dropped a chain on either bike in over a year of ownership.
 

Nova Haibike

Well-Known Member
One possibility is that the cassette freehub is not functioning properly, or something (such as a broken spoke protector) ir preventing the cassette from freewheeling. When you stop pedaling, the chain should stop moving as well. If it continues to move, the chain is under no tension at all. Because of the lack of tension, even with a narrow wide chainring the chain could derail.