why does my bike chain fall off?

[Jose]

my bike is a bmx and when im pedaling fast the chain just falls off,what do i do?

 

[imported_Serial Stunter]

It could what the other guy said. But it could also be a worn crank bearing. Check for any unusual play in the cranks system.

This will cause a misalignment of the front and rear sprockets causing the chain to skip a tooth and peel itself off.

Also check for damaged or ramped sprocket teeth.

 

[the pedestrian]

because your rear sprocket is not properly aligned with your drive sprocket, try playing with the rear wheel a little; i bet you will get it working properly

 

[magic sword]

you need to adjust the tension on the chain, get a bike shop to remove a link of the chain to see if it grips better....the shop should be able to fix it