My bmx bike crank makes popping noises than then chain falls off why?

the popping sound usually comes from the chain being overtightend in a certain spot because either the chainring is out of round,bent, or it has some very tight links in it. My suggestion is to replace the chainring and replace the chain both. If you are using a 1piece crank you will want to replace that to because it could be bent which would cause the chainring to sit out of line in the drive train also causing the same effect. If replacing the chainring and chain does not help then you need to check out if the drivetrain is in line aka the chainwheel in line with the freewheel. If they are not you may need to remove a spacer on the drive side if possible to help line them up better.

you need to have the bearings replaced
It pops when the chain and the sprocket are not aligned.
Check to be sure the sprocket is not bent or the chain kinked/defective.
Make sure the rear wheel is straight and the chain is tight.
your ball bearings arebad in the crank..take it off n put new ones in or try to re-grease old ones..
check the sprockets for broken teeth and replace the chain with a new one they do stretch out. also could be adjusted to loose

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Street Bike Exercise Bike Stationary Bike Recumbent Bike Bmx Bike Kids Bike Schwinn Bike Cruiser Bike Road Bike Folding Bike

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