Chain tight and loose

[Hurricane09]

Hello,

My son's BMX recently ran into an issue where the chain is too tight and loose at the same time - as I pedal it will go tight/loose/tight/loose. What things should I check for to troubleshoot the issue?

Thanks,
Bob.

[xerxes]

Sounds like you may have a stiff link.

Take a look here: http://bikeride.com/stiff-chain-link/

[Hurricane09]

I'll take a look tonight after work and post back - thanks alot!

[DaveM]

Something is out of round, either the front chainring or less likely the freewheel. Check that the front chainring is not bent or wobbling. Even if it's not, it may not be perfectly centered on the axle which will cause this. A little tight/loose is ok, but too much and you'll start having the chain fall off.

[X-RAY]

make sure the wheel is square in the dropouts also.

[Bill]

Also I came into a BMX that had a chain that was "bent" and stretched from playing around on the ramps! Now as said above the front chain ring was bent too.

[JohnnyCO]

Check out the front ring to see if its bent. Bottom bracket bent?

[X-RAY]

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[JonB]

Bent wheel axle is another possible culprit.

When your son uses his BMX does he just ride around or does he huck off stuff, jump tables and ramps, etc.

If he came up short and cased something it's entirely possible his wheel was damaged, or simply from doing a big drop to flat concrete puts a lot of stress onto the wheels and axles. He might have possibly bent his cranks/bb axle from doing something like this as well (more likely)