Left crank Arm may get loose for any Bicycle after regular usage or if the nut got loose due to delivery vibration. It is common issue in all Bicycles with cotterless Square tapered sealed BB Set. The issue Might be resolved by changing the left arm only if you have not pedal the cycle in loose arm for long duration otherwise the inner material of both left crank and BB set wear out which causes issue in fixing the crank again.
Crank Arm length - 165/170cm depending on stock
Pair of left crank and Kenli square taper 123mm bottom bracket for repair purpose to resolve issues such as
- Left crank getting loose
- Not able to tighten the bolt and crank getting loose again
This is normal issue in all bicycle which you square tapered and can be fixed easily by replacing the parts