Why does my bike chain keep loosening up?
A motorcycle chain that keeps getting loose is usually caused by the rear axle or chain tensioning bolts not being tight enough. It can also be cause by a new chain not being worn in enough, worn down sprocket teeth, having too tight of a tension, or having the wrong size of chain installed.
Why is my chain really loose?
Your chain might simply be too old or can stretch over time. When this occurs you need to replace it. Consider that your loose chain also may be due to operator error. Exceeding the recommended gear range for the rear derailleur on your bike may lead to a droopy chain when you ride in these gears.
What happens if motorbike chain is loose?
#1 Chain skipping over the teeth
If the chain is too slack, it can skip over the tooth in the sprockets, This skipping over of teeth leads to uneven transmission of power from the engine to the wheel. As a result, the speed of the motorcycle will unevenly oscillate without any intervention from the rider.