but as Prof Bunzen points out the single key release if installed correctly should not be causing his crank to come loose.
the OP needs to remove his cranks, clean the spindle and the crank then reinstall and torque.
Never ride a bike with loose cranks. they can be easily damaged.
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“One morning you wake up, the girl is gone, the bikes are gone, all that's left behind is a pair of old tires and a tube of tubular glue, all squeezed out"
Sugar "Kane" Kowalczyk