The freewheeler

The physical training instructor was drilling a platoon of soldiers.

“I want every man to lie on his back, put his legs in the air and
move them as though he were riding a bicycle,” he explained.
“Now begin!”

After a few minutes, one of the men stopped.

“Why did you stop. Smith?” demanded the officer.

“If you please, sir,” said Smith, “I’m freewheeling for a while.”