Shadow of a wheel

Opportunist shot today.

Riding the train to work and a guy with his mountain bike is sitting opposite me. I'm reading stuff on my iPhone and then I notice the shadow on the floor... thought it was a cool shot. But of course once I've decided to take the photo the train is going in and out of the sunshine so the shadow kept coming and going.... a few unlucky shots later I get one I like... add a few edits (normally don't like editing photos too much) and this is today's blip