I spent a few hours today competing in a gravity race somewhere in the depths of the English countryside. Film of my first run is here:

http://www.youtube.com/watch?v=qaBgB9jFRrc&feature=youtu.be

There's a canister of yellow smoke on the back and the kart has utterly rubbish brakes, I hit them straight after the finish line, you can hear me laughing at how completely inadequate they were!

I was wearing one of my Montreals:

Here's the kart (front left), made from wood and card, with string steering (hence the gloves in the watch photo) and two small blocks of wood for brakes (front brakes are for girls).