Cool gear – episode I

Brice installing an odometer on his bike. The odometer is kind of a nifty gadget. One part, that includes a coil, attaches to the front fork, and a little magnet hooks to one of the front spokes. You tell the computer the diameter of your bike wheel, and, with the magic of physics, the computer senses how frequently the magnet passes by the coil and voila! Your speed and distance.