Earth - Mountain Bike Trails - Episode 211



Slick Rock
In order to navigate Moab, your bike tires have to "grip" the rock. That requires friction. Do your own study of how well the rubber meets the road right in class. Get a board that can be used as a shelf, about 4 feet long and 1 foot wide (1.3 meters by 30 cm). Then get a rectangular rubber pencil eraser or even a hockey puck. Set the puck on one end of the board and slowly lift that end up, making a ramp. Keep lifting, until the puck first starts to slide. Measure the height or the angle of the ramp. Repeat the procedure, changing the surface of the ramp. Cover the ramp's surface with different materials such as sand paper or aluminum foil. How high do you tilt the ramp before the puck slides now? Find the surfaces that give the best and worst grip.