Mountainboarding by Sean, Ben and Neil

A mountainboard is a kind of skateboard on steroids. The decks are big, the wheels are rubber, and your feet fit into bindings. When we mountainboard in Southern California, we notice that our boards ride differently when the tire pressure is higher or lower. Sometimes the wrong pressure makes us feel out of control. Our question: Which tire pressure will let us maintain speed and control through turns?

What did we do?
We set up a minicourse, and rode it at three different tire pressures: 10 psi, 25 psi, and 60 psi (or pounds per square inch). The more psi, the harder the tire; the less psi, the squishier. We recorded the time to complete the course, and reported how much control we had.

What did we find out?
The lowest tire pressure gave us our slowest times, but good control. The medium pressure allowed the board to go faster, but we felt we had less control. To our surprise, the highest pressure did not give us our fastest run, probably because we felt completely out of control. It was obvious that tire pressure really does make a difference, and that you have to choose the pressure that matches the kind of ride you want to have.

What can you do?

• Design a test to find out what tire pressure is best for performing bike stunts. Is it better to have mushy tires, or hard ones? Does it depend on the trick, or the style of riding?
   
  
• Mountainboards coast, but what kind of tire pressure do you want in a mountain bike that has to climb a hill, not coast? Is there a difference between coasting and climbing, as far as tire pressure choice? Design an investigation to find out.
   
  
• Come up with a way to measure your bike's "footprint," that is, how much tire touches the ground when the bike is standing still. How does the size of the footprint change when you are sitting on the bike, compared to when you aren't? How does the size of the footprint change with different tire pressures?
   
  
• Use this extreme sports investigation as a science fair project idea for your elementary or middle school science fair! Then tell us about it!
   
  

	Go to the DFTV Boards, and tell us about your science investigation.