Bicycle AerodynamicsBicycle Aerodynamics

byS.E. Cossey

Mr. Cosseyperiod x

September 20, 2000

Title: Quest for SpeedPurpose: To determine if lowering your body position while

going downhill on a bicycle can actually improve your speed

Which is faster?

upright or tucked

Hypothesis: A rider coasting downhill in a tucked position will reach a higher speed than if the rider remained upright

Materials: A long hill,(@300 yards) a bicycle, a timer, a bike, start and finish markers and a rider(with helmet)

Independent Variable: the rider’s body position on the bicycle (upright or crouched)

Dependent Variable: the time it takes to go down the hill

Constants: use same bike, same rider , follow same path, run all trials on the same day, hold same body

position

Control: Compare course times for the upright position with the times for the crouched position

Procedure: Mark the start and finish points for the course. From a still position lift foot and begin descent. Start timer the instant foot is off the ground. Follow same path down the course. Maintain same body position (either upright or tucked) for entire length of course. Stop timer the instant the end point is passed. Record data.

Data:Data:

Trial 1 (seconds)

Trial 2 (seconds)

Trial 3 (seconds)

Average (seconds)

Times for upright position

43.21 41.85 42.43 42.496

Times for crouched position

40.8 40.36 39.9 40.353

38.038.539.039.540.040.541.041.542.042.543.043.5

Upright

Crouched

Conclusion:Conclusion:

The data I collected supports my hypothesis that an aerodynamic body position will help increase downhill speed on a bicycle. On average my rider finished the course a full 2 seconds faster while in a crouched position.

How come this rider was not allowed to do some of the trial runs in the experiment? List as many reasons as you can.