Determining the Fastest Gear Set-Up on a Single Speed BMX Bike through a Designated Course

Overview

Objectives/Goals The objective of my project is to determine the best gear combinations and crank arm lengths for a single speed BMX race bike on a designated course. Methods/Materials A 2006 Redman Expert XL BMX Racing Frame with 20" wheels was used with 6 different gear set-ups with 160mm and 165mm crank arms. A testing course was selected on an American Bicycle Association Sanctioned Track and measured with a measuring wheel. Using a hydrraulic strating gate and a line and cones marking the finishing point, I tested the different gear set-ups using a stop-watch to track the results. I rested during each gear change as to be sure that fatigue would not effect the results. Results After running several tests on the designated course, I recorded my results on a chart. The smaller front chain ring and rear cogs with the 165mm crank arms proved to be the fastest combinations. Conclusions/Discussion After testing the gear combinations, I realized that the 37 front chain ring gear with a 13 rear gear using the 165mm crank arms produces the fastest average time on the first straight of Tulare BMX track. This set-up had the perfect resistance against my feet at top end speed and surprisingly did not take that much effort to get moving. The slowest set-up was the 43 front chain ring gear with a 16 rear gear using the 165mm crank arms. This set-up was the easiest to get going because of the torque it produces during the start. However, the gear had lost all resistance against my feet at top speed.

Competition history

• CSEF 2007 Applied Mechanics & Structures · Entry J0214

Resources

• CSEF project summary ↗

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