Design And Optimization Of An Integrated Gear Selector For Mountain Bikes
Ben Mann, M.S. University of Utah, December 2005
Mountain bikes are equipped with up to 27 gears. However, not all available gears
have useful gear rations and some of the gears result in increased wear through
extreme chain positions. Another fundamental flaw is the need for separate actuators
for the front and rear derailleurs, which makes it essentially impossible to
shift gears in the correct order to achieve a gradually increase or decrease
in gear ratio.
This project combines the shifters for the front and rear derailleur into a single
unit that can be operated either with the right or left hand. The unit uses an
internal cam system that is programmed in such a way that actuating the device
in one direction will gradually increase the gear ratio and reversing the direction
will gradually decrease the gear ratio. The unit also will avoid wear intense
chain positions and eliminate gears with identical or near-identical gear ratios.