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India
1 Posts

 Posted - 04/18/2014 :  14:24:14 HiI am working on a project where my problem statement is to "build a hybrid three wheeled vehicle (tadpole config and side by side seating) which is to be driven by two riders and may alternatively or simultaneously be driven by electrical power as well". I am currently working on the human powered drive - basically determining what gear ratios to work with and what torque ranges to expect. I have tried to find some text on this but I am unable to get some good useful info on the design. I am planning to transfer the power by both driver to a jackshaft and then back to the rear wheel from there. Can someone suggest me how to calculate the torque required to pedal the vehicle upto a desired speed. I am highly confused at this point of time and am running late due to this. SO please help. RegardsAbhimanyu Singh BhakuniBachelors in Engineering (Manufacturing Processes and Automation)University of Delhi, INDIA

USA
88 Posts

 Posted - 04/19/2014 :  13:42:01 Bicycles use the method of calculated gear inches, which is basically just the distance that a tire of a given diameter (in inches) would travel in one revolution. Another way to think of it is that if the chain ring and rear cog were the same size and your trike had a 20" rear tire, than one revolution of the cranks would advance your trike 20 gear inches or a distance of 20 X pi inches. (metric conversions necessary) . The selected gearing varies based on rider fitness and cycling experience, the terrain, and vehicle design. There are likely too many variable involved (CdA and Crr. etc.)to be able to calculate the torque required to reach a given speed with an untested design but it takes a strong rider to continually produce 1/2 hp. You can find usable estimates for rider power outputs and the other variable to determine a maximum estimated speed and then, using cadence, calculate the gear inches required to equal that speed and determine the gear ratios required in your design."it's important to understand what makes them fast. It's more important to understand what keeps them from going faster." DS

Sweden
3 Posts