What Formulas are Needed to Calculate Rotational Force and Power for an Electric Bicycle Motor?

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SUMMARY

This discussion focuses on the calculations required to determine the rotational force and power needed for an electric bicycle motor. Key formulas include those for torque, watts, and horsepower, which are essential for calculating the wattage necessary to turn the wheel while carrying a 200 lb rider. A physically fit human can sustain approximately 200 watts, which serves as a benchmark for the motor's power output. Understanding these calculations is crucial for designing an effective electric motor for bicycles.

PREREQUISITES
  • Understanding of torque calculations
  • Knowledge of power output measurements (watts, horsepower)
  • Familiarity with rotational motion principles
  • Basic physics of forces and motion
NEXT STEPS
  • Research the formulas for calculating torque in rotational systems
  • Learn about the relationship between power, torque, and rotational speed
  • Explore electric motor specifications and efficiency ratings
  • Investigate human power output comparisons for electric motor design
USEFUL FOR

This discussion is beneficial for hobbyists designing electric bicycles, engineers working on electric motor specifications, and anyone interested in the physics of motion and power in cycling applications.

aliaze1
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Hello everyone,

My brother and I are designing an electric motor for a bicycle (just for fun). Assuming a 200 lb person rides the bike, there is a normal force on each wheel of 100 lbs. We forgot the formulas related to rotational motion and power (watts, horsepower, torque) for this situation (finding the wattage required to turn the wheel at a certain rate carrying a person of that weight). Thanks!
 
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aliaze1 said:
Hello everyone,

My brother and I are designing an electric motor for a bicycle (just for fun). Assuming a 200 lb person rides the bike, there is a normal force on each wheel of 100 lbs. We forgot the formulas related to rotational motion and power (watts, horsepower, torque) for this situation (finding the wattage required to turn the wheel at a certain rate carrying a person of that weight). Thanks!
The normal force is not really an issue.

If you want it to duplicate the power output of a human, you will need an electric motor that will have a power output similar to a human. A physically fit human can produce about 200 watts on a sustained basis and much more in a sprint. See: http://en.wikipedia.org/wiki/Human-powered_transport

AM
 

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