Does a Bicycle Require Less Torque to Maintain Speed Than to Start Moving?

In summary, when starting a bicycle at rest and in the lowest gear, the applied torque on the rear wheel is equal to the ground frictional torque. However, once the bike is in motion, only the friction and air resistance need to be overcome, resulting in a lower torque requirement. This is why pedaling may feel easier once the bike is in motion and why pedaling must be maintained to prevent the bike from coming to a stop due to friction in the bearings, ground, and tires.
  • #1
fisico30
374
0
Hello Forum,

let say we are on a bicycle at rest and in the lowest gear. We start pedaling and the bike moves. The applied torque on the rear wheel is equal the ground frictional torque and the bike moves forward by action reaction...

Once we reach a certain speed on the bike, is the torque that we need to continue to apply the same as the torque we needed to apply to set the bicycle into motion or less?
It feels like it would be less but I am not sure why?

We surely need to keep on pedaling, otherwise the friction in the bearings, ground/tires would bring us to a stop.

thanks
fisico30
 
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  • #2
When you start you are overcoming friction as well as air resistance AND providing an additional acceleration, once in motion only the first two are required so less force is needed.
 

1. What is a bicycle's applied torque?

A bicycle's applied torque is the force that is exerted on the pedals by the rider in order to propel the bicycle forward. It is measured in units of Newton-meters (Nm) and is a product of the force applied and the distance from the axis of rotation.

2. How is torque applied in a bicycle?

Torque is applied in a bicycle through the use of pedals. When the rider pushes down on the pedals, they apply a force that turns the crank arm, which in turn rotates the chain and rear wheel, propelling the bicycle forward.

3. What is the relationship between applied torque and speed in a bicycle?

The relationship between applied torque and speed in a bicycle is known as the power-speed relationship. This means that the faster a rider pedals, the more torque they need to apply in order to maintain or increase their speed. This relationship is also affected by factors such as gear ratio, aerodynamics, and road conditions.

4. How does gear ratio affect applied torque in a bicycle?

Gear ratio refers to the ratio of the number of teeth on the front chainring to the number of teeth on the rear cassette. A higher gear ratio (i.e. more teeth on the front chainring) means that the rider will need to apply more torque in order to turn the pedals and maintain their speed. Conversely, a lower gear ratio requires less torque but results in a slower speed.

5. How does weight affect the applied torque in a bicycle?

Weight can have a significant impact on the amount of torque a rider needs to apply in order to move the bicycle forward. A heavier bicycle or rider will require more torque to accelerate and maintain a certain speed, while a lighter bicycle and rider will require less torque. This is why cyclists often try to reduce the weight of their equipment in order to improve their performance.

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