Rear Wheel Friction: Cycling on an Incline

In summary, in both cases of a cycle moving down an incline plane, the direction of friction on the rear wheel depends on whether the cycle is being pedalled or not. When the cycle is pedalled, the friction on the rear wheel is in the forward direction, pushing the cycle forward. When the cycle is not pedalled, there is a small backwards friction force on the rear wheel to keep it turning and prevent slipping. This is due to the small frictional torque opposing the turning of the wheel. Overall, the direction of friction on the rear wheel is dependent on the relative motion between surfaces.
  • #1
paras02
31
0
1. Pls tell me the direction of friction on the rear wheel of a cycle moving down on an incline plane in both the cases that are when cycle is being paddled and without any paddling ?
 
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  • #2
Is the cycle moving without any pedalling
 
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  • #3
paras02 said:
1. Pls tell me the direction of friction on the rear wheel of a cycle moving down on an incline plane in both the cases that are when cycle is being paddled and without any paddling ?

What is your answer to this question if there is no incline?
 
  • #4
Chestermiller said:
What is your answer to this question if there is no incline?
when pedalling in forward and when not pedalling in backward
 
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  • #5
Paddling is moving a boat using a paddle.

A bicycle is moved by turning it's pedals so the word is pedalling.
 
  • #6
Oops sorry
 
  • #7
Since we're dealing with words... The word is its, in the context of its pedals! There should be no apostrophe, either in English English or in American English.

I think you can get a good intuitive feel for the forces on the wheel by imagining that you're riding the bike on layers of paper which can slide over each other if the tangential stress is above a certain value. If you're pedalling the bike hard and the paper starts to slip, it will slip backwards - visualise it or try it - because of the frictional force from the back tyre (tire). So the paper (or, without paper, the road surface) will exert a forward force on the tyre (Newton's Third Law). This is the force that accelerates the bike, or, if moving at a steady speed, balances the backwards force of air resistance on the bike.

But (you might argue) doesn't friction always oppose motion? Not exactly. It opposes relative motion between surfaces. The bottom of the back tyre is trying to slip backwards on the road, when you're pedalling. The frictional force on the bottom of the back tyre is therefore forwards.

When you're not pedalling there is a small backwards force from the road acting on the bottom of the tyre. To understand why, remember that there is a small frictional torque opposing the turning of the wheel. In order to keep the wheel turning as the bike descends the hill, there must be a small backwards force on the bottom of the back tyre.

Hope this helps.
 
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  • #8
There is a Newton third law pair of forces involved with friction. The direction of friction depends if you mean the force the tire's contact patch exerts on the surface of the incline, or the force that the surface of the incline exerts on the tire's contact patch.
 
  • #9
Thank you guys
 
  • #10
hi paras02! :smile:

"In particular, the friction from the road on the driving or braking wheels of a car is in the same direction as the acceleration or braking, but the friction on the non-driving or non-braking wheels of a car is in the opposite direction."

see the pf library on direction of friction for more detail :wink:
 
  • #11
tiny-tim said:
"In particular, the friction from the road on the driving or braking wheels of a car is in the same direction as the acceleration or braking, but the friction on the non-driving or non-braking wheels of a car is in the opposite direction."
"Friction" or "rolling resistance" for the non-driving tires? There is some friction force at the axles of the non-driving wheels (but that is effectively a small amont of braking), which will also mean some friction force at the tires.
 
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What is rear wheel friction?

Rear wheel friction refers to the resistance or force that occurs between the rear wheel of a bicycle and the surface it is moving on. This friction is caused by the contact between the tire and the ground, and can affect the speed and efficiency of cycling.

How does rear wheel friction affect cycling on an incline?

Rear wheel friction plays a crucial role in cycling on an incline. As the incline increases, the force of gravity pulling the cyclist and the bike downhill also increases. This means that the rear wheel has to work harder to maintain traction and move the bike forward, resulting in increased friction and a decrease in speed.

What factors can affect rear wheel friction?

The main factors that can affect rear wheel friction include the type and condition of the tire, the surface being cycled on (e.g. pavement, gravel, dirt), the weight of the rider and the bike, and the angle of the incline. Additionally, weather conditions such as wet or icy surfaces can also impact rear wheel friction.

How can rear wheel friction be reduced?

To reduce rear wheel friction while cycling on an incline, it is important to ensure that the bike and its components are well-maintained, including regularly checking and inflating tires, and keeping the chain lubricated. Choosing a bike with wider tires and a lower gear ratio can also help to reduce friction. Proper cycling technique, such as distributing body weight evenly and pedaling smoothly, can also help to minimize rear wheel friction.

How can rear wheel friction be measured?

Rear wheel friction can be measured using a dynamometer, which is a device that measures the force needed to rotate a wheel. This can help to determine the amount of resistance and friction being experienced while cycling on an incline, and can be used to compare different tires and surfaces. Another way to measure rear wheel friction is by using a power meter, which can calculate the power output of the cyclist and provide information about the efficiency of cycling on an incline.

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