Why Is the Mass of a Wheel Concentrated on the Rim?

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Discussion Overview

The discussion centers around the concentration of mass in the rim of a wheel, particularly in the context of vehicle wheels such as those on cars and bikes. Participants explore the implications of this design choice, including its effects on moment of inertia and practical applications.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant notes that the mass is concentrated on the rim to increase the moment of inertia, questioning the practical use of this design.
  • Another participant asks for clarification on the type of wheel being discussed, indicating that the context may influence the answer.
  • A participant specifies that they are referring to vehicle wheels, emphasizing the importance of the outer rim for supporting the tire.
  • One participant challenges the idea that increasing moment of inertia is beneficial, stating that it requires greater power for acceleration and can lead to negative consequences such as increased unsprung mass.
  • A reference to unsprung mass is provided, suggesting that minimizing wheel weight and moment of inertia is generally preferred.

Areas of Agreement / Disagreement

Participants express differing views on the implications of mass concentration in the rim, with some supporting the idea of increased moment of inertia as beneficial, while others argue against it, highlighting potential drawbacks. The discussion remains unresolved regarding the overall benefits versus drawbacks of this design choice.

Contextual Notes

Participants have not reached a consensus on the advantages or disadvantages of concentrating mass in the rim, and there are varying assumptions about the implications of moment of inertia and unsprung mass.

saravananrame
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A small confusion ! Why is most of the mass of the wheel concentrated on the rim ? I know that it is to increase the moment of inertia , but what is the practical use of doing so ?
Thanks in advance !
 
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saravananrame said:
A small confusion ! Why is most of the mass of the wheel concentrated on the rim ? I know that it is to increase the moment of inertia , but what is the practical use of doing so ?
Thanks in advance !

I'm afraid you'll have to be a little more specific here. What type of wheel are we talking about?
 
A normal vehicle ( car , bike ) wheel where mass is mostly concentrated on the outer edge ( outer rim ) . I guess the word rim suits here . I mean the outer curved circular thingy !
 
saravananrame said:
A small confusion ! Why is most of the mass of the wheel concentrated on the rim

To support the tire. Try mounting a bicycle tire on spokes..impossible.

I know that it is to increase the moment of inertia

No. that is an unwanted consequence. A high MoI means greater power is required for acceleration.

overall wheel weight has other negative consequences as it increases un-sprung mass.

http://en.wikipedia.org/wiki/Unsprung_mass

So generally you want to minimize the wheels weight and MoI.
 

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