Bicycle racers have begun using solid disks for wheels rather than spokes and rims. What is their reasoning f?
Tuesday, December 7th, 2010 at
10:13 am
Bicycle racers have begun using solid disks for wheels rather than spokes and rims. What is their reasoning for doing so?
A. A solid disk has a moment of inertia of ½ MR2 and a thin hoop has a moment of inertia of MR2, therefore the disk should be easier to start moving.
B. The solid disk has less mass.
C. The solid disk has less air resistance.
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Why did you answer your own question?
The closest you can get to a reason is A…but it by no means is the reason. In fact, more of the opposite of the reason.
The real reason is that they WANT greater rotational inertia. Rotational inertia gives them a greater rotational inertia to mass of the ENTIRE human + bike frame + wheel system.
This ultimately means they can get a better inertia to friction ratio, and have friction slow them down more.
If you try to make a hoop or a filled disc…you will have a very difficult time making them both of the same mass…or even of identical rotational inertia. Most likely, if you use exaclty the same material, you WILL have greater mass and greater rotational inertia for the filled disc.
That is why they use discs…so they can get more of the mass that they have in the rotational mode of motion, and get more inertia without getting more friction.
If you try riding a bicycle, and if you understand inertia in full…and if you try riding a bicycle race…you will realize that inertia is your friend…not your enemy.
don’t know but i’d love for you to sit on my bicycle seat. [Sniff, Sniff]