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I'm trying to find a decent cheap truing stand online for truing my bicycle wheels.Where would be a good place that you would recommend and at a good price?I'll choose the best answer!
Answer
If you are only looking to true your wheels once, I'd recommend taking it to your local bike shop as they have the skills and tools needed to do it properly. If you want to invest in a truing stand for doing this on a regular basis, I'd keep your eye on Performance Bike's website. They regularly have sales of up to 20% off and if you catch it at the right time of the month you might hit a Free Shipping sale as well. They have good quality stands at a decent price. The one down in my source is a very high quality model by Spin Doctor, and while the price may seem a bit high it's not bad when you take off the 20% (30% if you're a Performance member). Spin Doctor tools last forever and have great resale value.
If you are only looking to true your wheels once, I'd recommend taking it to your local bike shop as they have the skills and tools needed to do it properly. If you want to invest in a truing stand for doing this on a regular basis, I'd keep your eye on Performance Bike's website. They regularly have sales of up to 20% off and if you catch it at the right time of the month you might hit a Free Shipping sale as well. They have good quality stands at a decent price. The one down in my source is a very high quality model by Spin Doctor, and while the price may seem a bit high it's not bad when you take off the 20% (30% if you're a Performance member). Spin Doctor tools last forever and have great resale value.
Is the simplest way you can define it, what is radius of gyration and how do you find it?
Q. What is it?
What is it used for?
What does it explain?
And how do you find it mathematically?
What is it used for?
What does it explain?
And how do you find it mathematically?
Answer
The moment of inertia of a body is â m(i) . r(i)^2
Which means that you take all the individual masses that make up the body , multiply each one by the square of the distance it is from the axis of rotation and add them all together.
For each body there can be any number of axes of rotation and so there can be any number of different Moments of Inertia for the same body.
We concentrate on simple shapes with axes of rotation in obvious places.
For example - a bike wheel with all the mass in the rim ( zero weight spokes ! ) , and every bit of that mass the same distance R from the centre of the circle . So the MI of the wheel is M . R^2
Next step = A solid disk ( like a CD ) , spinning round its centre. This time some of the mass is closer to the
centre, and contributes less to the MI .
The total MI for a solid disc can be worked out ( it needs calculus ) and it comes to 1/2 M R^2
Another way to write this would be Mr^2 where r is the radius of gyration - the single value for the average distance from the rotation axis that will give you the correct moment of inertia
In this case r = R/â2
All moments of inertia can be represented by the formula MI = M . r^2 where the r ( the radius of gyration ) is the representative distance that gives you the correct answer.
That is all it is.
A solid ball spinning about a central axis, has a moment of inertia of 2/5 . M . R^2
so its radius of gyration will be 0.4 . M . R^2 = M . r^2
r = R . â 0.4 = 0.6325 R
You don't usually work out the radius of gyration.... you measure it practically by seeing what torque is needed to spin an object, work out the moment of inertia ( by experiment ) and then calculate what the gyration radius must be.
Unless you are doing engineering, I would just ignore it.
The moment of inertia of a body is â m(i) . r(i)^2
Which means that you take all the individual masses that make up the body , multiply each one by the square of the distance it is from the axis of rotation and add them all together.
For each body there can be any number of axes of rotation and so there can be any number of different Moments of Inertia for the same body.
We concentrate on simple shapes with axes of rotation in obvious places.
For example - a bike wheel with all the mass in the rim ( zero weight spokes ! ) , and every bit of that mass the same distance R from the centre of the circle . So the MI of the wheel is M . R^2
Next step = A solid disk ( like a CD ) , spinning round its centre. This time some of the mass is closer to the
centre, and contributes less to the MI .
The total MI for a solid disc can be worked out ( it needs calculus ) and it comes to 1/2 M R^2
Another way to write this would be Mr^2 where r is the radius of gyration - the single value for the average distance from the rotation axis that will give you the correct moment of inertia
In this case r = R/â2
All moments of inertia can be represented by the formula MI = M . r^2 where the r ( the radius of gyration ) is the representative distance that gives you the correct answer.
That is all it is.
A solid ball spinning about a central axis, has a moment of inertia of 2/5 . M . R^2
so its radius of gyration will be 0.4 . M . R^2 = M . r^2
r = R . â 0.4 = 0.6325 R
You don't usually work out the radius of gyration.... you measure it practically by seeing what torque is needed to spin an object, work out the moment of inertia ( by experiment ) and then calculate what the gyration radius must be.
Unless you are doing engineering, I would just ignore it.
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