Assuming all other factors being equal, which of these rotors would have the least amount of drag brake effect:

12.0 x 7.25 x 25.3

12.0 x 5.0 x 23.0

If the Gauss value is the same ... the will have the same drag brake effect.

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Muchmore Racing. Co., Ltd.

But what does it say, they are only dimensions, it says nothing about the actual strength of the magnet

Those rotors will have different amounts of magnetic material in them. If the gauss is the same per unit density of the material, then the 12.0 x 7.25 x 25.3 will have less gauss overall and should have less drag brake effect. Use area of a cylinder - area of the smaller cylinder to solve.

OP didn't say which factors are the same. If you put both on a rotor checker / Gauss meter and they read the same ... they should have the same drag effect.

Go back and read my post, I did put a qualifier in there...

There is no gauss rating listed, they are only listed as having N35 composition.

If you do the math, there is quite a bit less material in the first rotor, about 25% less. I would still guess the first rotor would have less drag brake.

EDIT: If you have a large open space you can probably get an idea from getting to full throttle and letting off and use a stop watch or measure the stopping distance.

I’m not sure you understand how magnets are made. They start out completely unmagnetized, from a powder that is sintered in a die. Then they are put into a very powerful electromagnet that magnetizes them. The power of the magnetizer does not give them their ultimate strength, the composition of the magnet is what gives them their strength.

And there are not dozens of different compositions either, there are only a handful.

So if I’m comparing two rotors made from the same compound but have differing lengths and mass, they will have different strengths. But maybe that really only applies to their saturation point when the core winding is fully electrified. So maybe since the diameter of them is the same, it’s possible they could have the same force against an idle core which means the length of them will determine the drag brake effect.

But I don’t know. So I asked here thinking maybe someone else has already experimented with this.

I read it the first time... OP gave us an impossible question. "all other factors being equal" ... Overall Gauss being equal cannot exist while Gauss density is equal. Yet they are both factors.

Two rotors from the same manufacturer... made with the same process... out of the material ... to the same dimensions... with the same part number ... can and will have different overall Gauss readings. But since you know so much more about how magnets are made I guess you should be able to answer the question on your own.

It's funny really. Cause you just posted what I took the OP to mean by all other things being equal, ie, apple = apple, same company, dimensions, etc, same gauss. We both know they can be different by quite a bit, but that is the assumption to all other things being equal. Where you ran with all other things being equal was orange = apple, by saying rotors of completely different sizes would have the same gauss reading.

OP should have posted what was equal as all things can't be equal. Particularly given that Mike historically "seems" to know more than anyone trying to answer his questions.

The irony.

I guess this time you at least waited for responses before insulting people. Must be growing up.