# Gear Ratio for mountain board

So something that I can’t understand is the gear ratio. How do you decide what gear ratio you want. I’m not looking for a “you should use this gear ratio,” I’m looking for an explanation to understand it. I’m actually planning on building a gas powered board, but the gear ratio concept is the same - I just don’t understand how to get a good one to get the torque/speed ratio I’m looking for. Of course, it also depends on the size of wheels and the engines output power. I do understand that a 1:2 gear ratio means that one would have 10 and the other would have 20 teeth, but how do I know what the difference is between that and a 1:3 gear ratio? I guess I’m just asking how to calculate your speed/torque from the ratios?

A gas board has completely different torque output. I would recomend getting the biggest gear you can for the wheel and ordering 2-3 different motor ones from china. Once you find a good ratio, you stick with it

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I think it’s hard to give a guide as different people have different taste of what is torque or what not. You can calculate your speed here: https://calc./#/0

Things also depend on your motor kV and the motor size (i think with a gas there are differences as well), the wheel size and what not ever.

For a mountain board with 8“ and dual 170kV 6374 motors you would want something between 1:4 and 1:6.25 I’m gearing.

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Gear ratio can also depend on clutch settings. A high rpm clutch can get away with a taller gear compared to a low rpm clutch.

Why gas powered?

Sorry for the late replies. I’ve been out for a while. A) I believe it will be cheaper. I can get one engine for under 100\$ v.s. two motors, 90\$ per. Also, I should be able to go much further. Speed and torque should be increased (depending on which engine you get). Overall, it is just cheaper and better for me. And yes, I am aware of the disadvantages. I want to make a mountain board, and in general I think that a engine would be better for that.