Gear ratio?

I have a target gear ratio (15:1) but I don’t know what the original gear ratio was. (this one is obv simplified) What gears would produce that ratio? (I’ll take any answers, math too, anything that can help me figure this out myself for the next time) Thanks!

You can try playing around with this tool to find out what gears to use : Gear Ratio Calculator | Evolvent Design

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I believe that it would use a compound gear ratio going from 60:12, and on the same shaft of the 12 tooth gear, use a 36 tooth gear that goes to another 12 tooth gear. If you have any more questions, feel free to reply.


15:1 is a very odd gear ratio. I would recommend a 5:1 or 6:1 for a flywheel. If you do want to use 15:1 tho, the math is really simple. Take a 5:1 gear ratio (12:60) and compound it with a 3:1 ratio (12:36). This will give you 15:1 because 3 x 5 = 15.


Microsoft excel has a solver feature that can figure out ALL gear combinations that will yield your desired ratio. It’s also a good opportunity to learn about a very powerful piece of s/w (excel).

Note: this requires the desktop version, not online. Online just has basic functions.