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## Main Question or Discussion Point

I have a scooter with a 5 inch diameter wheel and I want to make it go 25mph with a motor that has this specs.

====

Power 0.35 hp @12v 1.43 hp @24v

Torque 0.47 lbf*ft @12v 0.97 lbf*ft @24v

Efficiency 70% @12v 76% @24v

Speed 1260 RPM / Volt

Voltage 12 volts or 24 volts*

Weight 11 oz.

Output Shaft 5mm dia x .75" long

Diameter 1.7"

Length 2.8" (from face)

Face Mount 2 M4 holes 1.14" apart

===

I use this equation to figure out the RPM of the wheel for 25mph.

RPM*(((D*3.14)/12)*60)/5280)=MPH

Calcuated RPM for 25mph is = 1680 RPM

i'm planning to use 17 volts, thus the motor rpm would be 1260*17=21420 RPM

Now i'm finding the gear reduction. 21420/1680= 12.75

5"/12.75 thus .39" is the required gear size that is attached to the motor.

Is the .39" gear size the diameter, radius or circumference???

i'm not using a sprocket because it is friction drive.

Are there any potential problems with this setup? Is my calculation correct?

====

Power 0.35 hp @12v 1.43 hp @24v

Torque 0.47 lbf*ft @12v 0.97 lbf*ft @24v

Efficiency 70% @12v 76% @24v

Speed 1260 RPM / Volt

Voltage 12 volts or 24 volts*

Weight 11 oz.

Output Shaft 5mm dia x .75" long

Diameter 1.7"

Length 2.8" (from face)

Face Mount 2 M4 holes 1.14" apart

===

I use this equation to figure out the RPM of the wheel for 25mph.

RPM*(((D*3.14)/12)*60)/5280)=MPH

Calcuated RPM for 25mph is = 1680 RPM

i'm planning to use 17 volts, thus the motor rpm would be 1260*17=21420 RPM

Now i'm finding the gear reduction. 21420/1680= 12.75

5"/12.75 thus .39" is the required gear size that is attached to the motor.

Is the .39" gear size the diameter, radius or circumference???

i'm not using a sprocket because it is friction drive.

Are there any potential problems with this setup? Is my calculation correct?

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