Howdy,

Most (small) DC motors will rotate at ~70 - 100 rpms (revolutions per minute) per volt of input.

so, I'll use 85 (kinda in the middle) for this example

a 12V motor will rotate at ~1,020 RPM's (12V x 85 = 1,020 RPM's)

If you supply it

...24V it should rotate at ~ 2,040 RPM's

...36V = 3,060 RPM's

...& @ 48V = 4,080 RPM's

Once you have an idea of the motors RPM"s, there are (3) main variables to figuring out how fast a (given) motor will propel your car/kart

1.) Motor RPM's

2.) Gear Ratio

3.) Tire Circumference

By inputting your

...motor RPM's

...gear ratio

...& your tire circumference

in to this equation, you can figure out what your, potential, MPH would/could be

MS/GR=ASxTC=IM/FT=FMxHR=FHxMM= MPH

Motor Speed/Gear Ratio=Axle Speed x Tire Circumference = Inches per Minute traveled/Foot(12) = Feet per Minute traveled x Hour(60) = Feet per Hour traveled x MPH Multiplier(.000189) = Miles Per Hour

* Using e-Lemon-aid, as an example

[email protected] 24V (@ 2,000 RPM's) (Rated at 2,500 RPM's max)

...an 8:1 gear ratio

...& tires with ~38" circumference

2,000/8 = 250

250x38" = 9,500"

9,500"/12 = 791.67'

791.67x60 = 47,500

47,500x.000189 = 8.98 MPH

Motor speed is (2,000 rpm's) divided by the gear ratio (8) = axle speed (250)

Axle speed (250) times the wheel circumference (38") = inches per minute traveled (9,500")

Inches per minute traveled (9,500") divided by inches in a foot (12") = Feet per minute traveled (791.67)

Feet per minute traveled (791.67) times minutes in an hour (60) = feet per hour traveled (47,500)

Feet per hour traveled times miles per hour multiplier (.000189) = 8.98 MPH

Yup, according to the GPS she topped out at ~9 MPH

https://www.youtube.com/watch?v=uBT9B0sqNe4
Using it helps me to determine the potential speed of a vehicle (motor gear ratio & wheel size)

...it does NOT take into account wind resistance, rolling resistance, total weight & many other factors

...but, It'll at least gives me a rough idea or put's me "in the ball park".