This was on the web site description.
So I am guessing you test with the ESC of your choice
TECHNICAL SPECIFICATION
Torque: 1N/m Max (with GT2 2mm Belt)
RPM: 100K Max
Units: English & Metric
Adjustable Reading and Logging Rate: 20Hz, 10Hz, 5Hz, and 2Hz.
PACKAGE CONTENTS
mini D for Motors Kit with 124mm Alu. Flywheel
540 Motor Mount
16T-3.175mm Shaft Pulley
mini D Electronic Board v1.1
**Motor, ESC & USB Cable are sold separately **
SUPPORTED OPERATING SYSTEMS
Microsoft Windows 7, 8, 10
I'm interested in knowing if you can vary the load at all, say I want to test a 17.5 at 22 amps to get an loaded rpm reading...or a 13.5 at say 37 amps at a lower voltage.