Best Motor for friction drive

Discussions related to motors other than hub motors.
This includes R/C motors, botttom bracket, roller and geared drives.
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evbkezzz   1 mW

1 mW
Posts: 15
Joined: Jul 02 2019 11:30pm

Best Motor for friction drive

Post by evbkezzz » Aug 13 2019 5:58am

What is the best motor for a friction drive for a 27.5in 2.25in tire?
I am planning to use a 6s3p battery pack.
I am currently looking at these two: ... motor.html ... motor.html

Should I go with a lower KV motor or high KV motor? I should stay below the legal speed limit of 25km/h.
Also, the motors are rated 10-12S Lipo, will they work with a 6s pack?

Drum   100 W

100 W
Posts: 255
Joined: Dec 29 2013 1:20pm
Location: Otaki New Zealand

Re: Best Motor for friction drive

Post by Drum » Aug 16 2019 2:37pm

For friction drive, the size of the tire doesn't matter.. the wheel is acting as an idler gear, transferring the surface speed of the motor to the road.
In other words, the road speed will be the same as the surface speed of the motor (or drive roller) regardless of wheel diameter.
You can work out the theoretical surface speed of the motor using battery voltage, motor kV and motor (or drive roller) radius. Actual speed under load will be a bit lower.

Motor selection will depend on the performance you are hoping to achieve.

Remember that there is a limit to how much power that can be transmitted from a roller to a tire by friction, especially if the tire is wet or muddy. If you haven't already, I suggest you read Kepler's threads.. he is one of the more experienced users of friction drive systems and has worked out clever solutions to the problems he has encountered in implementing them.

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