To control the motor power of my solar bike as easy as possible, I have developed an ergonomic e-bike thumb throttle switch. It needs just a small thumb movement.

Normally, such a throttle is mounted between grip and the brake lever which increases the distance between them, see for instance the Bionx throttle or the Shimano switch unit SW EM800 L. That's not handy. That's why I made a throttle that is mounted on top of the brake lever clamp so that no extra space is needed on the handlebar.

Thumb throttle advantages

A thumb throttle switch is more convenient than a turning throttle because you don’t have to constantly hold the throttle position. It is pleasant to use, it needs just a small thumb movement and the up and down buttons are very sensitive.

Note that, with pedal-assist e-bikes, you have still to turn the pedals (by law), but once a minute is fine. A PAS sensor is needed here to detect if the pedal is turning.

Electrical connection to the motor controller

My thumb throttle only contains two switches and doesn’t have an analog output as the commonly used Hall sensor throttles:

I use the thumb throttle on my Maxun One solarbike and it is connected to a self-developed two-wire bus. The thumb throttle cannot be connected to a standard motor controller because these have an analog input.

Design files

You can download the files from GitHub here.

Sensitive tactile switches

Since you have to press the buttons very often, very sensitive tactile switches are used so that you only have to press very lightly: the Panasonic EVQ-P6DB35 tactile switches are also watertight (IP68)

 These are the parts:

 This is the throttle with the PCBs glued on it:

 Glue it to the brake lever with 3M VHB tape:

 Side view:

 The throttle internal wiring:

Links

Guide to Hall Sensor Throttle operation, testing, and modification.