I have now the reply from the supplier:
So yoiur method of changing the wheel diameter is the only solution to set the speed limit below 25kph. Setting speed above 25kph works OK.Hi Tony,
I understood your explaination, the display and controller were made with 25km limit, can not set it below 25km and let it cut off at lower speed.
But set it above 25km is ok, but this not only depend on controller and display, also depend on the motor's speed limit, if the motor can not support, it will be no use.
Please check!
Best regards!
W.