Wheel size vs speedometer.

[Keith LaFetra]

Hi guys . I was asking a fee days ago about my motor acting strange after heating up at low speeds. Someone mentioned wheel size which I found was the easiest thing to change so at 26" the motor runs way smoother but the speedometer is way off. The speedometer is almost perfect set on wheel size 16 but runs horribly rough! I'm new to this stuff. Any directions would be appreciated.

 

[calab]

Changing tire size from 29 to 26 requires a new lace job with a new rim and new spokes/nipples.

What speedometer are you talking about. You have to go intot he settings of your Cyclocomputer and change the mm number for the diameter of the wheel. You use a tape measure and wrap it around the tires tread and measure. If ts a KT display unit, or a CA then again you have to go into settings.

In general
Small wheel in hub is more torque and less speed
Large wheel in hub means less torque more speed
Change wheel size, changes the speedometer calibration. Same with change tire sizes on vehicles, the speedomenter requires recalibration.

 

[Keith LaFetra]

I guess my explanation was vague. I have a nb power display with 150a sabvaton controller and 5000 watt hub motor on 20 inch wheels. The bike runs smooth when I set the wheel size to 26 on the display, but speed is accurate when set to 16 inch wheels on display however it runs very rough at lower speeds. This is all due to settings on the display not physically changing the wheel size

 

[lnanek]

Lying to the controller and saying you have a larger wheel size than you do can cause things like speed limiters to engage earlier than otherwise. Since the controller thinks your bike is rolling much farther per rpm. Speedo would be inaccurate as well since speed is calculated based on either rpm of the motor or the wheel and the size of the wheel.

 

[Keith LaFetra]

Lying to the controller and saying you have a larger wheel size than you do can cause things like speed limiters to engage earlier than otherwise. Since the controller thinks your bike is rolling much farther per rpm. Speedo would be inaccurate as well since speed is calculated based on either rpm of the motor or the wheel and the size of the wheel.

I understand that but telling it the truth runs way more rough. It runs great when lying to it. Do you think maybe it's a phase wire issue? Should I play with some different combinations doing hall tests in between?

 

[TommyCat]

Have you set the correct number of motor pole pairs under the motor tab?
Correctly saving the parameters? I.E. They are the same after reboot.