Lower than expected top speed

[Bradda]

Hi everyone. I'm new to this sphere but have extensive experience in the push bike world and decent experience with RC hobbies.

I built a conversion kit for my 700c commuter bike.

My question is regarding top speed. It pulls well up to ~16km/h then feels like it cuts power. I expected faster.

The motor/controller/display came as a kit in Australia, seller stated it's for a 16" wheel that should be limited to 25km/h and that because I built a 700c wheel it won't go 25 (my maths says hub RPM x rollout = speed, and 700c>16")

The hub is a Bafang G311 250, external casing says D15, internal spline says D09, windings are 16 pole 18 slot, though I don't know what that means or if it's helpful.

The supplied display has no part number or markings. The controller looks like a generic 6A continuous unit.

The battery is a 36v 10s2p made from Samsung 21700-50S cells with a DALY 20A BMS.
700c wheel with 37mm tyre.


Have I just mismatched components and 16km/h is all I should expect from it or is the controller or display limiting my speed?

 

[Bradda]

https://www.aliexpress.com/item/1005008341638656.html

17A with S900, manual online says display can modify pole pairs, max speed, displays watts, has Z91 plug and fits my 31.8 bars.

 

[99t4]

if it has the right motor pin out, is there a potential it won't like the hall sensor/speed sensor output?

Just be aware there is no real standard phase wire/ hall sensor wire (pinout or wire color) among products, even within a single mfr's/vendor's offerings.

 

[Bradda]

Just be aware there is no real standard phase wire/ hall sensor wire (pinout or wire color) among products, even within a single mfr's/vendor's offerings.

Thank you, that is helpful to know.

 

[Bradda]

An update for anyone interested.
I got the below (above too) kit from AliExpress, all installed fine, I did need to swap the wiring for the pedal assist sensor.

So far it's great, though the amp limit in the display doesn't seem to work as the wattage readout peaks above what I'd like, it does make me wonder if a lower rated controller would have been better, but that's for another day.

For now the speed limit functions exactly as I want, and using 9 speeds I have nearly 1km/h increments from 25 down to 14.

I've done a few rides now and I average around 23km/h and on a round trip to work which totals 35km I used ~30% of the battery!