Installing a hub motor kit is the hard part of the job: wheel off, disc rotor and freewheel on, axle bolted into the dropouts, cables routed. Finding out afterwards that one part is dead, missing or plugged in wrongly means undoing much of that. A short bench test, with everything laid out on the floor or a bench, catches those problems first.
What the test proves, and what it does not
It shows that the parts in the box power up and work together: motor, controller, display, throttle, brake sensors, pedal sensor and light. It does not show that the wheel fits your frame. Dropout width, axle diameter, freewheel or cassette, and frame clearance are mechanical questions the bench test cannot answer; the last section points to our guides on dropout width and axle fit.
It also does not prove that parts from different kits or brands will cooperate. A display that lights up is not proof the controller and display speak the same protocol; the KT vs No.2 protocol guide explains why.
Where this comes from
The sequence below follows one published install video for a 500 W rear-hub kit. Its manual includes a section called the pre-installation test, and the builder worked through it before touching the bike. Connector colors and layouts differ between kits, so use the manual that came with yours and treat our steps as the general pattern.
Set up
- Lay every part out on the floor or a bench.
- Check that the battery's nominal voltage matches the controller's rated voltage (look on the controller's label). Battery, controller and motor have to agree.
- Put the wheel where it can spin freely. Keep fingers, loose clothing and cables clear of it.
- Keep the battery switched off while you connect everything. Connect it last.
Connect in this order
- Motor extension cable to the controller, lining up the arrows.
- Pedal-assist sensor to the controller. In the video this plug fitted only one way.
- Headlight, if the kit includes one.
- The multi-lead cable to the controller, again matching the arrow. Then the two brake levers, the thumb throttle and the display. In the video the brake plugs fitted only one way too.
- The battery connector, with the battery still off and the exposed ends not touching anything.
If a plug will not seat, stop and look for the arrow or key instead of forcing it.
Power up and check each function
Before switching on, look over every connection once more. Then turn the battery on and hold the display's power button.
- Throttle. In the video the throttle did nothing at assist level 0 and worked at level 1. We have not confirmed that every display behaves this way, so if your throttle seems dead, try level 1 with the wheel clear before blaming the throttle. Our throttle testing guide covers the multimeter checks.
- Pedal sensor. Turn the pedal sensor by hand. In the video, the wheel spun in response.
- Light. On the display in the video, holding the plus button switched the headlight on and off. Your buttons may differ.
- Brakes. Squeeze each lever in turn and watch the display for a brake indicator; in the video it was a red icon. If nothing shows, see the brake sensor guide.
If something does not work
Switch the battery off first. Then reseat each connector fully. Several of Bafang's DP C-series display manuals say to restart the system when an error code appears and, for the throttle-fault code, to check the throttle connector and then disconnect the throttle to see whether the fault remains. Codes differ between displays, so read your own display's manual.
Change one thing at a time so you know what fixed it. If you have a matching bike or a spare part, the two-bike cross-swap test can show which part is at fault; read its rules first.
If you have mixed a motor and controller from different sources, shuddering or stuttering can point to phase and Hall wires that do not match. Read the phase and Hall wire color guide before trying again. If the motor runs hot or draws unusually high current with no load, cut power at once; carrying on can damage the motor and the controller.
What the bench test cannot catch
Do the mechanical measuring before you order, or at least before you mount anything. Measure your dropout width and axle size against the hub motor sizing guide, and check whether your frame uses a thru-axle, which a bolt-on hub motor will not fit (why).
Once the test passes, install the kit. We suggest repeating the power-up check when everything is on the bike, since a pinched cable or loose plug can still show up there.