X1 Pro Gen 4: Motor Resistance When Pushing Backward

Symptoms

You are experiencing high resistance when pushing your bike backward or struggle to push your bike backward at all. There may or may not be a mechanical noise and you may or may not be able to turn your bike on.

Reasons

A controller mosfet has failed
There is a mechanical failure
Something's wrong with your bike's drivetrain

Checklist

Remove your bike chain
Turn the chainring (not the crank) backward to see if you still have a resistance
*If there is no resistance and no noise when turning the chainring, then inspect your bike's drivetrain instead
Skip to Solution No.4 if your bike's drivetrain is an issue.

Troubleshoot

Put your bike's chain back on.
Turn on your kit at the display.
*If you cannot turn on your kit at the display and there is an inconsistent resistance (i.e there may be more resistance when you try to roll your wheel back faster) when trying to roll your bike backward with no mechanical noise, then a mosfet inside the controller has failed. Continue to the Solution section below.
If you can turn on your kit, switch to the highest assist level, lift your rear wheel, and push down on the throttle. Check if you have mechanical noise and high resistance (power reading but no movement) or if you have little to no movement (like something is stuck) without mechanical noise. Either one is a mechanical issue.
Look through the glass cover on the motor and check if you see any dust particles or debris. If yes, then there is an issue with your rotor. Skip to Solution No. 2 below.
Remove the kit from your bike and split the gearbox from the motor. Kindly see the below video on how to disassemble the kit.
**** tear down video coming soon
Once disassembled, check for any debris particles or metal shards in between the gears and grease. If there are any debris particles, metal shards, or visible signs that the gears are damaged, you will need to replace the gearbox. Skip to Solution No. 3.Ha
If there are no signs that the gears are damaged, turn the gearbox output shaft clockwise and anti-clockwise by hand. If it can turn freely in both directions, then the gearbox is still in good condition. If not, open up the gearbox cover and inspect the sprag clutch. Also, check for any signs of scratch marks on the inside of the gearbox cover. Check if the key on the sprag clutch is protruding outwards. If the key is protruding outwards, you will need to replace the gearbox. Skip to Solution No. 3.
If the gearbox is still in good condition, redirect your attention to the motor and turn the sun gear by hand. If you cannot freely turn the sun gear, then the motor has failed. Go to Solution No. 2.

Solution

1. A controller mosfet has failed

Replace the X12 controller directly if you cannot turn on your kit and have inconsistent resistance when rolling your bike backward without mechanical noise.

2. The motor or rotor has failed

Replace the motor directly.

Please note that CYC or authorised service centres and/ or resellers will not supply the rotor or stator separately.

3. The gearbox has failed

Replace the gearbox directly.

Please note that CYC or authorized service centers and/ or resellers will not supply the brass gears separately. In the case where the sprag clutch alone has failed (not as a result of the above-mentioned scenarios), the sprag clutch alone may be replaced. In the above-mentioned scenarios, the whole gearbox will need to be replaced as the carrier has also been damaged.

4. Something's not right with your bike's drivetrain