Gotrax R2 Manuel D'utilisation page 12

Install the front wheel
Remove the plastic protective sheet inside the brake.
Loosen the front axle screws (it doesn't need to be totally loose, just to a suitable
position for installation).
10
Slowly install the front wheel on the front fork and
the brake pads in the brake. Note: The spacer is as
shown in the picture, the spacer hook needs to be
hung into the front fork, and the positions of the
spacers on both sides are the same.
screws of the front wheels on both sides.