Remove the washer and the nut as shown in the photos below from both sides of the front wheel hub.
Please note the disk rotor should go in the tiny space between the brake pads.
IMPORTANT: Please note this step is very sensitive and if done wrong, the brake pads or the disk rotor can be damaged.
Ask someone to hold the front tyre (photo 4) and then lift the bike and carefully lower the forks until the disk brake rotor is inserted between the brake pads and the axel fits nicely in the front forks.
Insert the locking washer to the axel on the right and
ensure it is locked just as shown in photo below.
Please note the washer tap should be inserted in the hole on the fork so that it locks. Then hand tighten the nut. Do the same steps on the left.
Now tighten the nuts on both sides as shown in photos below. Please note in this step, you should tighten the nut on one side a bit and then tighten the other nut a bit and repeat the process until both nuts are fully tightened. While tightening the nuts, you should try to keep the tyre centred between the forks. If after the nuts are tightened, the tyre is leaning to one side more, please loosen both nuts and try again.
IMPORTANT: In this step the bike should not be on the kickstand as centring the tyre between the forks while the bike is on kickstand is difficult.
IMPORTANT: In this step the bike should be on the wheels (not upside down on the handlebars). The weight of the bike helps the tyre’s axel be fully inserted into the fork dropouts and makes the tyre be centred between the forks easier.