1) If the noise is coming from the wheel and occurring mostly during hard braking, it may be a belt skip. See our article on how to diagnose and fix a belt skip.
2) Alternatively, it could be that the flanged bearing in your drive wheel is not set properly. See how to access it here.
It is very important that this bearing is sitting flat. Press it in until it is flat and flush. If it is not sitting flat, then your drive gear may not sit properly, as seen below:
3) If the noise remains, then remove the rear wheel spacers, seen here:
4) If the board makes a clicking sound as it rolls, check for debris lodged in the wheel, belt, or drive gear.
5) If the noise does not sound like the one in #1 linked above, and adjusting the flanged bearing in #2 and removing the two spacers in #3 don't fix it, please send us an email to firstname.lastname@example.org with the subject "Board making odd sound, video attached."
In your email please include a video of the noise you are hearing and we'll get back to you with how to fix it.
My board is making a weird sound