Getting a flatspot on your cheap skateboard wheels sucks! That is wheel you slide sideways on you wheel and rub a flatspot into the contact surface. It vibrates and makes a nasty buzzing noise wheel you roll on it. It all around sucks.
You can get them by doing powerslides or landing a trick wrong and sliding out sideways. The worst way is hitting a small rock or pebble. Screeching to a quick halt.
A wheel with a flatspot makes a zipping noise as it rolls over the flat area. It is loud and makes you board vibrate. If you are lucky the flat area will wear out within an hour of good skating. If it is bad or you have cheap skateboard wheels then its time for a new set.
I'll tell you, any serious skater has had themselves smashed to the ground like this.
What happens is a small pebble can get caught under your wheel while you are rolling. It can get wedged between the wheel and the ground. This stops the wheel dead and knocks you down. Smash! Leaving you writhing on the ground and a flatspot on you wheel.
There is often a stone with a skid mark trail next to it left on the ground. No joke, it leaves a skid mark.
The wedged pebble stops the rolling wheel and forward motion of the skateboard. Causing it to slide on the ground a bit and usually wearing a flat area into the roundness of the wheel.
Meanwhile the skater who is still moving forward gets thrown off the board pretty quickly. Often right to the ground in a painful quick smash.
So you are pissed because it hurt, people are laughing at you and now you wheels are messed.
On the wheel it looks like a flat clean spot across the surface of the wheel. I'll get a photo the next time I am lucky enough to have this happen to me. This wasn't so bad. I didn't fall and the flatspot eventually wore away.
You can wear a flatspot round again by rolling on a rough road or side walk. If it's bad you may need new wheels.
The best way to avoid getting flatspots is to avoid cheap skateboard wheels. Get good quality wheels, not blanks. Blanks are often made of cheaper material and will often flatspot. Some wheel companies are now coming out with formulas that say "no flatspots". I find the Bones wheels are usually pretty good for this.
A good quality formula found in label brand skateboard wheels will do you better than cheap skateboard wheels.
You can avoid getting smashed super hard from a stone, sometimes. It will happen to everyone no matter what.
To keep from getting thrown off you board too bad you need to stay light on your feet. As you get better at skateboarding you will get better at avoiding the flatspot crash. That is if you survive the first few that happen to you.
Need tips on how to fall without injury? Go here.
I cannot say this enough. The best way to avoid flatspots is to stay away from blank and cheap skateboard wheels. Get good quality wheels and you can ride them for a long time.