A barley grind is a front side 180 switch smith grind… To be able to do this trick, you have to learn front side 180 ollie and switch smith grinds… So here's the trick: You're riding parallel to a ledge or curb with a good amount of speed (fast), and try to be as close to the curb as possible, but not too close. Then do a front side ollie, but be careful not to pop too big, because then youth front truck will fly over the curb. So pop a solid one, and if your done it right, your front truck should be locked in the switch smith grind position. But if your weight is not centered over your front truck you won't be able to grind. And lean a little bit back. You can help with your other leg by pushing the board to the side of the curb or ledge, this will help to keep your board in the grind position…
Good Luck!