Did you never do bunny-hops on a BMX as a kid? Same thing. You don't need front suspension. As you approach the curb kinda squat down on your bike, then straighten your legs, pull up on the handle bars and push down on both pedals so that you're transferring your weight into the rear wheel and just as all of your weight pushes down through your legs/pedals/wheel then you kinda jump - your feet don't leave the pedals though...when you jump your bike comes up with you and stays in contact with your feet. Pretend your rear wheel is your feet, and you're pushing off the ground with your rear wheel. You can practice on the street in case you're worried you won't clear the curb. Jump manhole covers or sticks.