biketrials riding techniquesFor long gaps
If you can afford the space for half a full crank turn. Also a good starter for the double bounce pedal hop climbing technique where you need to launch a fast pedal hop to build momentum.

Neat synchronisation of pedalling and jump impulsion
1° Start pulling on the bars, slightly lifting the front wheel with your bad-foot pedal (left if you are right foot). 2° Accelerate the move on your right foot pedal, with full extension while kicking on your good pedal. 3° The kick and jump extension must be synchro with the rear wheel leaving the edge of the gap. Full extension over the gap.
When the rear wheel touches down, full brakes on (else, you'll fall on your back). Start from smallish kerbs to get the feel.
See the move in a video

How get the right synchro:
The first quarter turn with the good pedal is just to control the speed of approach of the gap, the second quarter turn on the goofy pedal is to lift the front wheel, keeping it horizontal in the air while folding back like a spring before extension. This brings you ready for an accelerated kick in your right pedal with extension for the jump. Before the pedal kick, try to keep the front wheel as low as possible on the horizontal, to have extra torque when giving the pedal kick (its like lowering the front wheel before a normal pedal hop).
video
slow-motion over salted water
video
Pedal hop over a gap and up a step
by César Cañas at a trials demo
Shrinking the run up distance
You must learn your distance marks, which depends on the gear ratio you use. Do this by moving the bike backward, from the final pedal position before the kick, to the initial pedal start position (just let the pedals' position tell you when you are there).
After a while, you can play around by reducing the run up distance to a minimum, starting directly on your bad pedal (then body movement plays a bigger part). video
José closing a huge gap