Obviously the take off is the most important part of a gap, I found that getting to near to the edge of the object a massive benefit so its possible to use the pinch gap technique, where you use the deformation of the tyre around the edge of the object to your advantage to gain extra bounce as you take off. You want to be looking to preload your body just as much as your tyre, make sure that you squat down and then jump upwards not just out, gaining height at the start of a gap will add distance, and finaly when you are getting near your landing push your rear tyre out infront of you and use your legs to absorb the impact.
Have a look at this video I made about 2 years ago, there are some good clips of gaps that will show you the technique I use.
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I hope that helps
Adam