Bunny Hop Very High With Bicycle:

Use the following trick to jump as high as a telephone pole on a bicycle (bunny hop). A few or more tries may be required to learn the correct timing of the buttons. First, make sure you have a machine gun. Hold L to set up for a bunny hop. Then, release L and immediately press B to fire your machine gun. If done correctly, the bike hops many times higher into the air than normal. It is possible to jump over a two story building from flat ground by doing this. Additionally, hold L to bunny hop, and the exact moment after you release L, press or tap B. This only works when you have a drive by capable weapon equipped. You will be able to jump slightly higher than power lines. Sometimes it can be very difficult to do, as you timing must be precise.