Its all about the position and angle of the leg.
Bent Right Leg, behind your body - Toe pointing to the right = moving over to the right side of the lane
Bent Left Leg, behind your body - Toe pointing to the left = moving over to the left side of the lane
Leg Straight Down - Toe skywards = Obstacle on the road
Standing up on the pegs - swinging your leg from front to back = Dog on the road get ready to kick it
Knee out - Tap side of the leg = Pull up along side the rider
Hand out to the side - up/down movement = Slow down nasty corner coming up
Index finger pointing skywards, hand swirling motion, - 5 fingers spread out - Close fist pull down = ** cue Arnie voice ** Get to the chopper 5 minutes GO!!
Note: i just make this shit up dont listen to me. 
