START ENGINES
With your right or left arm extended, move your finger in a circular motion.

LEFT TURN
Raise your left arm horizontal with your elbow fully extended.

RIGHT TURN
Raise your left arm horizontal with your elbow bent 90 degrees vertically.

HAZARD LEFT
Extend your left arm at a 45 degree angle and point towards the hazard.

HAZARD RIGHT
Extend your right arm at a 45 degree angle and point towards the hazard.

SPEED UP
Raise your left arm up and down with your index finger extended upward. This indicates the leader wants to speed up.

SLOW DOWN
Extend your left arm at a 45 degree angle and move your hand up and down.

SINGLE FILE
Position your left hand over your helmet with your fingers extended upward.

TIGHTEN UP
Raise your left arm and repeatedly move up and down in a pulling motion. 

STOP
Extend your left arm at a 45 degree angle with the palm of your hand facing rearward.

TICKED OFF  

Not For The Police 
Extend your left arm straight out with your elbow bent 90 degrees. Carefully extend your middle finger to clearly demonstrate your dissatisfaction with the other guy. NOTE: It is not recommended you do this when you are alone.

STAGGERED
Extend your left arm upward at a 45 degree angle with your index and pinkie finger extended. 

Hand Signals

The Ann Arbor, Michigan HOG Chapter kindly provided the below graphics. They are used with their permission.