The flank strap is a length of padded rope. Its purpose is to encourage the bull to kick. Without the annoying flank strap, the bull would run around the arena, not remain in one area trying to rid himself of the cowboy and flank strap.
How It's Used
The flank strap is slipped onto the bull when it enters the alley to the bucking chute. The slack is taken out of it just prior to the ride, but it's not pulled so tight as to injure the animal and is removed immediately after the ride.
Bull riding novices sometimes think the flank strap is tied around the bull's genitals. This would adversely affect the animal's performance and result in injury. Many champion bucking bulls are worth more than $50,000. Stock contractors don't risk injury to their investments.
When a bull is attacked, the predator strikes at the bull's flank to disable it. This natural instinct is the reason the flank strap is so successful at encouraging the bulls to buck higher.
The rider hangs onto the front, or bull rope, during his ride. A bell is attached at the bottom of the rope for weight so the bull rope falls off with the cowboy or when he releases the bull rope.