Angles guide
The hand: overhand, sidearm, underhand
Your hand is a surface too. The spin a ball carries comes from how your hand drags across it, and where on the ball you meet it.
The ball turns the way your hand drags it
When your hand meets the ball it pushes it and, if the hand is moving across the ball's surface as well as into it, drags that surface along. The ball turns the way its back is dragged:
- Brush up the back of the ball (the hand rising through it): topspin.
- Brush down the back of the ball (the hand falling through it): backspin.
- Brush across it: sidespin. Drag the back of the ball to the left and its front turns right, and the other way round.
- A hand that goes straight through the middle of the ball with a flat face puts little spin on it.
Above or below the centre, inside or outside
Meeting the ball off its centre works the same way. Meet it above its centre (your hand's face tilted down) and the ball goes down with topspin: in the model, a 15° tilt sends it about 16° down. Meet it below its centre (face tilted up) and it goes up with backspin, about 16° up. Meet it on the inside or the outside and it goes off to the other side with sidespin. A rising or falling hand with a square face changes the launch only a little (about 4° in Figure 7), so a brushing hand adds spin without much change of direction, while a tilted face changes the direction and the spin together.
Gloves, sweat and how firm your hand is all change the grip, so the amount of spin differs from player to player and from day to day. The direction does not.
Overhand, sidearm and underhand
The stroke does not decide the spin by itself: the hand's path through the ball does. Each stroke makes some paths more natural than others, so these are tendencies, and coaches teach them differently.
- Overhand: the hand usually comes down through the ball, which tends to give backspin. A player who rolls the hand and wrist up and over the top of the ball can give it topspin instead.
- Sidearm: the hand sweeps across the ball, which tends to give sidespin, often mixed with some topspin or backspin depending on whether the hand is rising or falling. Many players cup the hand or curl the fingers round the ball to drag it across on purpose; this is usually called a hook.
- Underhand: the hand usually rises through the ball, which tends to give topspin. An open-palmed scoop that goes under the ball tends to give backspin.
Then use the rule from the spin page: a backspin ball is pulled down off the front wall and comes out with topspin for the floor; a topspin ball kicks up off the front wall and comes out with backspin for the floor; sidespin kicks the ball sideways off the front wall, against the way it bent in the air.
High contact and low contact
Where you meet the ball above the floor matters even with no spin at all. To reach a low spot on the front wall, a ball struck from high up has to travel downward, so it arrives steeper and comes off the wall heading down more steeply. In Figure 8 the two balls meet the wall at the same spot: the one struck 0.5 feet off the floor first lands about 8 feet out and hops about 1.0 feet high; the one struck from 6 feet lands nearer, about 5 feet out, but hops higher, about 1.9 feet.
That is why the low shots that roll out are usually struck low, near the floor, with a flat path: the ball meets the wall nearly level and stays low after it. A high contact gives the ball a steeper path, which suits a ball you want to come down near the wall and then sit up, or a shot aimed high on the wall.
Next: worked shots.