Backhand English

Backhand English (BHE), also called pivot aiming, is a cue sports technique for compensating cue ball deflection ("squirt") and swerve when applying sidespin (English). The player first aligns the cue for a center-ball hit toward the target, then pivots the cue around the bridge hand to move the tip sideways to the chosen contact point on the cue ball. With the bridge at the cue's natural pivot length, the deflection of the cue ball cancels the angular change from the pivot, so the cue ball travels along the intended line despite the sidespin.

Front-hand English (FHE) uses the grip hand as the pivot instead of the bridge hand. Both are "aim-and-pivot" techniques, in contrast to parallel English (PE), in which the whole cue is shifted sideways without a pivot.

History and terminology

The term "backhand English" has been used in cue sports instruction for several decades. Its precise origin is unclear. The technique was analyzed and popularized in modern instructional literature by David Alciatore ("Dr. Dave"), a mechanical engineering professor at Colorado State University, through his technical proofs, videos, and articles in Billiards Digest.

The technique has also been described by authors outside Alciatore's work. Physicist Ron Shepard discussed it in his papers on cue ball deflection, describing a player who aligns the shot without sidespin and then pivots the cue to compensate for squirt.

"Backhand English" is also used colloquially for a stroke swoop, in which the back hand moves sideways during the stroke. As an aim-and-pivot technique, the term instead means moving the back hand before the stroke, after the center-ball alignment is set.

Physics

Squirt

A cue ball struck off-center with sidespin does not travel along the cue's aiming line. It deflects to the side opposite the applied English. This is called "squirt" or "cue ball deflection." Its size depends mainly on the shaft's end mass, the tip offset from center, and the tip shape and size.

Swerve

Because the cue is slightly elevated to clear the rails, sidespin also produces a sideways curve in the ball's path, called "swerve."

On short, fast shots the cue ball reaches the object ball before swerve develops, so only squirt needs compensation and the required bridge length is the cue's natural pivot length. On longer, slower shots swerve develops and partly or fully offsets the squirt, so the effective pivot length for the shot is longer than the natural pivot length.

Natural pivot length

The natural pivot length of a cue is the bridge distance at which a cue pivot exactly cancels squirt, with a level cue or a shot fast and short enough that swerve is negligible. It is a physical property of the shaft, set mainly by its end mass and construction. Reported values for production cues run from about 8 inches (high-squirt cues) to 14 inches or more (low-deflection cues).

To measure it accurately, the shot is struck fast over a short distance with the cue as level as possible, so swerve does not contaminate the measurement.

The natural pivot length differs from the effective pivot length, which includes the combined effects of squirt and swerve for a given speed, distance, cue elevation, and cloth condition. The effective pivot length is always at least the natural pivot length and varies from shot to shot.

The swerve addition to the effective pivot length is set by shot and table conditions rather than the shaft, so the natural pivot length acts as a baseline for a player's pivot lengths: a cue with a shorter natural pivot length gives shorter bridge lengths across the range of shots. Traditional wooden shafts usually have higher end mass and sit at the short end of the range, while many low-deflection shafts sit at the long end. Pivot length follows construction and end mass rather than material alone. Many carbon-fiber shafts are built for low deflection and long pivot lengths, but solid-core carbon-fiber shafts can have end mass and pivot lengths like traditional wood.

Factors affecting effective pivot length

The effective pivot length changes with several variables:

• Shot speed: Slower shots give swerve more time to develop and need a longer effective pivot length. Faster shots suppress swerve and need a shorter bridge, closer to the natural pivot length.
• Shot distance: More distance between cue ball and object ball gives swerve more time to act and increases the effective pivot length.
• Vertical spin: Follow (topspin) brings swerve on sooner than draw (backspin), because the ball reaches rolling sooner. Follow shots therefore need a longer effective pivot length than draw shots of the same speed and distance.
• Cue elevation: More elevation increases swerve. Shots with the bridge on the rail, where the cue is more elevated, produce more swerve than level shots.
• Cloth conditions: Slicker cloth produces less swerve. Worn or humid cloth increases friction and swerve.

Methods of application

Backhand English (BHE)

In its basic form, BHE begins with the cue aligned for a center-ball hit along the target line. The bridge hand is placed at the pivot length appropriate to the shot, and the cue is pivoted around the bridge by moving the grip hand sideways to the chosen tip contact point on the cue ball. The stroke is then delivered straight along the new alignment.

With the bridge at the correct effective pivot length, the cue ball's initial deflection (squirt) and later curve (swerve) combine to send it along the intended line despite the sidespin.

Front-hand English (FHE)

FHE uses the same principle with the grip hand as the fixed pivot. The player aligns center-ball, then shifts the bridge hand sideways while keeping the grip hand fixed, changing the pivot geometry without moving the back hand.

Changing the bridge length

Another approach is to change the physical bridge length for each shot instead of combining BHE and FHE. The player keeps a pure backhand pivot and slides the bridge hand closer to the cue ball for fast, short shots and farther for slow, long shots.

SAWS

The System for Aiming With Sidespin (SAWS), developed by David Alciatore, keeps a fixed bridge length and compensates for shot conditions by combining percentages of BHE, FHE, and parallel English. The bridge length stays the same, and the share of each hand's sideways movement is adjusted for the shot's speed and distance.

Parallel English (PE)

In parallel English the whole cue is shifted sideways so it stays parallel to the original center-ball line, with no pivot. The needed shift depends on the combined effects of squirt, swerve, and throw for the shot.

Self-correcting properties

Bridging at the correct effective pivot length tolerates small stroke or tip-contact errors. If the player means to strike a given tip offset but strikes slightly wider or narrower, the squirt angle and the pivot angle change in proportion. With the bridge anchored at the pivot point, the two errors tend to cancel, keeping the cue ball on or near the intended line.

Throw compensation

BHE and related pivot methods send the cue ball to the ghost-ball position but do not account for throw, the sideways deflection of the object ball from friction in the ball-to-ball collision. Throw is compensated separately by adjusting the aim line.

Mechanism of throw

At contact, friction exerts a sideways force on the object ball and pushes it off the geometric impact line. The direction and size of throw depend on:

• The cut angle between the cue ball's path and the object ball's target line.
• Shot speed: slower shots throw more.
• The spin state of the cue ball at contact: sidespin, topspin, and backspin all affect throw.
• The friction between the balls, which varies with cleanliness, humidity, and wear.

Gearing English

For a given cut angle and speed there is an amount of outside English, called gearing English, at which spin-induced throw exactly cancels collision-induced throw and net throw is zero. With gearing English the object ball travels along the line of centers and no throw compensation is needed.

Compensation direction

When the sidespin differs from the gearing amount, throw compensation is needed:

• With outside English below the gearing amount, or with inside English, the object ball is thrown in the direction of collision-induced throw and the player aims slightly toward the spin side to compensate.
• With outside English above the gearing amount, spin-induced throw exceeds collision-induced throw and the object ball is thrown the other way, reversing the compensation.

Spin changes as the cue ball travels. Vertical spin decays toward natural roll while sidespin is largely kept, so throw compensation must use the spin state at contact, not the spin applied at the tip.

Calibration

The effective pivot length depends on the cue, the table, and the shot, so it is found by direct measurement at the table rather than assumed. Calibration determines, for each shot condition, the bridge length at which the cue ball replaces the ghost ball despite the applied sidespin.

The instructional literature describes two special-case measurements. Swerve has no time to develop on a fast, short shot, so a measurement under those conditions gives the cue's natural pivot length, the value used to compare deflection across shafts. A slow, long shot lets swerve develop fully, and comparing this measurement with the fast short-shot measurement shows how much extra pivot length swerve adds under those conditions.

Comparison of methods

Method	Pivot point	Bridge length	Compensation approach
Backhand English (BHE)	Bridge hand fixed	Variable or fixed	Pivot around bridge hand
Front-hand English (FHE)	Grip hand fixed	Fixed	Pivot around grip hand
SAWS (BHE + FHE combo)	Both hands move	Fixed	Percentage-based hand shifts
Parallel English (PE)	None (parallel shift)	Fixed	Lateral cue shift

See also

• Cue sports techniques
• Cue sports
• English

External links

• Dr. Dave Billiards: Back-Hand English (BHE) and Front-Hand English (FHE)
• Dr. Dave Billiards: Natural Pivot Length
• Squirt – Part IV: BHE, FHE, and pivot-length calibration (Billiards Digest, November 2007)