English

 Dr. Dave's answers to frequently-asked questions (FAQs),
mostly from the BD CCB and AZB discussion forums

maintained for the book: The Illustrated Principles of Pool and Billiards
and the monthly Billiards Digest "Illustrated Principles" instructional articles

for more information, see Chapter 4 in The Illustrated Principles of Pool and Billiards

backhand English

How does backhand English work?

Backhand English (BHE) is an aim-and-pivot method used to adjust one's aim for squirt. For more information and illustrations, see my November '07 article.

See also: aim compensation for squirt, swerve, and throw.

maximum English

How can I get more English on the cue ball?

In general, to get maximum English, prepare and chalk a good tip, and hit the cue ball as far left or right of center as you can without miscuing. See my October '05 article for more info. A striped ball can useful for practice because the width of the stripe is usually half the ball's diameter, which corresponds to the typical miscue limit (half the ball's radius away from center). See my July '06 article for more info.

Now, to achieve the most effect from sidespin (i.e., get the most rebound angle change off a rail), you want to use a drag shot where you hit enough below center to create stun at rail contact. The problem with hitting below center is that you must decrease the amount of sidespin (tip offset) a little. However, because the drag action slows the cue ball while retaining most of the sidespin, the rebound angle will be larger.

from Jal:
Sidespin (english) is used on the majority of shots to either control how the cueball comes off a cushion, or to reduce object ball throw (with outside english). In both cases, it is the amount of spin relative to the speed of the cueball that is important - the spin/speed ratio. This is governed nearly totally by tip offset, ie, how far from center tip contact is made. Cue speed and weight have a very slight effect. The heavier and faster the cue, the greater the spin/speed ratio (very slightly).

The factors that govern absolute spin rate, as with force follow and draw shots, have been mentioned (tip offset and cue speed), but just to add this. For any particular player, there is an optimal cue weight, one that produces the most spin, for each particular offset. No one cue will work equally well at all offsets for that player. But the good news is that over a rather broad range of cue weights, there is very little difference between them as far as cueball response. (The reason for this has to do with with the inertia of the player's arm.) Nevertheless, as a general rule, a heavier cue is more efficient at centerball, while a lighter one is more efficient away from centerball (in theory).

I would think that harder tips would be more efficient than softer ones, but some tests done by another poster here, Mike Page, suggest that this might not be the case, that they may be about the same. This is a part of cue efficiency as a whole. I suspect that there is very little difference between the "best' and "worst" cues as far as overall efficiency is concerned.

In brief, the principle factors (and virtually the only factors) are tip offset for spin/speed ratio, and tip offset plus cue speed for absolute spin rate. Having a well-chalked tip in good condition is important too, of course, as it determines how far from center you can hit.

my reply:
Excellent summary!

For people who use "tips of English," tip shape can also affect the amount of spin they apply. See my January '08 article for illustrations and explanations.

For people who want to see the math and physics behind many of Jal's statements above, see TP A.30.

 

outside English

Should I use outside English to reduce the effects of throw?

If the exact amount of outside English (OE) (called "gearing" OE) is used for a given cut angle, the will be no throw (see HSV B.30, HSV B.33, and my January '07 instructional article for more info). Throw can vary with cut angle, speed, vertical plane spin, and ball conditions, sometimes resulting in an excessive and unanticipatable amount of throw, called "cling." So it makes sense to try to eliminate all of these uncertainties if possible. But it can be difficult to have a feel for the exact amount of OE to use for different shots; although, this feel can probably be developed fairly easily. As long as one is just a little off with the amount of OE, the amount of throw could still be small enough to be a non-factor. (If people want more information, illustrations, and examples of everything mentioned in this paragraph, see my October '06 through February '07 instructional articles.

So eliminating throw as a variable is a good thing, but the problem is that English also introduces squirt and swerve. Now, if the cue stick is as horizontal as possible (i.e., not elevated), and firm speed is used, swerve won't be much of a factor (but it can be in many pool shots). Concerning squirt, a low-squirt cue can help minimize the effect, and backhand English (or front-hand English) techniques can be used to help compensate (e.g., see NV A.19). However, for many shots, squirt and swerve effects might require significant compensation.

If cling is not much of a concern, and a player has a good feel for throw effects, maybe throw compensation (with aim adjustment) could be more straightforward than squirt/swerve/gearing OE compensation.

The other problem with relying on gearing OE to eliminate throw is that OE might not be appropriate for the shot, based on position play requirements (e.g., to get position on the next shot, inside or no English might be required instead). So it seems one needs to able to compensate for throw anyway to be able to have a full arsenal of shots. Now, if you don't need English for position on a particular shot, this is a moot point.

One thing is for sure: OE (or any English) is probably not the best choice with thin cuts, where aiming precision is key. Here, a center-ball hit will result in the best accuracy.

from Bob_Jewett:
It's usually impossible to plan a run-out using only outside English, as has already been mentioned. You might have "English freedom" on 20% of your shots. If you're not going to hit a cushion or just barely bounce off a cushion, your side spin doesn't matter, so you are free to use what you will. If you have very good speed control and pattern planning, you might use the cushion on less than half your shots.

The main up-side in using outside English is that it eliminates throw and skid which come from ball-ball friction at the point of contact between the cue ball and object ball. With those eliminated, you are not at the mercy of changing frictional conditions on the shot.

The problem with using this "smooth rolling across the object ball's surface" technique is that it requires a lot of skill and experience to get right. The amount of outside required depends on the cut angle, the distance to the ball, and the amount of draw/follow. As has been pointed out by Dr. Dave, Ron Shepard and others, if you get it wrong by a little the shot can go wrong by a lot.

I think the main factor is on skids. This is also called "cling" and in snooker-playing regions "kick." I think the best name for it is "bad contact." In any case, it seems to be due to chalk at the contact point of cue ball on object ball and it causes large amounts of throw. Some players don't even realize that skid exists and think that when people complain about getting a skid/kick/cling/bad contact they are just trying to make excuses. Skids can happen on maybe 1 shot in 50 to 500 depending on conditions and the sort of shots taken.

So, where is this all going? If a player just flat out misses 30% of the shots he shoots at, he's got no reason to take special, complicated precautions to avoid a 1% problem. At that level he should be working on bringing his stick straight through the middle of the cue ball with maybe a little follow or draw. Nice and smooth and not too hard. Such a player has only a dim notion of squirt, swerve and throw, and probably no knowledge of skid.

On the other hand, if you're Rempe or Sigel or Hohmann, and on a good day you miss only one time in 200 shots attempted, you can't afford to have the object ball skidding off randomly one time in 100.

So the bottom line is that whether you should try to use outside English on the fraction of shots that allow the freedom to use it may well depend on how well you play.

rail cut shots

How can I control CB direction and still pocket the OB with a rail cut shot?

The answers can be found in HSV A.128-A.141. They are also presented with graphics and narration in the excerpts of my HSV DVD. Check them out. I've listed the clips in order based on how far down-table the cue ball travels. The object ball is pocketed in all of the clips from two diamonds up from the corner pocket.

spin axis "flip" demonstration

When you hit a striped ball with bottom-left English, and the stripe is initially aligned with the English direction, the stripe appears to "flip" during the shot. How does this work?

The following video demonstrates and explains (with the help of high-speed video) how the spin axis changes as drag converts bottom spin to forward roll, while English persists. Here it is:

NV B.10 - Drag spin loss and English persistence

If you not able to view YouTube videos, an alternative (lower quality) version can be viewed here.

Check it out and give it a try. It's a cool visual demo.

"Spin," "slide," and "roll"

Can a cue ball have more top spin than actual rolling speed?

Yes, about 25% more. For illustrations and more information, see my October '05 instructional article.

This is often much confusion and misinterpretation about the various terms related to spin and English. Here's a good summary of definition:

I have a good illustration of all of these cases in Diagram 5 of my April '04 instructional article.

"tips" of English

What does it mean when somebody says "one tip of English"?

My January '08 and July '06 articles illustrate and explain "tips" of English. "One tip" of English corresponds to shifting the cue one tip-width away from the center of the ball. Because the actual tip offset for "one tip" of English depends on both the tip size and shape, I prefer specifying the amount of English as a percentage instead (100% for maximum English at the miscue limit, 50% at half of maximum).

when to learn

When should someone start learning English (sidespin)?

I don't think a person should spend much time with English until his or her fundamentals and stroke are solid. When deciding to use English seriously, a person should also start learning about all of the effects that need to be taken into consideration. For more info, see aim compensation for squirt, swerve, and throw.

from Bob_Jewett:
As far as the basic knowledge part, I think it is important to discuss that before the beginner starts using side spin. I point out how the side spin can be useful but at the same time I show five major problems with using it: squirt, swerve, throw, miscues and cling/skid/kick/bad contacts, and some of the details of those problems. Most beginners do not fully understand those problems when first introduced to them, but I want them to be aware that problems exist.