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,
the DVD series: The Video Encyclopedia of Pool Shots,
and the monthly Billiards
Digest "Illustrated Principles" instructional articles
for more information, see Chapter 4 in The
Illustrated Principles of Pool and Billiards
and Disc II of the Video Encyclopedia of Pool Shots
backhand and front-hand English
How does backhand and front-hand English work?
Backhand English (BHE) and front-hand English (FHE) are aim-and-pivot methods used to adjust one's aim for squirt. For more information and illustrations, see my November '07 article. Also, here's a simple video demonstration of BHE . Here are some more detailed videos on the topic:
This video shows the effects of bridge length and the amount of squirt of the shaft:
NV B.58 - Mike Page's BHE pivot length demonstration
When using BHE, the bridge length must coorespond to the pivot length of the cue, unless you are also compensating for swerve and/or throw.
See also: aim compensation for squirt, swerve, and throw (includes more video demonstrations).
from Patrick Johnson:
BHE = back hand english = setting up for a centerball hit then moving the grip hand (back hand) sideways to apply english and compensate for squirt/swerve at the same time. Works best with higher squirt cues where the "pivot point" is somewhere near the bridge. An approximation that must be fine-tuned by feel.
FHE = front hand english = setting up for a centerball hit then moving the bridge hand (front hand) sideways to apply english and compensate for squirt/swerve at the same time. Works best with lower squirt cues where the "pivot point" is substantially behind the bridge. An approximation that must be fine-tuned by feel.
Parallel English = a bad name ("parallel" doesn't really apply) for simply placing both hands as necessary to apply english and compensate for squirt/swerve. Works with any cue, but is done entirely by feel and can be more of a challenge for some players without the initial approximation provided by BHE or FHE.
All of these are different ways of getting your cue to the same position. Only one cue position will produce the exact shot and spin you want.Backhand english isn't an exact science - where you place your bridge for the pivot changes from shot to shot depending on how much swerve there is in the shot (which depends on shot length, speed, amount of sidespin, elevation of the cue, cloth cleanliness/age, ball cleanliness/age, even humidity). Backhand english can be a useful technique despite all these variables - it will still get you closer to the correct aim adjustment for any shot, but you'll almost invariably have to make some small additional aim adjustment "by feel".
And here's the kicker: it may or may not be a good thing to know about the "by feel" part of backhand english. Most backhand english users believe (or pretend to believe) that it's an exact adjustment for every shot, which allows their subconscious to make the final adjustment without being confused by "too much thinking". Colin Colenso, on the other hand, makes all the adjustments consciously, even mathematically [for more info, see: aim compensation for squirt, swerve, and throw]. You'll have to decide how to do it for yourself.
Personally, I'm somewhere between the two extremes of "totally by feel" and "Colin Colenso total consciousness". I try to think about all the variables as I'm lining up the shot, to be sure my subconscious has all the data it needs, and then I try to let that all go just before I shoot, getting out of the way of my subconscious for the final aim and stroke refinements
from dr_dave:
I'm with you on this one. I firmly believe in having a complete understanding of all of the effects, to help guide the subconscious. Even "aiming by feel" relies on subconscious understanding, IMO. I like using BHE as a starting point, especially for short and/or fast shots with a near-level cue; but I also use knowledge-based and experience-based "feel" to make adjustments to account for shot speed, shot distance, ball/cloth conditions, and cue elevation (although, I try to avoid English like the plague when cue elevation is required ... unless swerve or masse are the only or best shot options).
from Jal:
... Object balls ... are ... 'thrown' by friction with the cueball during the collision in a direction they normally wouldn't go if you look at the geometry alone. This effect is small when the cueball has a lot of topspin or backspin on it as it arrives at the object ball, and can generally be ignored in these cases. If the cueball doesn't have a lot of topspin or backspin, the throw effect is greater and you'll often enough have to compensate for it. Most players learn to do this subconsciously, but it doesn't hurt to be aware of it.
Speed and distance affect how much the 'cueball' swerves on the way to the object ball. And generally speaking (there are exceptions), speed affects how much the object ball is thrown off its geometrically ideal direction during the collision. Higher speeds actually reduce friction between the balls.
I think an easy way to remember how bridge length adjustments affect the shot when using the backhand pivot method to apply outside english (right sidespin when hitting the object ball on its right side, i.e, cutting it to the left), is that with a typical cut shot, moving your bridge hand back will result in a fuller hit on the object ball, i.e., more (exposed) shaft = more object ball.
The above affects the initial direction of the cueball as it leaves the tip. This is called "squirt", or "deflection" by some. As far as the curved path the cueball subsequently follows (swerve), striking high on the cueball (in addition to the applied english) will generally result in more effective swerve (sideways displacement of the cueball as it reaches the object ball), while striking low will produce less. This is for shots with only a modest distance separating the balls. The opposite can be true with large distances. (Striking low produces more swerve overall, but it happens much more gradually. Thus the term "effective swerve.")
Combining these to sort of auto-compensate when applying outside english using the backhand pivot method then, striking high on the cueball = more exposed shaft when pivoting, low = less. And since greater shot speed reduces effective swerve but doesn't affect squirt (practically speaking), greater speed = less exposed shaft, less shot speed = more. Unfortunately, the latter is an inverse relationship, which isn't as neat and as easy to remember as the other ones. I'll leave it to you to work out these relations for inside english (left sidespin when cutting the object ball to the left, i.e., still hitting the object ball on right side).
As you probably realize, these details (and others) are maybe good to be consciously aware of while developing a feel during practice. But the end goal is for all of this to become second nature.
Why do some people like to use inside English on most shots?
First of all, the type of English is usually dictated by cue ball position requirements for the next shot, so inside English will not always be the right choice. Otherwise, here are some possible reasons to favor inside English (IE) when other English is not required (or when no English is required):
For more information, see my February '07 article and the FAQ page dealing with throw.
from Colin Colenso:
Inside english is often useful in taking the CB 2 or 3 rails. Often in these situations it heads for open space into the middle of the table. With a little practice this is quite predictable and leaves a player better next shot options.
For the draw with inside they may be doing this to check (hold) the CB angle off the rail. It may allow them to hit the shot a bit firmer without risking losing the CB, and by hitting it a bit harder, they avoid the risk of leaving whitey too close to the rail.
Also, inside can be very useful in getting the CB down table from say a 3/4 ball shot down the long rail.
Inside has similar throw to rolling follow so long as you don't play it too soft or from too straight on. Advanced players often utilize it. Intermediate players seem to love their OE, whereas advanced players are often weary of it, other than using a touch to gear away the throw, particularly on soft stun shots.
Why are inside-English shots more difficult for some people?
from Patrick Johnson:
It's a combination of things:
1. You use it less often (partly because you're not as good with it).
2. You use it for different (often more difficult) shots.
3. You use different spin with it (usually high vs. usually center or low).
4. You hit it at a different speed (usually harder).
5. It's less self-correcting.
Pay attention to these things while practicing inside and outside shots and you'll get better at inside pretty quickly.
A specific suggestion: pay attention to exactly where your stick is pointing on each shot compared with the CB/OB contact points - as you make and miss shots it will help you see the exact differences in how to aim them (it also helps generally to build accurate "shot memory").
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.
Some people think low-squirt shafts or the types of tip or other things can help you get more spin the the CB, but this is not the case. For more info see here.
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.
from dr_dave:
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.
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.
For general advice on how to aim and pocket rail cut shots, see Section 4.06 in The Illustrated Principles of Pool and Billiards.
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.
For many examples and explanations of how to judge fouls with rail cut shots, see:
NV B.63 - Instruction for pool rules quiz (part 3: rail cut shots)
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.
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.
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 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.