Should I use outside spin or english to reduce the effects of throw (i.e., “spin the ball in”)?
For the long answer, see everything below. Here are the short answers:
Yes, if conditions are clingy (old, dirty balls with lots of chalk marks) and/or you are good at adjusting your aim for squirt and swerve, and you are good at judging the “gearing amount” of outside spin.
Although, spin is sometimes useful to help hold the CB for position.
If the exact amount of outside english (OE), called gearing outside english, is used for a given cut angle, there will be no throw. This can be useful in play when cling/skid/kick is a concern (e.g., under dirty and/or chalk-smudged ball conditions). Here’s a good video demonstration of the effect:
and here are some others:
- NV B.86 – Cut-induced throw (CIT) and spin-induced throw (SIT), from VEPS IV
- HSV A.142 – Vernon Elliott cross-side bank with chalk on the object ball to increase throw and spin transfer
- HSV B.30 – Cut-induced and spin-induced throw and spin transfer
The “gearing” outside english handout and the following video, from Vol. I of How to Aim Pool Shots (HAPS), demonstrates how to use the 40% rule (see below) to aim shots with “gearing” outside english to eliminate cut-induced throw:
For more information, see “HAPS – Part III: Gearing Outside English,” (BD, January, 2015). It can be difficult to have a feel for the exact amount of OE to use for different shots, even using the 40% rule; although, this feel can probably be developed fairly easily over time and experience. As long as one is just a little off with the amount of OE, the amount of throw can still be small enough to be a non-factor.
Diagram 2 in “Throw – Part VI: inside/outside english” (BD, January, 2007) shows how the amount of sidespin required for “gearing” OE varies with cut angle. Gearing OE is possible even with a 90° cut. And it is even possbile to throw the OB with spin-induced throw (SIT) at cut angles close to 90° (see impossible cut shots for examples).
Again, if the “gearing” amount of outside english is used, there will be absolutely no throw, and the OB will head exactly in the “line-of-centers” direction. Below is an illustration of an easy way to visualize how much tip offset is required to create a gearing amount of outside english (see TP A.26 for the derivation). The technique is called the 40% rule. Here’s how it works: If you imagine or use your cue to visualize the line through the OB to the pocket, that gives the “line of centers.” If you parallel-shift this to the CB (the red line in the diagram), that defines the “line-of-centers” point on the CB (the red dot in the diagram). The tip contact point must be a little less than half (2/5 or 40% to be precise) of the distance from center ball to the “line-of-centers” point to create “gearing” outside english.
With long, slow, follow shots, you must apply extra sidespin since some will be lost on the way to the OB. And on shots with significant drag action (e.g., draw or stun shots), where most or all of the backspin wears off on the way to the OB, less sidespin is required since the drag action increases the effect of the sidespin. For more info, see the drag shot effects resource page.
An alternative way to determine the gearing amount of outside english is to take 80% of 1 minus the ball-hit fraction. For example, for a 1/2 ball hit (0.5 or 50% ball-hit fraction), the gearing amount of english is 0.8 (1 – 0.5) = 0.4 [alternatively, 80% of (100% – 50%) = 40%]. This works for all ball-hit fractions. For more info, see TP A.26.
Using gearing outside english to eliminate throw as a variable is a good thing (when outside english is an acceptable choice), 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 back-hand english (or front-hand english) techniques can be used to help compensate. However, for many shots, squirt and swerve effects might require significant compensation. Many factors and effects need to be considered when using english, per the list available here: english effects.
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.
If cling is a concern (e.g., if the balls are old, worn, and very dirty with chalk smudges; or if you are pro, where cling on one shot can mean the difference in a match), OE might be appropriate for trying to eliminate throw and possible cling; but you need to be able to judge the required amount of english for all cut angles and be good at judging and compensating for squirt and swerve.
A problem with trying to eliminate throw with gearing OE is that the amount of throw is very sensitive to the exact amount of english when you are close to the “gearing” amount, especially with a stun shot. Therefore, the amount (and direction) of throw can vary quite a bit with small misjudgments and inaccurate application of the gearing amount of english. As demonstrated in HSV B.33, if you have more than the “gearing” amount, the the OB will throw in the direction of the spin (SIT: spin-induced throw); and if you have less than the “gearing” amount, the OB will throw in the cut direction (CIT: cut-induced throw). An argument can actually be made that using inside english is a better approach for dealing with throw. For information about how “gearing” english changes with cut angle, and for lots of illustrated examples, see “Throw – Part VI: inside/outside english” (BD, January, 2007) and “HAPS – Part III: Gearing Outside English,” (BD, January, 2015).
Also, OE might not be appropriate for a given 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.
Outside english can certainly be appropriate when trying to hold the cue ball (sometimes). For more info, see: holding the cue ball.
One thing is for sure: OE (or any english) is probably not the best choice with long-distance thin cuts, where aiming precision is key. Here, a center-ball hit will result in the best accuracy and consistency.
The 40% or 2/5 rule for gearing spin also applies to the amount of spin required to create perfect natural running english on kick shots. Here’s an illustration from Patrick Johnson (from AZB post) showing how this works:
from Bob_Jewett (in AZB post):
Outside english is useful for reducing skids and partial skids. I think the usefulness of outside depends on the level of the player and how often skids occur. If an intermediate player misses 15% of their shots and the ball skids 1% of the time, outside might reduce the skids to 0.1% and increase the misses to 20%.
For a Sigel, Varner or Rempe who misses 2% of the time, getting rid of the bad contacts can give a significant benefit if it doesn’t screw up their pocketing percentage. I think this is what Sigel was getting at. A skid on a simple shot can make it miss. A little outside is not an aiming problem for him so his basic pocketing percentage will not be reduced.
You don’t have to have perfect gearing outside for this technique to work. It only has to be enough outside that the balls are gearing by the end of the ball-ball contact. In that case, the amount of friction between the balls stops being a factor in the cut angle.
from dr_dave (in response to Bob’s last paragraph above):
I don’t agree with the last statement in general. Consider an outside-english cut shot where the CB and OB would normally gear together during the hit (after sliding ceases) If the amount of outside were different, it is possible the balls would not gear before separation. In this case, cling/skid/kick would definitely cause more throw than normal (because added friction does make a difference when the balls don’t normally gear together). Only when the amount of outside english is very close to the gearing amount do small changes in the amount of outside result in the same changes in throw (because the CB and OB would gear together before separation regardless of the extra friction or not).
from Bob Jewett (in response to dr_dave’s reply above, with total agreement from dr_dave):
Skid/cling/kick can only occur on shots where for normal friction the cue ball is still slipping on the object ball at the end of ball-to-ball contact. If you add extra friction, there will be more throw than for a normal shot.
A conclusion from this is that there is a range of spins close to gearing that can’t produce skids. The throw for this range is both to the left and right of the CB-OB line of centers at contact.
A further conclusion is that stun shots without side spin up to about a 20-degree cut will not skid. This is because that is the range for which the balls will achieve gearing by the end of contact for normal values of ball-ball friction.
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.
from Patrick Johnson:
I believe the main difference between using inside and outside spin is familiarity. We naturally use outside spin more because (1) the places we want the CB to go are more often in the outside spin direction (because we’re usually shooting into a corner) and (2) we can usually hit more softly with outside to move the CB the same distance (because the natural carom angle is usually in the outside spin direction).
This built-in preference for outside spin reinforces false feelings like the “helping english” and “self correcting” myths. In fact, since throw tends to correct for squirt but throw is reduced with outside spin, you have to adjust your aim more with outside than with inside, and a shot with “gearing” english is more sensitive to small spin errors.
from Mike Page (in AZB post):
I’ll explain what I don’t like about the equator hit with a twist of outside.
The motivation, I think, is to get a more predictable and consistent result by trying to eliminate throw. That is, if that slight twist provides just enough outside spin to balance the cut-induced throw, the ball surfaces don’t slide across one another at all and there is no throw. If successful, then it doesn’t matter whether the balls are dirty/sticky or clean and waxed— same aim, same result.
But there is a devil in the details, and sometimes it is better to embrace your familiar devil friend.
Let’s say you are on a putt-putt course that has a straight slightly raised ridge down the center, and the goal is to predict as accurately as possible the final resting place of your ball. If you putt right of center, the ball will curve a bit to the right, and if you putt left of center the ball will curve a bit to the left. The details of the curving depend on how hard you hit the ball, and that’s annoying.
You reason that if you hit straight along the top of the ridge, your ball doesn’t curve at all and you’ve removed the dependence on speed. That sounds great, but it comes at a cost. The cost is if you are NOT perfectly straight, the outcome by missing slightly to the left is way different from the outcome by missing slightly to the right. So while you have reduced the speed-dependence to zero with your plan, the cost is you have raised the SENSITIVITY of the final outcome to small errors. It is harder to get a decent prediction of the final resting place of the ball.
The equator hit of the cueball with the slight outside twist is putting along the ridge. While it’s true the perfect twist is lovely, the outcome difference between slightly too much twist and slightly too little is big.
I’m a fan of purposefully putting to the right of the ridge. In this case that’s hitting along the vertical center. This means you live with the cut-induced throw that makes the aim a little different for dirty and clean balls. When you add a touch of high or low, you are reducing the amount of cut-induced throw (because the broom swipe is largely up or down and less sideways) making the dirty ball and clean ball aim close to the same.
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