Ball Inflation and the Rebound Height Standard

[assignmentmaker]

Rule 1-12-2 says: "The ball shall be inflated to an air pressure such that when it is dropped to the playing surface from a height of 6 feet, measured to the bottom of the ball, it shall rebound to a height, measured to the top of the ball, of not less that 49" when it strikes on its least resilient spot, nor more than 54" when it strikes on its most resilient spot.

My impression is that basketballs nowadays are overinflated more often than not, perhaps because electric pumps make inflating too easy. When overinflated, they bounce higher than the standard calls for, and - of concern to those fond of a smooth, easy game - they don't go in as often as they otherwise might.

I have always taken it that 'its' in rule 1-12-2 references the resilience of a spot on the floor, not a spot on the ball, though it could mean the ball . . . Let's assume 'its' refers to the floor and that the floor is uniform. Player height (just considering guards), however, isn't uniform, however, especially average player height on a genderal basis.

I find that a girls basketball that rebounds to the high end of the 1-12-2 drop test range is, for many high school varsity girls games, too bouncy, coming up too high too easily, getting away from the players. The situation is only worse for lower level games.

Secondarily, as alluded to above, when the ball is overinflated, it rockets off the rim. The shooter's touch that might give a ball grazing the front rim a chance is swamped by the bounciness of the ball. The game is often more ragged.

I now come complete with a needle. Where I officiate, the game ball, more often that not, is one of the balls the players are warming up with. I test a bunch of home team balls and, if I find a nice round one (throw it up spinning and look for any wobble), I'll adjust its inflation as needed so that the ball rebounds closer to a genderally adjusted norm. Deflating the ball isn't as easy you might think. With the needle at full, moistened insertion, something in the design of the valve appears to inhibits air flow back out; kneeling with a knee on the ball can speed the process. And, if the crowd thinks you're praying, they should respect that . . .

There's probably an inherent differential in pressure that should be specified for boys and girls balls solely because of the different diameters. The smaller ball will be inherently stiffer, though, it's true, lighter - all given the same material. But that's a story for a Journal of Basketball Science thread.

Yuh think?



[Edited by assignmentmaker on Jan 28th, 2006 at 08:38 PM]

[blindzebra]

For the love of God get a life.

Hold the ball over your head, drop it, lower your arm into the hammer and if the ball comes back up close to your elbow we are good to go.

Nobody, and I mean nobody should be confused about this topic.

[canuckrefguy]

Originally posted by assignmentmaker
Rule 1-12-2 says: "The ball shall be inflated to an air pressure such that when it is dropped to the playing surface from a height of 6 feet, measured to the bottom of the ball, it shall rebound to a height, measured to the top of the ball, of not less that 49" when it strikes on its least resilient spot, nor more than 54" when it strikes on its most resilient spot.

My impression is that basketballs nowadays are overinflated more often than not, perhaps because electric pumps make inflating too easy. When overinflated, they bounce higher than the standard calls for, and - of concern to those fond of a smooth, easy game - they don't go in as often as they otherwise might.

I have always taken it that 'its' in rule 1-12-2 references the resilience of a spot on the floor, not a spot on the ball, though it could mean the ball . . . Let's assume 'its' refers to the floor and that the floor is uniform. Player height (just considering guards), however, isn't uniform, however, especially average player height on a genderal basis.

I find that a girls basketball that rebounds to the high end of the 1-12-2 drop test range is, for many high school varsity girls games, too bouncy, coming up too high too easily, getting away from the players. The situation is only worse for lower level games.

Secondarily, as alluded to above, when the ball is overinflated, it rockets off the rim. The shooter's touch that might give a ball grazing the front rim a chance is swamped by the bounciness of the ball. The game is often more ragged.

I now come complete with a needle. Where I officiate, the game ball, more often that not, is one of the balls the players are warming up with. I test a bunch of home team balls and, if I find a nice round one (throw it up spinning and look for any wobble), I'll adjust its inflation as needed so that the ball rebounds closer to a genderally adjusted norm. Deflating the ball isn't as easy you might think. With the needle at full, moistened insertion, something in the design of the valve appears to inhibits air flow back out; kneeling with a knee on the ball can speed the process. And, if the crowd thinks you're praying, they should respect that . . .

There's probably an inherent differential in pressure that should be specified for boys and girls balls solely because of the different diameters. The smaller ball will be inherently stiffer, though, it's true, lighter - all given the same material. But that's a story for a Journal of Basketball Science thread.

Yuh think?



[Edited by assignmentmaker on Jan 28th, 2006 at 08:38 PM]

Okay, that was twice as long, and half as clear

[Camron Rust]

Are you reading physics books after having a too many beers again?

The height of a bounce is relative to the height of where it started. The matter of how high is bounces for girls as compared to boys is irrelavant since the bounce is directly proportional to the height from which it is dropped/dribbled...the player's height...which will be shorter for most girls. It all just works out.

Also, I don't know what balls you're having trouble getting air out of since I've never had trouble doing so....insert needle and whoosh, it's doing it all by itself (unless you're trying to make a pancake).

[Camron Rust]

Originally posted by canuckrefguy
Okay, that was twice as long, and half as clear

And that's by metric standards too! In the US, it's be 6.235 times as long and 0.23895 times as clear.

[Cyber-Ref]

assignmentmaker: But that's a story for a Journal of Basketball Science thread.

Next thing you know is we'll check the torque on the rim flange bolts !!

[JCrow]

Assignmentmaker,

Don't let these guys get you down. I too have had ball pressure issues this year. But....in the Youth League where I Ref....I find that they are usually too under-inflated. The kids have trouble dribling because they have to slam the ball down to get it to return. (I carry my own pump & needle, now.)

Regarding the bolt/torque comment - 3/4" - A307 High Strength Bolt - 375 ft-lbs. - careful not to jerk the torque wrench as it causes an inaccurate reading.

[assignmentmaker]

Originally posted by Camron Rust
Are you reading physics books after having a too many beers again?

The height of a bounce is relative to the height of where it started. The matter of how high is bounces for girls as compared to boys is irrelavant since the bounce is directly proportional to the height from which it is dropped/dribbled...the player's height...which will be shorter for most girls. It all just works out.

Also, I don't know what balls you're having trouble getting air out of since I've never had trouble doing so....insert needle and whoosh, it's doing it all by itself (unless you're trying to make a pancake).

Good point! True enough (for a theoretical ball!).

But the height of rebound when the ball is pushed to the floor is proportional to both the acceleration of gravity component and the player-push component, is it not? While girls, as a class, are not as muscular as boys, when they push hard on the ball you can see the effect I am alluding to. Perhaps, as a class, they are less proportionally stronger than proportionally shorter. Now the ball is coming up faster and they are closer to it.

Also, now that I think about it, perhaps the impedance match of the collision - ball on floor - creates a non-linear factor in how the ball rebounds. The more fully it's pumped, the less lossy the collision is.

In any case, I'm surprised and interested that others don't think there's a problem.

[bob jenkins]

Originally posted by assignmentmaker
In any case, I'm surprised and interested that others don't think there's a problem.

If by "problem" you mena general overinflation of the basketball, I agree -- but I don't think it's worse this year than any other year. I'd say 80% of the basketballs I test as R need to have air taken ouit -- both boys and girls basketballs. I've carried a needle for years.

Only one ball that I've tested was too low.

[assignmentmaker]

Originally posted by bob jenkins

If by "problem" you mena general overinflation of the basketball, I agree -- but I don't think it's worse this year than any other year. I'd say 80% of the basketballs I test as R need to have air taken ouit -- both boys and girls basketballs. I've carried a needle for years.

Only one ball that I've tested was too low.

I don't think it's so much worse this year as it has been trending worse for years as a function of two things: cheap electrical pumps (every AD has one) and increasing lack of attention to detail (let the kid pump up the balls).

[canuckrefguy]

Maybe it should be a Point of Emphasis....

[MichaelBlackbur]

For about 6 bucks get the 1ump.com "Game Ball Judge, Basketball." It takes about 10 seconds to use it and then you know the ball is right. Bet the AFC Championship Refs wish they'd done something this simple before last week's game.
https://www.1ump.com/

[Rich]

Originally Posted by APG

This is a nearly 9 year old thread. Please don't revive old threads.

Well, I can always be "in before the lock" so I'll post two last thoughts.

(1) If you are thinking about having one of those game ball measurers as an official....don't, unless you want to be seen as a Poindexter without one shred of common sense.

(2) Bob's 80% estimate is probably a bit on the low side. I take air out almost every night. Maybe it was 80% back in 2006. I can't remember that far back.

[Welpe]

Originally Posted by MichaelBlackbur

Bet the AFC Championship Refs wish they'd done something this simple before last week's game.

Yep that's exactly how you check inflation on footballs.

[Rich]

Originally Posted by Welpe

Yep that's exactly how you check inflation on footballs.

I'm picturing the typical HS football official bouncing a ball and seeing if it bounces 49 to 54 inches...and then chasing it down and doing it again. For some reason this has me (literally) LOL.

I'm almost ready to sell my latest officiating innovation -- it's a 6-foot-long stick that officials can carry on the floor to use in those tricky closely-guarded situations.

Originally Posted by APG

This is a nearly 9 year old thread. Please don't revive old threads.

Normally, I'd agree. But the ball-inflation tool wouldn't have been posted otherwise and, well, it's made my day.

I'm tempted to buy a few as gag gifts for my association banquet. And then act like they are serious tools no official should be without.