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[Psi]

It is really complicated to do the analysis, and there are lots of incomprehensible academic papers about this and the related question of how to design a baseball bat.

But, the very simplest explanation uses conservation of momentum (=mv) , which applies to all bat - ball collisions, plus the assumption of an inelastic collision, which causes loss of kinetic energy (=0.5mv^2) during the collision. Solving these equations show that a heavier bat makes the ball go faster after hitting it, see e. g. Wikipedia page on inelastic collisions. But only for the same swing speed, and we all know it is harder to swing a heavier bat fast. But, the equations also show that the ball speed depends on a coefficient that can be thought of as the pinginess of the bat, so that's likely to be just as important.


So that's why we all have a different ideal bat weight, depending how strong and quick we are, and a pingier bat is always better.

Anyway, ignore if this makes no sense, but it does rely on physics and is a bit more complex than 'f=ma' alone.

[InternalTraining]

...But, the equations also show that the ball speed depends on a coefficient that can be thought of as the pinginess of the bat, so that's likely to be just as important.
So that's why we all have a different ideal bat weight, depending how strong and quick we are, and a pingier bat is always better.

Do you have more info on this? I don't mind "incomprehensible academic papers".

My observation is that, when testing a bat and bouncing a ball in your kitchen,  it is not enough that ball bounces off the bat high but also how fast it bounces off the bat towards the ceiling. My better bats produce a ridiculous, springy rebound off the face. We use the term "pinginess" very generally but what I am describing is "springiness" () of the bat. More springy the rebound, better the bat.

[Chompy9760]

My observation is that, when testing a bat and bouncing a ball in your kitchen,  it is not enough that ball bounces off the bat high but also how fast it bounces off the bat towards the ceiling.

How high it bounces is directly related to how fast it rebounds from the face.  The only other factor is gravity which is constant, so essentially that's just two ways of interpreting the exact same thing.

[Psi]

Yes, the only thing that matters is the speed of the ball off the bat. Any changes to this are the result of hitting it in a different place on the bat surface, or using a different hand action to make the hit. Probably how you are holding it can make a difference too, but there's also an argument that says it makes no difference at all how tightly you grip the bat, as long as it follows through on the shot without major slowing down. I'll look out some of the papers I have spotted.

[JK Lewis]

Maybe one of you brainiacs could build a bat testing robot in your garage, in your spare time. 

[Chompy9760]

Something like this ?
https://www.youtube.com/watch?v=0YVWJ9CqNJA

It's a pretty good replication of the real thing.  I would like to have seen more bats tested!

[Wickets-then-runs]

Ive gone from 2.8 throughout my career to 2.12 to 2.14 in my my mid-late 40's as ive found that as my eyes and reflexesdrop off, i need to slow my bat swing and focus on the ball/swing.