How fast is this table?

[Jal]

...In my version, lag the cue ball from one diamond right of center on the head rail and placed two diamonds towards the foot rail (usual lag shot). Start the stop watch when the CB hits the bottom rail. There is a noticeable “thunk.” The CB should come within one inch (or so) of the head rail on its return and it should stop on it’s own.

What the test is really trying to measure is 1/Ur where Ur is the coefficient of rolling resistance. Since the ball doesn't begin rolling until approximately 5" from the foot cushion on a lag speed shot (this is dependent on the coefficient of sliding friction Us), it would be more accurate to start the clock at least 6" from the cushion and then measure the distance it takes to stop from there. But, in all truth, why bother?

At any rate, I can't see that your lag method is any different from the one described earlier. The adjustment factor (98/d) simply relieves you of the necessity of making a perfect lag, and doing it on a 9' table. As I mentioned, you can start the cueball from anywhere, although players should generally have a better feel from the standard lagging position.

On a 9’ competition table this should take about 7 seconds. Each second longer implies the CB will be one diamond slower than a competition table. Each second faster suggests that the table will be one diamond faster than a competition table.

I'm probably reading this wrong, but if it takes longer than 7 seconds for a perfect lag on a 9' table, the cloth is faster then 100. If it takes less than 7 seconds, the cloth is slower.

Actually I like both methods, the ball drop is quite easy to do and you can get a quick feel for the current CB speed given humidity, heat etc.

Agreed...a useful suggestion.

...People talk about the idea that you just have to play to get a feel for a table but I wonder how many people knew that CB speed is nearly one diamond different from the head and from the foot rail on some tables.

This is a surprise if it happens with Simonis or any non-napped cloth. Tables not level?

Jim