I will try to participate more when the topic is worthy, and time allows.
We have had a national epidemic of bottom arming and over gripping for almost 20 years. The results of this epidemic have been costly to our sport. Since the height a vaulter ultimately achieves is a combination of grip height and push-off, I felt compelled to use Tim's data as an example. In the future we are better off to teach our beginners the value of taking off clean and swinging, before we teach them to stick the bottom arm and raise the grip.
Thanks!

~jan~