Good advice Tom ... but to just add a couple things to it ...
tsorenson wrote: Many times a bent trail leg at the chord results from the athlete trying to pull their legs up, rather than swinging around the top hand.
Agreed.
tsorenson wrote: This premature pull with the top hand also results in loss of pole speed/penetration. ...
I don't think you meant to say this. You were talking about the bent trail leg ... then morphed into "
premature pull with the top hand".
While I agree with your quote, it seems out of context.
Let me get back to typical flaw patterns that I've observed ...
1. When just beginning (< 3.00m), the vaulter's intent is to "get upside down" ... and he'll figure out how to do that any which way he can. Often, it's by tucking the trail leg at the wrong time, and by pulling with both arms at the wrong time. I think the reason they pull with their arms is becuz they lack the strength to invert "properly" ... and they haven't been taught "properly" - yet.
Getting back to JRogers' bro, it's unusual that he would attempt to tuck the trail when passing the chord. By 15-5, most of that inappropriate tucking should be already gone (but maybe not). However, I suspect it might be a remnant of his beginner's habits. He's intermediate now, but probably hasn't done enough highbar or ring drills to shake that habit. So your advice re this is dead on, Tom.
tsorenson wrote: ... The best drill for this is just swinging back and forth and trying to stay long and get your forward swing up as high as you can, almost to the extent of whipping all the way around into a "giant swing". Once you do it right about 1000 times on the apparatus, it should become second nature on the runway ...
I would emphasize the downswing more than the upswing. If the downswing is done properly, there's not much to the upswing ... you can more-or-less just coast to a stallout.
Re giants ... again, it's the downswing part of them that's important - up to and including the whip (when you pass under the bar).
Lest anyone gets the brainwave that they should do giants with the lead knee up, I don't recommend that. The only exception I'd make to that is if you ALREADY do 2-legged giants perfectly.
Rationale: Giants are hard enough on their own, without adding difficulty to the trick by keeping the lead knee up. It's the FEEL of the giants (especially thru the whip) that you want to drill into your muscle memory ... not the precise simulation of the vaulting action.
However, simple swinging drills UNDER the bar should be with lead knee up ... to simulate the vault more closely. Also to improve your strength to be able to hold the lead knee up.
Kirk