How To Play The 5 Finger Run

I've noticed that I'm never able to pull off a 5 4 3 2 1 note sequence such as g f# e d c# with consistency at moderate to hi speed. so, what are some exercises to help with this? I've tried over holding, ultra articulated hand whips and wrist rotation but the prey remains elusive. I feel that the issues are not being able to flow an appropriate/consistent hand structure thru the whole arc of the movement creating uneven playing. it also seems that a mix of black and white notes doesn't help, as e.g. g f e d c is much easier. thanks in advance!

I would say the clues to the solution of your problem may lie in my third book, All Thumbs. There you'll find some new exercises to bring a sense of equality and rich relationship between the fingers which are by their nature, unequal in one way but equal in another... AFF