The day I lost traction on my bike was a steep climb in my area only maybe 10%. I was standing trying to apply as much power as I felt the hill needed and apparently stood to far foreward and caused the back wheel to leave the ground. leaving the chain to keep rotating with no resistance, hence applying power against no resistance, foreward I go. Ooopps okay don't lean that far foreward while standing. Would have been good position for a flat sprint.

What I may be really asking is why in a max (full power) seated sprint up a hill the lifting happens? And why I litterally throw my body out of the saddle on the down stroke in a max (full power ) seated sprint?

Maybe I'm strange and you all apply max power differently. There have been times in the past in a full biggest gear sprint I feel like if I'm not careful I will seriously pull/tear ligiments and tendons so I back off. 15mph to 27 on a great day 30mph, feels like a very violent and potentially bad thing, not to mention very exhausting.