tomatkins wrote:I don't think that bending over to put pressure on the "down-stroke" is bad for the lower back... but bending over and pulling up against the resistance of the pump on the "up-stroke" is what may be straining the back.
Therefore, it might solve all your back issues if you simply unscrew the top of the pump and peal off the little round rubber flap of the "up-stroke" valve... and by doing this, you will disable the up-stroke pressure and only compress air on the down-stroke.
Since you will then work the pump "faster", the overall time it takes to pump up a kite will not be much longer and your back will thank you.
This works, did it a while back. It's the pulling up that is putting strain on back, especially when the seals dry up,a bit. But yea, a straight back is best. I also ditched the small Slingshot pump and went back to an old, but taller north pump.