Is it possible that:- you're trying too hard? I mean like pushing to go faster rather than keeping a steady, comfortable cadence (I gauge by my heart rate and breathing to see if I'm trying to keep an unsustainable pace)
- you're entering the climb in too high a gear and burning all your energy early in the climb? (this was my chronic problem...plus I tended to be unable to shift in the climb because of the added torque on the gearing)
I suspect it's a combination of training and technique...but hey, worse case, there's no hill that can't be walked!
If you don't grow where you're planted, you'll never BLOOM - Will Rogers