In my learning to stand-climb, for me at least, cadence is critical; High cadence, geared too low, low stress on handlebars (critical for my ultra-long folder handlepost) but run out of steam quick; Geared too high, cadence too slow, and I need to yank hard on the bars, and also tire quickly from high muscle forces; I found the key is to use the highest gear where I am able to climb, mostly with just my weight on the pedal for each stroke, the handlebars just stabilizing the bike laterally, without hard pulling. This is very efficient, as leg forces are closer to walking, and lower stress on the bike. Bar-ends, tilted up about 30 degrees, with 45 degree bent ends at the front, I grab there when climbing, hands are higher, and it moves my torso forward to position my hips (with a straighter leg when standing) over the "front" pedal when at its forward (horizontal crank arm) position, so all the force goes down, not any forward, if my hips were further back. Road racers do the same by grabbing the brake hoods (which I never did on my old racer, I hated drop bars, I set mine up for bullhorn bars). I figured it out myself (the cadence part, grabbing the bar more forward is known), I don't know if this is recommended technique somewhere authoritative.