I'm not so sure weight is the main issue here. I started riding mtns at 260. One bud said I could never beat him as he had the marathon body at 145 (5'8). That's one you don't do is tell me I can't!
I've always been active and athletic so I started riding hills 3 times a week knowing I could get in shape. I ate sensibly, rode hard and before I knew it, I was 220 lbs. I still outweighed him by 80 pounds, but I drilled him to the ground on the next mtn ride we did together. Needless to say, he won't ride with me anymore!
I started doing 40 mile rides with 5,000 ft of climbing, most in the first 21. I did midweek rides which included 2,000ft within 10 miles. It was all getting used to the climbing, getting comfy and finding a groove. I kept traing then did a timed even. A century with 10,000 ft of climbing. I placed at #123 out of 400. The registration said ,"don't register if you aren't a serious climber/rider", but I did!
I ended up doing that ride 3 years in a row. I didn't rain much last year but still did a 114 mile ride with 12,000ft of climbing. I used a standard double 39/25. Not as fast but still completed the ride at 235 lbs.
I don't think it's as much about weight as it is training! (I'm 6'1). The more you train, the better you climb!
Plus, I know plenty of skinny riders that can't climb cause they don't train!
No fancy lite wheels, no fancy gears! My climbing bike
Last year's ride