I'm about 210lbs and 5'10" so not TdF material. I ride a hundred miles a week, but it's those hills
that just kill me. I did a century last year with 2500' and it kicked my butt. It was a big reality check for me as most folks consider that to be a flat century. I imagine the only way to get better is to ride more hills and loose some weight, but some stories of "big guys" who started out hating hills, but got to love them, would be encouraging.