if you've got some cash to spend, swap out your cassette and rear derailleur for mtb ones. entry level shimano or sram components would set you back maybe $40. your highest gear should stay about the same (53x11) while your lowest would be a lot lower (39x32) than with a standard road cassette. for long climbs i get on the tops and spin about 80-90 rpm.... i've found it's better than mashing a big gear up the hill