Two years ago, as part of their mission to educate young women about breast cancer, thirtysomething ad execs Porter Gale and Donna Murphy set out on a four-month, 5,000-mile bicycle trek from Seattle to New York. While their journey is the subject of a documentary airing on the Lifetime cable channel this month, a bright, compassionate website (2 Chicks, 2 Bikes, 1 Cause) has been in place since the original ride. The medical links and health tips are beyond useful, and the on-the-road cyberdiary features both the joys of meeting breast-cancer survivors in 18 states and the ”joys” of cycling 120 miles a day. Heartwarming, informative — and you’ll just about feel the bugs in your teeth. B+