Thank you, everyone. I never even realized there would be PT bike fitters, and yes, we are close to Pittsburgh and only three hours from Columbus. Muirenn, my bike is a Cannondale Quick 4 with 3x9 Altus gearing that came with the bike. And I just realized that I said discomfort behind the knee instead of behind the kneecap. I have a bit of my own kneecap left and the discomfort is there. I'm afraid of getting into a bad habit of overpressuring the "good" (relative term) knee as the discomfort continues. I don't notice it until about 15 miles, and it lets up totally as soon as the pressure is completely off - downhill coast. At the risk of boring you all and overanalyzing, can I also say that, when I gear down and try to somewhat match my husband's cadence, I can't last and have to gear up. Is that a male/female anatomy thing? An artificial hip thing? A wimp thing? Yikes, so much to learn! Thank you for the encouragement and advice!