I love the internet. Or at least the information it contains that is accurate. And how do we know that?
I'm at least willing to take a shot at something, though. While checking my low checking account balance I took a look at "proper bicylce riding positions". And predictably, the internet came through.
What I found is that I have probably been overly extending my legs on the downstroke, resulting in a slight over-extension of my knees. The pain from this is usually manifested in the back of the knee...okay, the back of my left knee has been hurting for a week. So maybe I found the problem.
But as usual, there are questions. One, why did it seem to start hurting only around mile 9 of the half-marathon training run I did last Sunday, and then on the uphills in particular, and not on the stationary bike rides? Two, why doesn't it hurt while riding the stationary bike? And three, will stopping riding the stationary bike for a week or so make a difference?
I started the bike riding as a cross-training exercise last November when I was having some severe shin splint pain and was about to have to shut down my marathon training for a week or two. The bike seemed to stretch out the muscles on the inside of my shins, and the pain nearly went away. So I kept riding, logically.
Now I need to make a decision, and I suspect I'll stop riding for this coming week altogether, and on the off days try an elliptical or something and continue the upper body work. I'll also probably run on the greenbelts tomorrow for some distance, but not a half marathon!