Lately on my longer rides I've been feeling a very discomforting pain in what I can best describe as the "tendon" right behind my left knee. It only occurs when I'm sitting in my saddle and pushing hard. It feels sharper than simple muscle pain, almost like a cramp that lasts for half a second every time I push down with my left foot.

I've been reading, and some people have corrected this by lowering the saddle a bit. Does that sound right?

Is this something I should ice or stretch before riding? Am I warming up improperly?

I've done 55 miles before with no problems, but I just changed seats, which might have raised me up a little bit..I'm not quite sure though.

I'd also wager that the new saddle is a little higher. For me, adjusting saddle height gets to a point where I can't tell exactly what my knee angle is, but I can certainly feel it. Too low and the front of my knees feel stressed; too high and the back feels stretched like you're describing.

Can you tell if your hips are rocking more than before, too?