Introductions - Hurst behind the knees!

I feel pain in the exact same spot in both legs after approx. 15 miles of road cycling or 3 miles of jogging, without fail. I can do more than 15 miles of riding through the mtb trails w/ no pain. I guess it's the repetitiveness of riding on the road (or jogging) that leads to the pain. I've looked at diagrams of the leg and the pain seems to be where the biceps femoris connects to the head of the fibula. Basically, the spot behind the knees on the outer-sides where that long ligament ends just below the knees. It's pretty easy to see and feel. This is horribly depressing since I have to stop and get off the bike (or stop jogging) when I have so much energy left in me. I'm only 38yrs old. I've gone on 2-3 rides a week, each about 6 to 15 miles for about 2 years now. Does this sound like weak muscles being overused or possibly something else? If this is familiar sounding to anyone, any suggestions on how to address this issue??
Thanks all!!
Jimmy

The general rule of thumb is: pain behind the knee is seat too high. Pain in front of the knee means seat too low.
I recommend dropping the seat a little. Maybe a thumb width.

Look up 'miniscus'. It's cartilege between the bones. Different activities stress it in opposite places. I'd adjust the seat as above, maybe even raise the handlebars. At 67 I'm not allowed to play tennis or run, but I just biked all the way across the country without even a twinge. If it really bothers you, get your doc to prescribe an 'anti-inflammatory'. That saved the day for me.

Wow, my spelling could use some work. That's what I get for posting at 3am.

Thanks Scrockern8r. I'll give it a try.

Thank you dayjack119!