Ok so yesterday I under went my first long road ride of the year. A nice 64 mile metric centry, nothing hard mainly just farm roads. The first 30 we set a good pace where we averaged 23 MPH, and on the way home 17-19. But i noticed that the last 5-10 mile my left knee was starting to get real tired and sore. THis is unusual and I've never had this happen before. Granted this was only my second time on the road bike this year, but I've been Mt. biking pretty regularly and haven't had any troubles. I did a full century two years ago on this same road bike without any knee pain. Now the outside of my knee is very sore, it's ok to walk, but going up stairs hurts and going down is almost unbearable. It feels like it's on the outside of my knee joint. Any help would be great. thanks