Knee pain

I've suffered from this problem myself, on the right side. My left leg is slightly shorter than the right. when I was younger this was not a problem, but older and less flexible, it has become one. It wasn't noticeable until I'd start to hit higher mileages, then my right knee would give out. The pain was actually on the outside of my hamstring right by the knee, and would spread down to the right side of my upper calf if I persisted. my body would lean ever so slightly to the left to compensate for the leg length difference, with my right knee brushing the top-tube, this putting a little extra stretch into the outside of my right leg.

I've fitted a home made plate to my left shoe. I did this myself, after some reading, without a pro fitting, adding just a couple of mil. Theres a fair bit of difference in leg length, but advice in these cases is to add a bare minimum, and I assume the reason for this is that your skeletal/muscular system has already adapted over a lifetime to cope with this difference. It has helped.

also, I've fitted Speedplay frog pedals, which are freefloating. Another symptom of my odd leg length was that my right heel had a mind of its own, wanting to sit where ever, depending on its mood and the terrain. This would put extra strain on my knee as my heel would be straining and fighting against the float limit. The combination of the plate and the frogs have helped my heel to align more easily.

Also, I'm now wearing Specialized shoes, which have a slight tilt in them, this may or may not help, but they do have a slightly exaggerated arch section which has alleviated the cramps I get in my foot arch.

Unrelated to the same problem probably, but I'm also using shorter cranks now on my main bike to reduce the work my knee does. As you can see, the persistance of my problem made me make some major changes.

Might or might not be your problem, but worth considering if riding road means youre now doing extra miles, which would exacerbate a possibly otherwise un-noted situation