In my case, Elvis, my knee problems were just the first symptom that became really aggravated owing to general bad posture--but I actually have a long-standing hip problem, which apparently 'refers' stress to the knee. Because I'm astonishingly bad at locating specifically where pain occurs, I had never noticed this. I now do a (gentle) yoga course specifically for cyclists, which deals with all aspects of posture, and feel much better because of it. It may be that you sort out your problem with the kinds of specific interventions that the others mention, or it could be that a less localised approach to the problem(s) may be better for you. Good luck.
In my case, Elvis, my knee problems were just the first symptom that became really aggravated owing to general bad posture--but I actually have a long-standing hip problem, which apparently 'refers' stress to the knee. Because I'm astonishingly bad at locating specifically where pain occurs, I had never noticed this. I now do a (gentle) yoga course specifically for cyclists, which deals with all aspects of posture, and feel much better because of it. It may be that you sort out your problem with the kinds of specific interventions that the others mention, or it could be that a less localised approach to the problem(s) may be better for you. Good luck.