Back of knee pain

I’m finally coming out the other side of a FAI (Hip impingment) & lower back problems that have plagued me since Feburary. I’m starting to get back onto the bike after alot of strength work and physio. I’ve had a bike fit, the bike fit instructor advised that he didn’t believe my shoes were right for my shape feet but said this would be the next step if I was still having issues.

I’m not having issues with my feet, but all of a sudden I am getting a pain the following day from cycling in the back of my knee. There is some discomfort on the bike towards the end of an hour. but the real pain is the following day. The muscle there feels tight and is noticeably agitated when I’m walking. The muscle is swollen in comparison to the other side. a straight leg and pointing my toes up feels like its stretching the area. Couple of days off the bike and it will go but will come back the day after training.

Could someone advise what that muscle would be? Its directly at the back of my knee in the middle, could possibly be my plantaris? Is there anything about a fit that could agitate it?

Could be one of these.

Also

Pain in front of knee = raise your saddle.

Pain in back of knee = lower your saddle.

Ensure at least that you stretch enough. I had a lot of problems with the legs and knees - nobody could help me - until I found out that the muscles were much too tight and I started stretching before each work out. Never had problems again.

gross oversimplification.

Could be myriad reasons. nerve, tight hamstrings, overuse, tendonitis, literally anything.

not everything is bikefit related.

Apparently you didn’t read their post all the way to the end: