This is a tough question since there could be many reasons for this, but I would like some feedback:
I have pain in my right leg on the bike. It sometimes feels like it’s my vastus medialis tendon, sometimes in the belly of my quad, sometimes IT band, sometimes hip flexor. Basically everywhere and nowhere at the same time. It is bad to the point where I have not ridden in 2 weeks. Got back on the bike yesterday, same pain right away.
However, I can run (long runs, track workouts, everything) with no pain at all. I try to initate or recreate the pain by doing lunges, walking lunges, squats, stairs, anything: no pain.
Yesterday I did a very successful track workout, finished with some plyometrics, etc. Zero pain. I thought, “well if I get on my bike there is no way my leg can hurt today”, sure enough, immediate pain with the pedaling motion.
I get on the foam roller and use my tpmassage products to find any tight area or pain: nothing out of the ordinary at all. I can swim, no pain in leg. Standing up and pedaling on the bike: no pain. As soon as I sit in the seat and initiate the pedaling movement, bad bad pain.
My right side of my back hurts a little lower side. Could I be compressing a nerve when sitting on the bike? Anyone had anything like this before?? Could my right knee be slightly out of joint?
I just read an article about it happening when people craned their necks in the aero position and had arm pain but the source was cervical spine problems. The interesting note is that these people could swim and lift without pain.
This sounds similar to your problem but in the leg. Maybe some sort of sciatic problem??
You know what to do, get to a doctor.