Yesterday I went for a 27 mile ride which had some moderate hills (Ive done 30 mile rides previously that were mostly flat) and on my return trip my right knee started hurting with every downstroke and it got worse. Stopping to rest didnt seem to help at all, also had plenty of water/snacks. By the time I got home my knee was swollen, stiff, and hard to bend. When I did bend it I would get a sharp pain on the lateral (outside) side of my knee. Im not sure exactly whats wrong (IT band, ligament strain?) but I want to make sure this doesnt happen again.
When I got the Trek FX they fitted me at the store and it feels good but I see many online charts Bike Fit Calculator | Find Your Bike Size | Competitive Cyclist for example) that say my seat should be higher. I do feel that it could go up slightly if needed but that site recommends 41" seat height (ground level to seat, I added the ground to BB measurement) and mine is currently at 37". Could this be the cause of pain or perhaps improper form?