Pain in back of knee is often related to an overly high saddle. Constant overextending, particularly in cold weather or under high load, stresses that area no end.
Do your hips rock when you pedal? Do you pedal toes down? If yes, dropping your saddle 5-10mm would be a good place to start.
I try to dip my heel at the bottom of each rotation, so it sounds like I could be over extending and then putting pressure on it,
I'll try and keep my foot flatter and lower my saddle a touch
I try to dip my heel at the bottom of each rotation, so it sounds like I could be over extending and then putting pressure on it,
I'll try and keep my foot flatter and lower my saddle a touch