Originally Posted by
Carbonfiberboy
The old adage is "Pain in front of knee, raise saddle. Pain in back of knee, lower saddle." So the problem could have started because your saddle has been too low all along. Makes sense when one realizes that the greater the knee bend, the greater the down force on the kneecap. Thus spinning on the climbs or climbing standing are also good for the knees. One can also reduce force on the kneecap by smooth pedaling rather than hammering the downstroke.
Yes, I had my bike fit a few weeks back, realizing I had my saddle 1.5" too low! Years ago I'd had posterior knee pain, lowered my saddle then just got used to it. Then I stopped riding for a couple years, jumped back on without making any adjustments. Last weekend I hopped on my MTB, realizing of course my saddle was too low - like way too low. I raised it but still think I need to go further. That was the day after a pretty tough and hilly 40 on my gravel bike, so all the ingredients were there for a problem.