seems to just be age for me. I have been biking my whole life bit it was in my 30’s where when I do it especially a lot I would start to feel it. And yes I make sure my ride geometry does not allow for a deep knee bend. Anything really can set it off now and sometimes it just comes on its one. same with other aches and pains that have shown up over time. im not on the good side of 50 at this point though but it was in the thirties where the first things started showing up.