I’ve suffered similar problems throughout the summer, mine turned out to stretching off after a ride, something I’ve never ever done. Throughout winter I get back, shout the good lady wife to bob the kettle on and seek shelter inside the house asap. As spring and Summer arrived I was less eager to go indoors and as I cooled off a bit I started stretching out
I’ve acquired a few riding pals over the past 12 – 18 months and as a result I’ve picked up a few of their habits, stretching off being one of these, ordinarily I’d slow it down before I stopped, do a few loops in the car park or in the road or ride around the housing estate to loosen off. A fortnights holiday and it was gone, I stretched off and low and behold it came back. I’ve gone back to not stretching now just in time for the inclemant weather. Knee is all good.
I had a bike fit recently too, my saddle was lowered 3cm stem shortened 3cm, I was advised to narrow my bars 2cm and shorten lengthen my crank arms 2.5mm. I merely suggested if I didn’t lower my seat I wouldn’t need to extend my crank arms? I’m sure there’s more to it than that but low saddle short stem narrow bars sounded wrong,