Stiff locking ankles and knees when riding. Help!?

I used to get this as a teen, for a couple of years my knees in particular used to get very stiff. At their worst I couldn't cycle past the end of my driveway (about 200 yards!) without being in a lot of pain. It was growing issues for me, and I did grow out of it eventually - but there were things I did when I rode that made life a lot easier.

First off, I would really recommend you go down to the doctor and get it all checked out just to make sure you're all ok. Chances are it's either lack of fitness from not doing it, or something you'll grow out of but it's still best to be sure.

Then I would invest in a pair of sprenger flexi stirrups, the ones with the rubber on the sides, they are rather expensive and there are cheaper knock off versions if you can't afford the proper ones, but the official sprenger ones are the best. They really made a huge difference, they absorb a lot of the shock from riding - and take the strain off your joints.

I would also invest in some knee/ankle support wraps or sleeves, they really helped me a lot aswell - I also think they help stop your joints cooling down too quickly after riding. Same as horses, if you don't cool down properly you get stiff and sore.

Make sure you're warming up and cooling off properly before and after riding, it might not seem like strenuous exercise but you still use a lot of muscles and these need support and care.

Get it checked out however it's probably due to you not used to riding, or doing too much. No pain no gain!