“I’ll just quickly order some knee pads”, i thought. Immediate progress, I’ve found a size guide:

https://www.sixsixone.com/images/descriptions/2016-SixSixOne-Size-Guide.pdf

So i figured i just measure around my herculean legs (KFC’s finest), divide by two and pick the size that matches from the chart…. only no way in hell am I an XL. So, what bit of magic am I missing?

(unfortunately trying them on in a shop seems to be impossible).