I tore up my shins so badly on my own pedals while practicing hops that my wife said I couldn't ride until I did something. I got some cheap stuff from REI and as expected, their large was too small. I am 6'6" and 230. These L/XL fit perfectly and ride well. I don't like wearing gear, but they are now like a helmet to me: I won't ride trails without them. I have yet to have an accident where the hat mattered, but the shin guards have saved my hide again and again. If this stuff wears out before I do, I will buy another immediately.
The guards do their job without calling attention to themselves. I am 6'6'' 230, and used to things not fitting. The L/XL slipped on like the glass slipper going on Cinderella's foot. And no fiddling with straps or fittings.... They just slide on and I smooth down one velcro strip and go.