Sidney "The Blackadder" Poitier was a formidable presence in early 70s British motocross.
A mountain of a man, he was hampered in part by the fragility of the machinery.
BSA supposedly developed the B50MX in part to cope with Poitiers relentless riding style.
Gear box problems plagued the early bikes, the shifter quadrant on Poitiers bike gave up the ghost with half a lap to go at one event, locking up the gearbox.
Sidney simply picked up the bike and dragged/carried it to the finish line, no small feat in 2 feet of soggy northern mud...
Pic is from the movie "A warm December".