For taking anything that's moving using a tripod especially for motorposrt peronsally speaking is pointless, you you can't get a steady shot of something moving fast with whatever lens in the 200mm range with a shutter speed of 1/250 or above then you must have shaky hands.
Personally, I wouldn't use a tripod either, except for a particular situation, like if I wanted a tightly framed shot where there's a lot of crud just out of the frame.
The sportsshooters use monopods 'cause those heavy 400-500mm fast lenses weigh a ton on the end of the cam & they can't afford to lose a shot while they're picking up a cam hanging from their neck.
Afterthought to what I said in post #54 & the pic in #43:
That pic pretty much negates what I said. Notice I was standing just inside the curve with a wide angle? But I was much younger then, & indestructible! 
L!
