Thanks for your answer, which very much surprised me. I was expecting you to say use a fast shutter speed due to the speed involved.
I shoot motocross and my biggest challenge is getting the rider sharp as he comes over a jump.
This is a 'blind' setup really as you cannot see the bikes until they have started to take off and then the autofocus has to kick in, then VR and then shoot........many come out very soft or blurred, and thats of shutter speeds at 1/1000 sec!! I mostly shoot around F5 unless i'm using the 24-70 F2.8 to get closer, and i shoot continuous and single focus point .....
So i must be doing something wrong, in which case i shall give your suggestion a go Chris and see if it works for me
Thanks for the other comments gents, informative
It won't be till after Xmas when i go to the track again, see how i get on...
Cheers
Martin