Thanks for the nice comments folks,the best thing about this kind of event is bikes are circulating all day giving plenty of chances to change locations.They run in grid sized groups of roughly similar performance for 10 minute sessions with a short gap between.At mallory park the whole circuit is in a natural "bowl" with quite steep embankments very close to the track.This lets you change the shot completly just by walking back 20 feet.All my shots were taken from one of 3 locations-exit of 180 degree hairpin,exit from chicane and the start finish straight.
Exit from hairpin-bikes at slowest,cranked over and upright outaccellerating others.
Entrance to chicane-often bunched up lots of out braking going on.head on shots.
Tried using a tripod and prefocussing found bikes tend to move through POF too quickly!
Exit from chicane-overtaking,rear shot used the bank to get above them here.Panning essential!
Start/finish straight-high speed shots most of the scooters were above 80mph at this point-panning essential,shutter speed BELOW 1/125,also potential for atmosphere shots of lap boards marshalls etc.