tony cooper writes:

I've never seen - let alone photographed - a roller derby, but I've
photographed greyhound races. I always shoot from a beginning of the
straight-away as the dogs come around the fourth curve. There's
action as the dogs come out of the curve, and I can pan on the action
at the beginning of the homestretch.

That sounds like about the same idea, yes.
--
Googleproofaddress(account:dd-b provider:dd-b domain:net)
Snapshots: http://dd-b.net/dd-b/SnapshotAlbum/data/
Photos: http://dd-b.net/photography/gallery/
Dragaera: http://dragaera.info