Ground loss is Pi times radius, a relationship which doesn't change with the size of the circle (and it was interesting that Donaldson got this right in his book from the 30's, when so many have gotten it wrong since). This means that no matter how tight the turns a horse loses ground versus the horse inside him of Pi times a path (just over the width of a horse) for each turn, which as it happens is about the length of a horse.

I don't know the distances of the races you refer to, but here's a thought-- they move the rails out but still run an exact distance, meaning the turns are bigger, and the staightaways shorter (18 foot rail means about 56 feet more on each turns, that much less straightaway per turn to compensate). It's possible the run to the first turn is shortened enough to make it a little harder for outside horses to drop over and save ground before they get there.



TGJB