dear tout,
track bias is a result of a number of things, but mainly through uneven watering, and uneven use, of the racetracks.
The uneven use of the tracks comes about because the moveable rail is not used properly.
One week, for example, the moveable rail may be out 4 metres -- and the next week it is in the true position. This results in a 4-metre strip of turf on the inside rail which is "fresher" than the rest of the track when the rail is back in the true position.
The moveable rail should be used only for large moves, of say 10 metres, to ensure a large "fresh" strip which all horses can enjoy.
However, track bias is fast becoming the most exaggerated factor in horse race analysis.
As soon as a horse leads all the way, many claim there is a "leader bias".
If a horse swoops out wide to win, then all of a sudden we have a "swooper's bias".
Much of the time, it is nonsense.
A bias may be in play if ordinary horses are doing extraordinary things.
If the winning swoopers are 100-1 chances, then MAYBE their is a bias helping them.
But if odds-on chances are leading throughout and winning, then it is nonsense to put it down to a track bias.
After all, most of us expected the odds-on chances to win anyway.
Bias can play a huge part on days when the track is damp, or worse.
But on the vast majority of dry days, forget track bias.