Flat horse racing is when a horse is racing on a flat. a flat is a course without jumps. Flat horse racing is horse racing without jumps.
A bicycle
That will depend entirely on what type of racing you intend to be doing.
It is used for bicycle racing.
Velodrome
One A Season of Bicycle Racing - 2007 was released on: USA: 14 April 2007 (DVD premiere)
yes maybe
Sailboat racing
Flat racing is not a recognized form of racing
There's harness racing and flat out racing.... Flat out racing is most common in thoroughbreds, appaloosa's and quarter horses. Harness racing is saddlebreds.
bicycle racing
These days - usually not.