It is where the road looks flat but is actually a gradual climb.
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.
Flat racing is not a recognized form of racing
One A Season of Bicycle Racing - 2007 was released on: USA: 14 April 2007 (DVD premiere)
It is used for bicycle racing.
Velodrome
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.
yes maybe
bicycle racing
These days - usually not.
in hiking and bike racing