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
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.
Velodrome
It is used for bicycle racing.
One A Season of Bicycle Racing - 2007 was released on: USA: 14 April 2007 (DVD premiere)
yes maybe
bicycle racing
It's a track for bicycle or motorcycle racing.
These days - usually not.