1. Before figuring out what a race bike is, let's define what a race is. Road, MTB, endurance, tour divide. Raam, etc.
2. Now see which bike will give the rider a good chance of doing well in the race as specified in point one.
3. Different people will have different meanings for "doing well". Some will think coming first is all. Some will think a top 3 finish is what they desire. Others will think of finishing within a certain time. Etc.
Some weird examples:
If you have to enter a race where you're allowed to take the London Underground, then I'd be all up for a brompton rather than a drop bar road bike.
If half the race track is a mix of rough and smooth surface, I might want a cx bike.
Oh yeah, and the bike has to look cool.
