Originally Posted by KingTermite
Yes....time trials have them on a trainer or something so their momentum is already built up before they're let go.
WTF?
They're still starting from a dead stop, usually from a slightly raised platform with a downward sloping ramp. You see the riders on a trainer before they race, warming up the muscles so that they don't have to waste the first few miles getting their muscles working properly - every second and every mile counts when you're racing against the clock.