As FB pointed out, suspension is hardly needed on a road bike. Most of the time the suspension mechanism is gonna be robbing you of the speed and/or momentum that you need for efficient propulsion. I remember buying a mountain bike when suspension (rear and front) was relatively new. I intended to ride the mountain bike mostly on paved river trails. I really wanted the bike with the rear suspension, but could only afford the hardtail (Cannondale Delta V and the Killer V 900), but today I thank my lucky stars I opted for the Killer V 900, as it is a much more versatile bike for all the right reasons.