This is a fun question to ask, but century courses can vary wildly in their difficulty. A century ride in Myrtle Beach, for example would be almost totally flat but the Assault on Mt Mitchell has over 10000 feet of vertical climbing. I'd bet a lot of people here could do a Myrtle Beach century at over 20mph in an organized paceline but only the verifiable studs can finish AoMM in 5 hours.

--Steve