Road bike or mtb w/hp slicks, flat pavement, no wind, just cruising along at that certain speed where you're comfortably within your aerobic envelope/comfort zone - not dawdling, not hustling - just feeling good... the pace you could keep up for 3-4 hours...
You look at the speedo. What does it say? How old are you?
Variations of the same question are asked on in the golf newsgroup. Over there, almost everyone hits their driver 270+ yards.
