. The 38-11 high gear combination you will have doesn't sound very fast, but in practice it will be fast enough..
It might be "fast enough" but it will be very frustrating on a long flat road.
I often "slow pedal" for the majority of the day out on the great plains.
If the wind is behind you or it is a slight down hill you will find yourself spinning out rather frequently instead of a steady cadence.
Furthermore, I like to stand on the pedals on a long flat road once in awhile to use different muscle groups or to take the pressure off you butt. You will really spin out fast with a 38/11 gear combination.
A mountain triple will solve this annoyance. (44/11)