I've been through 3 sprockets on my bike, trying to find a good cruising RPM for 30MPH. 44T maxed out at 32MPH (blowing the engine in the process), 39T maxed out at 38MPH, and I've never taken it over 38 with the 34T.
I was going 35MPH with traffic yesterday and a cop passed me with a thumbs up! I'll take it as a good omen