I've only averaged up to 16 mph on my commute from Lenonia to Manhattan (park and ride) or from Bloomfield to Manhattan (from home). There's just way too many lights and cars on my route. So 20 mph avg is a tall ask. There's also a decent hill (9% grade) from Leonia to Ft Lee that forces me to shift into a 39x26 and sometimes wish I had a 27 or 28 when I'm tired. So you ain't going to be fast on hills like that, either. About the only place that I could even pedal top gear (53x13) is on a downhill in Teaneck. But even then, there's a light a little after the bottom of that hill that I have to watch for. Probably the only real way to get 20+ mph avg might be at 2 or 3 am and blowing through red lights...