https://www.bikeforums.net/commuting/

when I do it, I use a road bike w/ drop bars. 22 miles each way. but when I was starting out, w. a 17 mile commute, one of my fastest commutes was on a MTB that was too small for me, w/ big flat slicks. something about the angles that had me hooked up good. maybe it wasn't the bike but a combination of other factors like health, weather, rest, fitness, motivation & nutrition? but I guess speed isn't the only measure of what works for someone. endurance & repeatability are probably important. meaning, can we do it, successfully & joyfully, over & over & over again. it's gotta feel right