I think my longest was about 11-12 miles and I recall doing that on my fixed gear road bike and it was uphill on the way back but there was subway on a good part of the route which I remember using once after getting puncture but I didn't ride as often as I wanted. These days my commute is about 7 miles and I do it on an e-bike to get there faster and usually after work I might get some groceries or might take some odd routes and explore a bit more or just get home faster. I can pedal average of maybe 13mph but with the e-bike I am closer to 18-20mph average. Beyond bad weather and extreme cold or having a very important meeting I generally am trying to commute via bike most of the time. It is quite nice and I really enjoy it. Plus not being a morning person I can get out on the bike without excuses. With my regular bikes which I still ride I wouldn't want to commute as much for one reason or another now I don't use those excuses my brain is able to eliminate them because I don't have to be as awake and ready.