My longest commute was only 28 miles each way (56 total) and I was on the road for 2 hours each way. My route has plenty of hills. I am 50 years old and overweight and I can do it twice a week but it sucks. If the route is dead pan flat it doesn't matter if you have a multi geared bike but doing it on a balloon tire coaster brake bike is nutty IMHO. I half drive and only bicycle 17 miles round trip three times weekly and my route is flat. It takes me between 27 and 40 minutes each way depending on how hard I want to ride. Multiply my times by 3.5x to 4x for a realistic ride time. I ride a 65 inch gear but my bike is a 21 pound 80's conversion single speed with 1-1/4 inch 95 psi tires. Your balloon bike will be harder to pedal. Too bad you couldn't ride a fared recumbent. For a flat route that would be much faster.