I'm 64 years old & my regular commute is precisely 4 miles from my garage to the door at work. Mostly flat but 1 big hill near work and a smaller one close to home. There is a possibility of 6 red lights, but I don't think it ever happens. Day in & day out my most common times are in the 16 to 18 minute range. My all time best was 12 minutes 30 seconds at 6:00-6:12 1/2 AM riding my fastest bike & no stops at any red lights. The longest commute time was 26 minutes & caused by a traffic accident which closed an intersection while they maneuvered emergency vehicles around the victims & their cars. If you haven't ridden much, you might get a little sore riding every day.