1.5 miles isn't enough time to get your legs warmed up. 5 miles barely is. I have two reasonable commute options. One is 8 - 9 miles, one is almost 14. The 14 mile commute has a few residential streets, then a 45-55 mph two lane with a nice shoulder the whole way. The 8-9 is 45-55 mph with no shoulder, blind curves, rolling hills. I take the 14 mile option.