As long as there are no mountains or steep hills involved, my average fixed gear speeds (when riding solo) are identical to my road bike speeds. So you don't get extra time in my judgement. Lots of people have a mistaken belief that you can't ride a singlespeed bike as fast or as far as a road bike. That is mostly untrue, unless you start adding mountains or big groups of riders. 66 miles through NYC on a SS is cake.