My averages for commuting on a fixie are down from my mtb! About 2-3 mph slower and 1-2 mins. longer to get to work, but oddly, I still get to work at the same time or a little earlier. I think it's the "never stop moving" I do on the fixie vs. "come to a complete stop" on the mtb. Oh well, I'll just have to get faster on the fixie!