I just started commuting about a month ago. When I started I was doing about 55 minutes per 10 miles, now I've got it down to about 38 minutes. I hope that I'm not doing anything wrong, but I just make sure that I'm always peddling and I try to never get off my seat. I also have a few strait aways that are at a slight upgrade that I really push myself to be faster at. In a month I can see a major difference, especially when I'm riding with someone else and I'm able to rocket up an incline leaving my partner in the dust... Also, something noticeable is when I eat a Luna bar about 30 minutes before I start my ride. That seems to help a bunch!