I have been riding almost daily on my mountain bike, commuting to and from work (10mi/1way) and I'm able to maintain about 20+/-2mph on the flats (max speed of about 27-29mph down overpasses). If my current setup is: aluminum hardtail, Hutchinson Acrobat 1.35" (~34mm) slicks and Shimano pedals/shoes (M515); what should I expect to be able to do on the TCR?
Don't expect to go much faster if you already have narrow slicks on. Also, although I'm not "calling BS" on the speed you are claiming to maintain, let's just say that people tend to have funny ideas of what
maintain really means.
Anyway, I went through this a few years ago, switching from a mountain bike with semi-slick tires to a road bike for commuting and being the data collector that I am, I logged and graphed it. In the plot below you can see the speed jump in August 2005. Note that these are
average speeds. I would say that I was "maintaining" much higher speeds...
