agreed, but even on the flats, the highest gearin on a roadie is usually around 44-13, thats 91 gear inches (was the raleigh afore i 'fixed' it). The avg fix runs about 65-75 gear inches. At full cadence on a flat, 91 gear inches will make you go hella fast.

depending of course on the specific bikes involved. id say at best a fixed vs a roadie on pure flats can keep up. and yeah, the roadie takes changing conditions way more energy effeciently. specially for a long ride. theres a lot to be said for keeping optimal cadence for a few hours, versus bouts of sprinting and resisting (hilly ride) for a few hours..