Originally Posted by JeffS
The word agility as applied to mountain and road riding has entirely different meanings. Until you can find an arugment not centered around a dirt analogy you've made no point.
If by road riding you mean the lycra clad adventure out of town I am about to embark on then agility doesn't really matter. The standards for measuring it are still the same though. If you want to talk about city or street riding whatever the term of the day is then not only should it have the same meaning as when mtbing but you run into the exact same problems albeit slightly less frequently.
-pedal strike while upright.(you aren't going to slam your pedal on a curb with a freewheel)
-the inability to corner as fast.
-a narrower range of speeds you can comfortably ride.
-IT IS HARD TO BUNNYHOP.(this is an essential skill that most fixed riders simply can barely pull off and hardly any are comfortable enough to use it as regularly as a freewheeled rider)
-poorer control over the pressure you apply to the rear wheel.(especially important in the wet)
etc.
Sure maybe you can live with these limitations but that does not change the fact that fg riding reduces agility in any meaningful sense of the word.