There was such a thread many moons ago, but instead of pulling up a year(s) old thread, I thought I'd start a new one. I found some pics on SRAM's CX blog that pretty much define "dirty bike". I'm guessing from the photos that the CX race was done under slightly moist conditions:
That is one dirty bike!! I would imagine there was some tuff pedaling through that muck.
Knowing the crowd here, however, I suspect that some of your 'dirty' bike pictures might involve more than just mud.... So I'll forsake this thread lest I be embarrassed, lol. [IMG]/img/vbsmilies/smilies/biggrin.gif[/IMG]