Having recently begun commuting Nth Sydney to Nth Ryde I find myself a) bored brainless and b) amazed at how many cyclists there are on the cycleway.
In an effort to relieve the tedium of the 13k ride I have devised a game to amuse myself - spot the MTBer doing training/undercover as a scummer. There are a number of attributes you can look at that give clues as to the likelihood, all unreliable, but anyhow.
With all this talk of Single Speeding, I thought I'd share my experience as a 'recent' convert.
I built up a bitsa for commuting, based on an MTB hardtail frame, some tired Crossmax wheels, hayes disks and odd bits I had around the shed. I got a rigid zion fork, for about $70 and that does fine for the road. No need for a lockout!