I built my bike a couple of years ago after selling my old Cannondale road bike. It was a good bike but was a bit big for me and holds bad memories for me as the last time I rode it, I was almost run over and the bike was.
I had stopped on the way home from work to fix a puncture when some rude boy in his Rover (my Grandpa had a Rover!) lost control on a bend and ran the bike over. I had by this point dived into the safety of a bush but the mental scars were there so the bike had to go.
I chose to build a single speed simply because it was simpler to do (no gears, shifter and derailleurs to complicate the job) and it would hopefully get me mega fit!
I chose a frame from On One, a small firm up in Doncaster who specialize in steel single speed delights and then got the other parts from various other sources. Alpina carbon fork, Miche chainset and hubs, Mavic rims... the list goes on. Anyhow, the result was a beautifully light and comfortable bike that is unique. Single speed bikes are quite rare in the Chilterns for some reason!
So now comes the sad job of weighing it down with a luggage rack and an extra bottle cage. I will also be adding some comfier bar tape before long. The blue track grips match the tyres nicely but they don't damp out much vibration!