Howard Darr wrote asking about feasibility of getting fixed at the young age of 43.
I didn't start riding fixed-gear until 52, and haven't coasted at all for the past 3+ years. It's fun & can be adictive. There are quite a few fixed-gear riders (besides numerous bike messengers) in the DC area.
Probably the most important thing to keep in mind when starting out is to choose where you want to ride until you get comfortable with it. Flat is easy, rolling hills are fun also, but long & steep can be difficult. Typical gearing is 42x16 or 42x17 with 700c wheels (65-70 gear inches) - but there are those who go far outside of this gearing. On the track it's closer to 90 gear inches. We have some regular fixed-gear rides in our bike club and try to pick fixed-gear friendly routes - but even then some of the terrain can be challenging - especially for someone just starting out.
If converting a road bike, you should be ok if it has the classic Campy semi-horizontal dropouts - that makes it a lot easier to adjust chain tension. Many older bikes also have higher bottom brackets than are currently popular, so there is less chance of striking a pedal when turning since you can't coast thro the turns. That's generally not that much of a problem, but I like using 165mm cranks, plus I feel that I can spin better with them.
As far as stopping - use a brake. I tried it without a brake for a bit since I didn't want to drill the fork of my '73 Eisentraut track bike, and can do it in flat terrain, but not in the hills. Plus I was dangerous without the ability to stop quickly. I ended up installing a road fork on the Eisentraut, so can still convert it back to original condition.
Non-confidentiality Notice follows:
The information in this message is not confidential and if it was I would not be stupid enough to send it via unencrypted email. No lawyers were involved in the composition of this email or this notice and no electrons were harmed in the transmission of this document. If you have received this message in error, big deal, just hit the delete key.
Ben Sanford
Falls Church, VA