Doubt the following applies to most here, except maybe a few of the brakeless detractors I've seen.
For starters, I dislike the phrase Fixie ( I only started hearing this used a couple years ago). Maybe I'm wrong, but it's always implied to me taking a beater (Schwinn LeTour for example, no offense) and slapping some road cranks less a ring and a 3/32 cog w/ a lockring on and away you go. That's a no-no in my book. Frame geometry alone is an issue to be aware of, not to mention higher end materials and craftsmanship used in cranks, drops, stay tubes, etc.
I've snapped several Suntour Superbe cranks in half over the last 22 years, so I doubt the rigged up stuff is gonna cut it.
If the bike has a hanger on the rear, don't bother, given you can get a complete off topic track frame (Pake, Leader, etc) and generic wheels and cranks for less than $350. Get a feel for it and decide if it's something you can dedicate yourself to learning. Let's face it, it's not for most folks.
In my opinion, riding a track bike in traffic is something you need to take seriously to say the least. Many do's and don'ts.
You must be willing to understand and accept your initial limitations and learn from them before you become proficient at this style of riding. It's an art of sorts. The bike is an extension of your body. You're in your bike rather than on it. Nice, huh?
Every once in a while I'm asked politely how the bike works without brakes. I can explain in less than 60 seconds and the individual usually comes away thinking it's hard, but not that it's dangerous. It's neither of course!
My gear of choice is 49x16. I've tried lesser and quickly went back.
As for brakes, well all I can say is if you feel the need for them, then you probably shouldn't be riding fixed. I've seen firsthand and heard numerous stories of guys flying over the handlebars using them.
Then again I'm sure there is a place for brakes in certain circumstances, but I can't think of one that applies to me. Let me know! You ride on the sidewalk only maybe?
I've worked as a messenger for 25 years and own and operate a service for the last 15. I can count on 2 hands how many days I didn't ride my fixed in the last 22 years. No knee problems yet and don't think any will come soon as a result of riding fixed.
I started with something cheap (not really - it was an Alpine frame, but with cheap Suzue hubs, etc.) and finally have worked up to a nice collection of 6 track bikes. No reason nobody else can do this too.
I certainly don't encourage bar crawlers or weekend riders (the fad factor in question) to be taking their fixed out for the night as I've noticed. Too much posing and alcohol! Take it seriously before you get hurt or hurt someone else. Again, this certainly is not addressed to anyone on this list of course.
As for those younger folks inventive enough to rig up something solid to ride for the learning process, Bravo! Just don't make a decision about continuing without trying as close to the real deal as possible. True Track Bike! There's plenty left for ya.
Let's just hope the new fad isn't brakeless freewheel. Uh oh!
Kevin McCaul
Trackstand LLC
Silver Spring MD USA
Sorry for the self-promotion, but I'm proud of the name.