For those who wonder what fixed gear touring is like, I recently completed a 20 mile ride around New Jersey's Great Swamp on my FG bike. Certainly not an epic journey in terms of distance or hills, but long enough to give an impression of the sport.
The bike: In its present state, it's only two weeks old. I built it using an old frame and crank set plus new wheels. All bearings and races are either new or replaced, so the bike is mechanically "new." It has a 51T chain ring and 21T track cog, yielding about 64 gear-inches. The wheels are 700 x 23c with 110psi tires. It has only a front brake, which has proved more than adequate, even on a fairly steep descent.
The rider: I'm a 66 y.o. male, 5'10", 155 lbs., and ride about 20 miles per week, usually on a multi-geared bike. Since building the fixie, I've ridden it daily on a 4-mile commute. That has been my only FG experience until last Sunday.
The route and conditions: I carried nothing but a wallet, so I know nothing about loaded FG touring. The weather was spectacular - 70 degrees and sunny. The route may be familiar to some of you. It's a popular cycling venue described in several books about biking in NJ. I traveled the circuit counter-clockwise. The terrain is mostly flat with a few sections of rolling hills. The only steep stretch is a half-mile leading from Fairmount Avenue west along Southern Boulevard in Chatham Township. On this trip, I experienced it only as a descent. Some day I'll see if I can climb it without getting off the bike. (Climbing it on a multi-gear is tough for me but doable.)
Ride Impression: FG is definitely a little slower than geared, at least for me. Spinning isn't as fast on ascents, and you can't just let go and speed downhill. My average speed was 12-13 mph vs. 14-15 on a multi-gear, but I certainly wasn't trying for a "personal best." On flat terrain, the bike is as fast or faster than my geared bike, since the fixie is a bit lighter and has no drag from a derailler and pulleys. Most braking was with back-pressure on the pedals The only time I needed the front brake was the one serious downhill. (I do NOT advocate brakeless riding, even if you are a flat-lander!)
FG riding is very aerobic, but my knees/heart/lungs never felt over-taxed. Spinning on descents is actually relaxing and does allow you to recover from climbs. Some call it "pseudo-coasting."
Overall experience: Very pleasurable; I felt very unified with the bike. I've ridden a century and some half-centuries on geared bikes, and I would consider trying such rides on my fixie. I just wouldn't expect to finish as soon. I've never done loaded touring and don't know if I'd want to. I greatly admire those who do it - more so those who do it FG.
Recommendations: Get hold of a fixie and try it. Better yet, build one - it's not hard. My bike and I are still on our honeymoon, and maybe the novelty and enjoyment will wear off, but FG is way different from freewheeling. Everyone should at least experience it before making any assumptions pro or con.