[look 171]

Originally Posted by greglepore

In an urban environment they are a hoot, the instant acceleration/deceleration is an advantage in traffic, as is the increased ability to trackstand (the ability to apply reverse torque to the rear wheel makes it much easier).

You mean to tell me you can't accelerate and decelerate faster in a normal road bike then your track bike? Keep in mind that I am always in the right gear on my road bike. If you are a good rider, you can do a track stand on a road bike all day long in traffic. I have done many 50 miles rides in LA traffic without undoing my straps taking my foot out. This was before clipless. I even have the Cinelli death trap pedals. edit: Still got em'.

Allegedly they will improve your spin. Using legs for brakes definitely works muscles that don't get worked during normal riding, but I don't know whether this qualifies as "good for you".

Why do you need a fix gear to help you with spin? As a (good) bike rider, you should have the discipline to keep the pedals spinning smoothly at a certain RPM without the aide of having the pedal push your legs, or a computer telling you your cadence. A good rider is smooth and discipline. Work your other muscles? Most of the time, you are just standing on the pedals to slow you down. The only muscles that are important are the muscles that help you go forward, not backward.