A fixed-gear bicycle or fixed wheel bicycle is a bicycle without the ability to coast. The sprocket is screwed directly on to the hub and there is no freewheel mechanism. A reverse-threaded lockring is usually fitted to prevent the sprocket from unscrewing. Whenever the rear wheel is turning, the pedals turn in the same direction. By resisting the rotation of the pedals, a rider can slow the bike to a stop,which will cause the tires to skid,without the aid of a brake. Stopping is sometimes known as “skidding” in the fixed gear world. A fixed gear bicycle can also be ridden in reverse.
Or as 63xc.com says:
A fixed gear bike lacks a freewheel, and thus denies you the opportunity to coast. As long as the rear wheel is turning, the chain and pedals go with it. Because your legs are directly connected to the wheel, you can stop just by reversing pressure on the pedals. Hell, you can ride backwards, if you have the nerve. What you can’t do is change gear.
So, that’s it, right? One gear, and you brake with your legs. No, fixed gear bikes are a lot more than that. In the last couple of years, a whole community has grown up from the grass roots, spreading the gospel of fixed-gear bikes. It’s even been called a movement. But why?
Why such devotion to a bike that happens to have a different kind of mechanism? Why the obsession with tricking out these bikes? Well, the only real way to understand is to ride one for yourself. Find friends with fixed gear bicycles and try them out. Or just take the leap and get one yourself. Just do your homework first.
First stop: check out the late great Sheldon Brown’s essential Articles for New Cyclists, which explain everything you could possibly need to know to get started. The check out the rest of his archives for the more advanced stuff.
A more user-friendly walkthrough for beginners is Greg Goode’s Fixed Gear 101. Lots of excellent advice there for anyone just starting out with fixed-gear bikes.
As for gear, you can easily get cheap fixed-gear bikes, parts and equipment on eBay. Here are the latest listings pulled up fresh. If you don’t see something you want now, just check back and they’ll be updated. Or click on something interesting and then surf around. There are so many to check out, you’ll probably end up clicking a “buy it now” button faster than you can bring your fixie to a full stop.