Your bike may look like a simple machine, but it's actually a marvel of engineering that took over a century to develop. In particular, the transmission allows you to pedal naturally through a range of speeds, shifting gears to suit your power needs and making it up hills. This elegant transmission is the key to a freewheel bicycle, the standard for bikes in the 20th and early 21st centuries.
A freewheel is a mechanism incorporated into a bicycle transmission. The freewheel is controlled partially by a ratchet, which has angled teeth that only allow it to turn in one direction. The ratchet is attached to a sprocket or wheel with teeth, which interlocks with the bicycle chain. The effect of a freewheel is to allow the rider to pedal when moving forward, then stop pedaling while coasting. Without a freewheel, the rider would have to pedal whenever the bike was moving because the pedals themselves would always be in motion.
Bicycles have been around since the early 1800s, but the bicycle transmission has undergone continual development. According to cycling historian William Hudson, the first freewheel patent was obtained in 1869 and the first commercial freewheel bikes became popular in the 1890s. In the first half of the 20th century, the freewheel bicycle industry was dominated by European manufacturers. However, in the mid-1970s, Japanese companies began to release new, superior designs at a lower price. Bicycle expert Sheldon Brown says Japanese freewheels had better-shaped sprocket teeth and stronger notches, making them more reliable.
Freewheel vs. Freehub
While most modern bicycles are freewheel designs, the freewheel itself is increasingly incorporated into the hub, a design referred to as a freehub. According to Bike Pro, this is because conventional freewheels must have a minimum of 12 teeth. To have more control over the bike gears' effectiveness, it was necessary to change the design. Freehubs are threaded rear hubs, with a set of sprockets that slide onto the hub itself. This has the added benefit of reducing a bike's weight and improving load distribution and rear axle support.
Freewheel vs. Fixed-Gear Bikes
Fixed-gear bikes, also referred to as fixies, gained popularity in the early 2000s. They are often used in urban cycling. A fixie has no freewheel, meaning the pedals are always in motion when the bike is moving. Fixies may also forgo brakes. Riders use their leg muscles to push back against the pedals and slow the bike. Fixies have only one gear, as opposed to freewheel bicycles, which may have between three and 21 speeds. Freewheel bikes are considered the standard for cycling, whereas fixies are simpler to maintain and often more affordable.
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