QUESTION: What’s the difference between a freewheel and a cassette, and which is better? —Ron S.
RBR’S STAN PURDUM REPLIES: “Freewheel” and “cassette” both refer to the cluster of gear rings — also called “cogs” or “sprockets” — attached to the hub of the drive side of a bicycle’s rear wheel. They both function the same in that they mesh with the chain to turn the rear wheel and thus propel the bike forward when you pedal. But freewheels and cassettes are different in design and construction. Cassette clusters are the newer technology, and most modern multi-gear bikes come with cassettes rather than freewheels.
That said, there’s nothing wrong with a freewheel if that’s what your bike is equipped with. The bicycle I rode across the United States back in 1995 had a freewheel with six cogs in the cluster. The bike I rode five years later on US Rt. 62 from Niagara Falls, New York, to El Paso, Texas, had a cassette with seven cogs in the cluster. Both bikes were loaded for self-supported touring and both did the job without a problem.
The big difference between freewheels and cassettes is where the ratcheting mechanism is located. That mechanism is what allows you to coast. The sprockets spin when you coast but lock and drive the bike when you resume pedaling. With freewheels, the ratcheting apparatus is built into the cluster, and the whole cluster attaches to the wheel by means of threads machined onto the hub. With cassettes, the ratcheting body is bolted internally onto the wheel hub — which to further confuse the uninitiated, is called a “freehub”— and you attach the cassette by sliding it over the splines on the freehub.
In terms of which is better, most bike mechanics would probably say cassettes are, and for two reasons: First, because freewheels screw on to the rear hub by means of machined threads, they leave a long section of the drive end of the axle sticking out unsupported (but not visible because it’s hidden by the freewheel). Cassettes avoid that problem. Second, freewheels can only be removed with a freewheel remover tool that matches the pattern of the particular freewheel, and there are several different patterns. For cassettes, there are only a couple of patterns so fewer lockring tools are needed to cover all cassettes (plus a chain whip, which is standard).
At one time, mechanics might have also said that changing individual cogs on a cassette is easier than on a freewheel, but the current trend in cassette design is away from personal customizing of the gear clusters. See more on that here.
The two systems are not interchangeable; to upgrade a bike from a freewheel to a cassette, you must get a new wheel (or, at least, a new hub).
Also, you are unlikely to find a freewheel with more than seven cogs in the cluster, so if you want more than that, you will have to switch to a cassette system. The bike I used for my Rt. 62 trip came with a seven-cog cluster, but it was a cassette, so when I later upgraded to nine-cog cluster, I was able to use the same wheel.
Stan Purdum has ridden several long-distance bike trips, including an across-America ride recounted in his book Roll Around Heaven All Day, and a trek on U.S. 62, from Niagara Falls, New York, to El Paso, Texas, the subject of his book Playing in Traffic. Stan, a freelance writer and editor, lives in Ohio. See more at www.StanPurdum.com.