Cassette hubs cannot accept freewheels; nor can freewheel hubs accept a cassette.
The freehub body of a cassette hub is shaped specifically for a cassette. Meanwhile, freewheels and freewheel hubs operate with a threaded system.
Thus, it’s impossible to mount a freewheel on a cassette hub. If you want to use a freewheel, you will have to replace the rear hub with a threaded one.
The Differences Between Freewheel and Cassette Hubs
- Ratcheting Mechanism
A freewheel hub does not come with a ratcheting mechanism on its own. Instead, the ratcheting mechanism is in the freewheel itself.
The purpose of the ratcheting mechanism is to “separate” the rear wheel from the freewheel when the rider isn’t pedaling. This allows the cyclist to coast.
In different, cassette hubs come with their own ratcheting mechanism. (You can learn how a cassette hub operates in this post.)
Subsequently, cassettes do not have a ratcheting mechanism on their own and represent a stack of immobile cogs.
- Attachment Mechanism
The freehub body of cassette hubs has a distinct spline pattern allowing the user to slide a cassette onto the hub.
The cassette is then tightened to the hub with a lockring.
In different, freewheel hubs have a threaded portion. The freewheel itself has threading on the inside and goes onto the hub like a nut.
Consequently, it’s impossible to install a freewheel on a cassette hub because cassette hubs are not threaded.
What To Do?
If you have a freewheel and a cassette hub, you have two options to come up with a working drivetrain:
a. New Hub
If you replace the existing cassette hub with a threaded one, you will able to install the freewheel.
That said, this procedure makes little sense for the following reasons:
- A replacement of the hub will require a new hub plus a re-lacing of the wheel. The final bill could be so high that it may be wiser to just get a new wheel altogether.
2. Freewheels and freewheel hubs are weaker than cassette hubs and cassettes. Hence why you will never see a freewheel on a quality mountain bike for example. By sticking with a freewheel system, the user is essentially downgrading their bike and limiting the options for future upgrades.
b. Get a cassette
The most logical choice is to buy a cassette that corresponds to the number of speeds that the hub can support. Cassettes under 10-speeds will be much cheaper than buying a new hub and re-lacing the wheel.
By staying with a cassette hub, you will have a more durable system and opportunities for future upgrades.
FAQ: Are there any benefits to sticking with a freewheel?
A freewheel does not have any notable advantages over a cassette. That said, sometimes it’s a good choice for beater bikes built on a very limited budget.
Another benefit of freewheels is that every time you replace them, you’re also replacing the ratcheting mechanism allowing you to coast.
Meanwhile, the ratcheting mechanism of cassette hubs is not always serviceable, and if it malfunctions, you may have to replace the entire hub.
That said, a quality cassette hub will likely last many years without a need for servicing if the bike is used for commuting.
How Can I Upgrade From a Freewheel To a Cassette Freehub
Method 1: Get a New Wheel and Cassette
The simplest way to switch from a freewheel to a cassette freehub is to get a new rear wheel with a freehub and an appropriate cassette.
You will have to make sure that the wheel can fit within the dropouts of the bike. To do that, measure the O.L.D. of the current hub.
The term O.L.D. refers to the usable part of the hub between the two locknuts.
If you have an old bike, the dropouts may be too narrow for a modern cassette hub.
If the bike is made of steel, the dropouts can be spread to accommodate a cassette hub of wider O.L.D. If the frame is made of any other material, this procedure should not be done for safety reasons.
Method 2: Replace The Current Hub
The other option is to use the existing rim and lace it on a new cassette hub. You will also have to buy new spokes because the old ones may be too long or too short for the new hub.
This procedure is obviously not beginner-friendly because it requires the ability to do the following:
- Remove the tire from wheel
- Remove the spokes from the rim
- Re-lace the rim around the new hub
- True the wheel and get the spokes to the necessary tension
- Re-mount the tire
The hardest bit is, of course, the re-lacing of the wheel. If you’re new to the sport, and you don’t have the desire to learn complex repair skills requiring advanced tools (e.g., a truing stand), you’re better off paying someone to do it.
However, when you account for the price of the hub and the labor expenses, you may conclude that it’s wiser to get a new wheel.