Bicycle Mechanics - "Cassette" vs. "Freewheel"...what's the difference?

The last time I had a multi-geared bike...1976...that thing with the five cogs on the rear wheel was called a "Freewheel".

http://fancyrobot.typepad.com/photos/uncategorized/dr_evil_1.jpg

You used a cylindrical piece of metal with two prongs on it...called a "Freewheel tool"...to remove it and you removed the "Freewheel" by placing the "Freewheel tool" into the two indentations on the "Freewheel" and locking it in place with the wheel's quick-release skewer. You could then use either a box wrench or a crescent wrench to finish the job.

Now that I've been unfrozen...MUHUHUHUHAHAHAHAHAHA...everyone's tossing around the term "cassette".

What's the difference?

A cassette is basically just sprockets and spacers. The ratcheting mechanism (free hub) is part of the hub.

With a cassette hub, the ratcheting mechanism (i.e. the freehub) is a more integral part of the hub. You can't install the axle without the freehub attached. You have to take out the axle to get the freehub off.

It's groovy, baby! :)

A cassette is basically just sprockets and spacers. The ratcheting mechanism (free hub) is part of the hub.
What's the advantage to this? Back in the "dark ages" I suppose it was possible to strip the freewheel threads on a hub but I'd never experienced it.

Is the free-hub permanentely attached to the hub? I take it that it's not.

I'm most familiar with Shimano. Others may not have all of these advantages...

1) Drive side hub bearings are actually in the freehub body which places them much further outboard than if they were in the hub body. This reduces the chance of breaking an axle. Especially important for MTBs and 8/9/10 speed road bikes.

2) The ratcheting mechanism wears out much less faster than cogs and you don't need to replace it every time you need a new set of cogs.

3) Uniform diameter. Allows the same freehub body to accept different speeds simply by changing spacer thickness. Early freehubs are 6/7-speed and current ones are 8/9/10 speed (although I think the Dura-ace 10-speed hub is 10-speed only because it has a special freehub body that accepts only 10-speed cassettes).

The freehub is usually attached to the hub shell with a "fixing" bolt. I think it's a 10mm allen bolt for Shimano. It's hollow to allow the axle to go thru.

With a cassette hub, the ratcheting mechanism (i.e. the freehub) is a more integral part of the hub. You can't install the axle without the freehub attached. You have to take out the axle to get the freehub off.

It's groovy, baby! :)
Is that reverse technology? Used to be you had to remove the freewheel to get the axle out.

Sound to me like the only advantage is the ability to quickly change out cassettes if that's an advantage.

I'm simply confused as to how this system is better than the old freewheels.

I'm most familiar with Shimano. Others may not have all of these advantages...

1) Drive side hub bearings are actually in the freehub body which places them much further outboard than if they were in the hub body. This reduces the chance of breaking an axle. Especially important for MTBs and 8/9/10 speed road bikes.

2) The ratcheting mechanism wears out much less faster than cogs and you don't need to replace it every time you need a new set of cogs.

3) Uniform diameter. Allows the same freehub body to accept different speeds simply by changing spacer thickness. Early freehubs are 6/7-speed and current ones are 8/9/10 speed (although I think the Dura-ace 10-speed hub is 10-speed only because it has a special freehub body that accepts only 10-speed cassettes).

The freehub is usually attached to the hub shell with a "fixing" bolt. I think it's a 10mm allen bolt for Shimano. It's hollow to allow the axle to go thru.
Ahhhhh........now I'm beginning to see how this works... :)

Is that reverse technology? Used to be you had to remove the freewheel to get the axle out.

There's rarely a need to take a freehub body off the hub. In ~20 years of using cassette hubs, I've think I've done it once when I converted a Uniglide hub to Hyperglide.

The Pontificato,

Cassette/freehub benefits:
- being able to replace just the cogs (as a whole or individually) and not the entire ratcheting mechanism
- moving the drive-side bearings outboard
- you can take cassettes apart and recombine in custom configs from corncob to megarange (11-34T)
- carrying an extra cassette on tour is a lightweight option; not so much with an extra freewheel

My last bike was a c.1991 touring bike with a 7-speed freewheel; current bike has an 8-speed freehub/cassette. Big leap forward IMO - not because of the extra cog (I could put a 7, 8 or 9-speed cassette on this freehub) but for all the other reasons listed above. :)

Sound to me like the only advantage is the ability to quickly change out cassettes if that's an advantage.

To me the biggie is that, because the drive side bearing is moved closer to the dropout, the axle is supported much better so you have fewer bent axle problems. I doubt that 8 and 9 free freweheel assemblies would work for very long without bending the axle.

Sheldon's site is all you need.

http://sheldonbrown.com/gloss_ca-g.html#cassette

Sheldon's site is all you need.

http://sheldonbrown.com/gloss_ca-g.html#cassette

EXCELLENT site! Thanks! Makes it all so much easier to understand esp. the schematic picture of Shimano's "freehub".

I suppose it was possible to strip the freewheel threads on a hub but I'd never experienced it.

I stripped a freewheel, it wasn't a good thing.

Sheldon's site is all you need.

http://sheldonbrown.com/gloss_ca-g.html#cassette
Yep; Sheldon's website is frequently all you need. LOTS of wisdom and wit there.

Of course, there is one drawback to the new mechanism: Lack of standardization. With the old system any freewheel would fit on any rear hub. That's not true with cassettes.

Of course, there is one drawback to the new mechanism: Lack of standardization. With the old system any freewheel would fit on any rear hub. That's not true with cassettes.

That's not quite accurate. On most hubs the threading was either the same or compatible. But a regular spaced 6-speed or 7-speed freewheel wouldn't fit on a 5-speed hub unless you changed the axle and increased the OLD. They weren't all drop-ins.

Customizing gearing or replacing the cogs without replacing the ratcheting mechanism was never a problem with freewheels back in their heyday. With the success of cassette hubs, freewheels have essentially been relegated to the status of one-shot consumables, but individual freewheel cogs used to be widely available.

While it is a practical advantage to cassettes in today's market, it has nothing directly to do with the technical advantages of a cassette (of which there are several). Of course, given the prices of a 9-speed cassette, that 7-speed freewheel starts to look like a bargain before too long!

That's not quite accurate. On most hubs the threading was either the same or compatible. But a regular spaced 6-speed or 7-speed freewheel wouldn't fit on a 5-speed hub unless you changed the axle and increased the OLD. They weren't all drop-ins.

Still, that's a lot easier and cheaper than replacing a wheel or relacing the wheel with a new hub.

I don't long for the return of the freewheel, but it sure would be nice to have interchangeable cassettes or freehub bodies.

Still, that's a lot easier and cheaper than replacing a wheel or relacing the wheel with a new hub.

I don't long for the return of the freewheel, but it sure would be nice to have interchangeable cassettes or freehub bodies.

Well, your right, cassettes/freehub bodies aren't interchangable among brands. Campy and Shimano have unique designs and the aftermarket suppliers like Mavic and American Classic have separate wheels for each brand. SRAM cassettes fit Shimano hubs so there is some commonality there.

However, among Shimano hubs, the freehub body can be changed easily and there are only two widths, 7-speed and 8/9/10-speed. I've converted 7-speed hubs to 8/etc.-speed and 8-speed back to 7-speed and it isn't difficult.

Customizing gearing or replacing the cogs without replacing the ratcheting mechanism was never a problem with freewheels back in their heyday. With the success of cassette hubs, freewheels have essentially been relegated to the status of one-shot consumables, but individual freewheel cogs used to be widely available.

I think that you might be suffering from selective memory. Sometimes swapping freewheel cogs, generally the larger sprockets, was simply a matter of spinning off the first two cogs and replacing what you wanted to replace. Othertimes, however, you had to contend with a daunting array of 1st and 2nd position cogs and spacers. The most common first two sprockets on common Shimano or Suntour freewheels were 14 and 17 and there weren't any options for those two positions. 52 X 14 = 100 GI. 52 X 17 = 83 GI. You want to go back to that?

Customizing gearing or replacing the cogs without replacing the ratcheting mechanism was never a problem with freewheels back in their heyday. With the success of cassette hubs, freewheels have essentially been relegated to the status of one-shot consumables, but individual freewheel cogs used to be widely available.

As RG pointed out, you appear to have selective memory. Indeed customized gearing, within limits, was available. I remember both Sun Tour and Shimano Cog Boards with every cog in their catalog on them. However, the individual cogs were priced so high that by the time you replaced two ot three cogs you paid as much as for a complete freewheel.

Complete cassettes can be quite economical if you avoid the top-of-the-line names and Ti cogs like Dura Ace or Record. Centaur and 105 cassettes are reasonably priced and excellent quality.

Modern indexing systems and their much stronger freehubs are so much better than their frewheel predicessors that I would never go back.

What's the advantage to this?

With a freewheel the axle has a longer unsupported section between the hub and the dropout. This makes it a lot easer to bend the axle. Nowadays, the bearings are integrated in the freehub body so the alxe has much less unsupported material. For example: you have a bike with a 6 speed freewheel threaded on to a hub. you unthread it and measure the distance from the locknut to the hub body. For our example we'll say it's 30 mm. With a freehub (cassette type) there may be only 10 mm from the lock nut to where the axle contacts the bearings through the cones. Thus, the necessary force to bend the axle is increased.