Accessories Bicycles Parts Specials Tools

Search sheldonbrown.com and sheldonbrown.org

Freewheel or Cassette?
When it comes time to service or upgrade your bike, it is important to know which of these two systems is used on your bike.

@sheldonbrowncom
Sheldon Brown photo
by Sheldon "Kah Sept" Brown
Spoke Divider

Freewheels and Cassette Freehubs

They're NOT the same!

This particular page is intended to help you determine which type your bike is equipped with, because there is a great deal of confusion about which is which.

The terms "freewheel" and "cassette" are often used interchangeably, an error that causes a lot of wasted time and money.

Freewheels for Threaded Hubs:

Traditional rear hubs came with a standardized set of threads to which a standard freewheel/sprocket cluster could be screwed on. This allowed any brand of freewheel to be mounted on any brand of hub. If you wore out your sprockets, or wanted different gear ratios, you could unscrew the cluster and install a new one.

Almost all bikes made through the late 1980s used this system.

Cassette Freehubs

Over the last few years the Shimano "Freehub" has largely replaced the conventional threaded rear hub. These hubs work so well that they have come to represent the new "standard."

Most decent-quality bikes made since the late 1980s have used this greatly improved design.

Spoke Divider

Spoke Divider

Freewheel vs Cassette
Traditional
Threaded Freewheel
Traditional
Threaded Hub
Cassette Freehub Cassette Cluster

The cassette Freehub incorporates the ratchet mechanism into the hub body (although the ratchet mechanism is still replaceable). When you wear out the sprockets on a Freehub, you replace the sprockets only, not the ratchet mechanism (which typically lasts much longer than the sprockets).

The sprockets are commonly sold as a set, called a "cassette". The sprockets in a cassette are usually held together by three small bolts or rivets for ease of installation. These bolts or rivets are by no means necessary, they just make it easier to keep the sprockets and spacers in the correct order and position when they are removed from the ratchet body. Individual sprockets are also available.

SRAM, Sturmey-Archer, and other common brands have adopted the Shimano Freehub design, and their cassettes are interchangeable. Campagnolo and Mavic products are not.

Spoke divider

The purpose of this page is to help you distinguish one type from the other.

This site also contains much more detailed articles on both Freewheels and Cassettes, explaining the pros and cons of each system.

Spoke Divider

Spoke Divider

Identification: Freewheel or Cassette?

frwl-sachs frwl-shimano frwl-suntour k7hub-lockring
Sachs (Sram) Freewheel Shimano Hyperglide Freewheel Sun Tour Two-notch Freewheel Cassette with Lockring
(Click for details)

Freewheels

  • Commonly 5-, 6- or 7-speeds
  • Extractor splines do not turn when sprockets are spun backwards

Cassettes

  • Commonly 7-, 8-, 9- or 10-speeds
  • Lockring splines turn with sprockets when spun backwards
  • Many cassette Freehubs have a distinctive bulge on the right end of the hub barrel.

Spoke divider

Shimano Freehub with Bulge

Shimano Cassette Freehub, showing characteristic bulge on the right side of the body.

Not all Freehubs have this bulge, but whenever you see it, you can be sure that it is, in fact, a cassette Freehub.

Spoke Divider

Spoke Divider

Articles by Sheldon Brown and others
Harris
Home
Beginners Brakes Commuting
Lights
Cycle-
Computers
Do-It-
Yourself
Essays
Family
Cycling
Fixed Gear
Singlespeed
Frames Gears &
Drivetrain
Bicycle
Humor
Bicycle
Glossary
Bicycle
Links
Old
Bikes
Repair
Tips
Tandems Touring What's
New
Wheels Sheldon
Brown

Accessories Bicycles Parts Specials Tools

Copyright © 2005, 2008 Sheldon Brown

Harris Cyclery Home Page

If you would like to make a link or bookmark to this page, the URL is:
http://sheldonbrown.com/free-k7.html
Last Updated: by John Allen