[HOW TO] Easily Identify Cassette vs. Freewheel On Your Bike

Cassettes and freewheels are the mechanisms on your bike’s rear wheel that house the gears, allowing you to shift and pedal efficiently across various speeds and terrains. Before any replacement or upgrade to your bike’s gearing, it’s essential to identify whether you have a cassette or a freewheel. This knowledge will directly determine the correct tools and components you’ll need for the task.

Identifying Your Bike’s Gear System: A Step-by-Step Guide

To accurately determine if your bike has a cassette or freewheel system, we’ll start by getting a clear view of the rear wheel hub. Then, a quick visual check will reveal whether your bike uses a cassette (look for a lockring) or a freewheel (look for recessed splines).

1. Removing the Rear Wheel

Start by carefully detaching the rear wheel from your bike. This will give you a clear view of the sprockets (the gears) and the hub for identifying your gear system. Before you remove the wheel, make sure your bike is stable and secure, either by using a bike stand or carefully leaning it against a wall. This will prevent any accidents or damage to your bike during the process.

• Quick Release: If your bike has a quick-release skewer, simply open the lever, unscrew the nut slightly, and pull the skewer out to remove the wheel.
• Bolt-On Axle: If your bike has a bolt-on axle, you’ll need the appropriate wrench to loosen and remove the nuts securing the wheel to the frame.

2. Spinning the Sprockets

Once the rear wheel is removed, gently rotate the sprockets counter-clockwise, the opposite direction of normal pedaling. Observe the tool fitting – the specific area where a tool would engage to remove the sprockets.

• Cassette System: If the tool fitting rotates in unison with the sprockets when spun backward, your bike employs a cassette system. This synchronized movement occurs because in a cassette system, the sprockets (collectively known as the “cassette stack”) are independent of the ratcheting mechanism, which is integrated into the hub body, referred to as the “freehub.”
• Freewheel System: If the tool fitting remains stationary while the sprockets spin backward, your bike is equipped with a freewheel system. In this configuration, the sprockets and the ratcheting mechanism are combined into a single unit that threads directly onto the hub. The immobile tool fitting during sprocket rotation is a telltale sign of a freewheel.

3. Visual Inspection: Additional Clues

Before you even grab your tools, a quick visual inspection of your bike can often provide valuable clues about its gear system.

• Number of Gears: If your bike has a high number of gears (typically 8 or more), it’s almost certainly a cassette system. Freewheels typically max out at 7 gears.
• Lockring vs. Recessed Splines
  • Cassette: Look for a visible lockring with notches around its circumference. This is a strong indicator of a cassette system.
  • Freewheel: If you see a recessed area with splines (internal teeth) instead of a lockring, it’s likely a freewheel.

4. Examining the Innermost Tool Fitting

Now that you’ve observed how the tool fitting interacts with the sprockets, let’s take a closer look at the innermost tool fitting itself. This will provide further confirmation of whether you have a cassette or a freewheel system.

• Cassette System: The innermost fitting for a cassette system is usually located on the lockring that secures the cassette stack to the freehub. As you spin the sprockets, this fitting will move with them, confirming it as a cassette. For example, on many Shimano, SRAM, or Sun Race cassettes, the lockring has 12 internal splines that match the pattern of the freehub.
• Freewheel System: In a freewheel system, the innermost fitting is part of the freewheel body and does not move when the sprockets are spun backward. Freewheels may have different types of innermost fittings, such as splines or notches, depending on the manufacturer. For instance, a freewheel might have 12 or 20 splines or various notches that do not rotate with the sprockets, indicating a freewheel.

5. Tool Selection Based on System Type

Now that you’ve successfully identified whether your bike has a cassette or a freewheel, the next crucial step is selecting the right tool for removal and installation. The specific tool required will depend on the brand and design of your cassette or freewheel.

Cassette Systems

• Most Brands: For common brands (Shimano, SRAM or SunRace), you’ll typically use a standard cassette lockring tool and a chain whip.
• Campagnolo: Campagnolo cassettes have a unique spline pattern, so you’ll need a specific Campagnolo cassette lockring tool.
• XD Driver: Some SRAM cassettes use an XD Driver freehub body. While the cassette itself may use a standard lockring tool, removing the XD Driver body requires a specialized tool.

Freewheel Systems

To choose the right freewheel removal tool, identify the type and number of splines or notches on the innermost part of the freewheel.

• Splined Freewheels: You’ll need a freewheel removal tool that matches the number of splines on your freewheel (e.g., a 20-spline freewheel requires a compatible 20-spline freewheel removal tool). If unsure, consult the freewheel’s specifications or measure the spline diameter to determine the appropriate tool.
• Notched Freewheels: If your freewheel has notches instead of splines, you’ll need a specific notch-type freewheel removal tool. Count the number of notches and measure their diameter to select the correct tool.

6. Proceeding with Replacement or Conversion

Once you’ve correctly identified your bike’s gear system and have the appropriate tools at hand, you’re ready to proceed with the replacement or conversion. Whether you’re simply replacing a worn-out component or making a more significant transition between a freewheel and a cassette system, having the right tools is essential to ensure a successful process and protect your bike’s components from any accidental damage.

Compatibility Issues: Please note that it’s not possible to install a freehub (which holds a cassette) onto a hub designed for a freewheel. Thus, converting from a freewheel to a cassette requires either replacing the entire wheel or rebuilding it with a new hub, which may not be cost-effective.