E-Bike Gear Upgrade: Switch From Freewheel To Cassette

Upgrading your e-bike’s drivetrain to a cassette system can offer several advantages, including smoother shifting, wider gear range, and compatibility with more advanced components. However, if your current setup uses a freewheel, making the switch requires a bit of know-how. In this guide, we’ll walk you through the process step-by-step.

Identifying Your Gear System: Cassette or Freewheel

Before replacing or upgrading your bike’s gear system, it’s essential to accurately identify whether it utilizes a cassette or a freewheel. Once you’ve identified your system, ensure you have the correct tools for removal and installation.

1. Examine the Hub Connection

• Freewheel: A freewheel directly screws onto the threaded hub of the rear wheel. It’s a self-contained unit that includes both the sprockets (gears) and the ratcheting mechanism.
• Cassette: A cassette is mounted onto a separate freehub body that’s attached to the hub. The freehub body contains the ratcheting mechanism, while the cassette itself is a stack of sprockets held together by a lockring.

2. Check for a Lock Ring

• Cassette: If you see a lock ring securing the gear cluster in place, it’s a strong indication of a cassette system. The lock ring is typically located on the outside of the smallest cog.

3. Inspect for Splines or Notches

• Freewheel: If you observe splines (internal ridges) or notches (external grooves) in a recessed area where a tool would attach to remove the gear cluster, it’s likely a freewheel. Different freewheel styles may have varying spline or notch patterns for tool engagement.

E-Bike Drivetrain Compatibility

Transitioning from a freewheel to a cassette often requires more than just replacing components. You’ll likely need to either replace the entire rear wheel with one designed for a cassette hub or rebuild your existing wheel with a new hub. This can be more complex and costly, so be prepared.

E-bike owners need to be especially careful, as the rear hub motor might be integrated with the freewheel. In this case, switching to a cassette could necessitate a whole new motor/wheel combo designed for cassettes. Always check with your e-bike or hub motor manufacturer to confirm compatibility and any specific requirements before attempting a conversion.

Simplifying Your Setup: Your Freewheel-To-Cassette Conversion Guide

Now that you’ve identified your system and confirmed compatibility, it’s time to roll up our sleeves and get started with the conversion! We’ll walk you through the step-by-step process of removing your existing freewheel and installing a shiny new cassette system!

Removing The Freewheel: The First Step To Cassette Conversion

1. Gather Your Tools

• Freewheel Removal Tool: This specialized tool is essential. Select the correct one based on your freewheel’s brand and type (spline or notch).
• Large Adjustable Wrench: You’ll need this to turn the freewheel removal tool.
• Axle Nut or Quick Release Skewer: This may be required to hold the tool in place for notch-type freewheels.
• Grease or Anti-Seize Compound: While primarily for installation, have it handy for later.

2. Identify Your Freewheel

• Splines or Notches: Check the center of the freewheel. It will either have internal ridges (splines) or external grooves (notches).
• Count or Measure: Count the number of splines to ensure you get the matching freewheel removal tool. If it’s a notch-type, measure the diameter across the notches to select the correct tool.

3. Remove the Rear Wheel

• Detach the wheel: Take the rear wheel off your e-bike.
• Remove axle nut or skewer: If it’s a standard axle, take off the nut. For quick-release, remove the skewer and its nut.

4. Engage the Freewheel Removal Tool

• Notch-type: Insert the tool into the notches. Use the axle nut or skewer to hold it firmly against the freewheel, preventing slippage.
• Spline-type: Insert the tool into the splines. The deeper fit usually makes extra securing unnecessary.

5. Remove the Freewheel

• Turn counter-clockwise: Use the wrench to turn the tool counter-clockwise. This loosens the freewheel. It might require significant force, especially if it’s old.
• Remove nut/skewer (if used): Once it’s loose, you can take off the nut or skewer if you used one to hold the tool.
• Keep turning: Continue until the freewheel is fully unthreaded from the hub.

6. Inspect & Prepare

• Check for damage: Look at the threads on the hub and the removed freewheel for any issues.
• Apply grease: Before installing the new cassette body, lightly grease the hub’s threads to prevent seizing and make future removal easier.

Installing Your New Cassette

Now that the freewheel has been removed, you’re ready to proceed with installing the cassette system. The cassette itself is simply a collection of cogs (the toothed wheels) that slide onto a special part of the hub called the “freehub”.

1. Prep the Cassette Body

• Clean the hub: Before installing the cassette or freehub body, clean the splines or threads on the hub where it will attach. This will ensure a good fit and prevent any debris from interfering.
• If needed, install it: Some e-bike conversion kits come with a cassette body pre-installed. If yours doesn’t, you’ll need to install one following the motor’s instructions. This usually involves threading it onto the hub and tightening it securely.
• A touch of grease: Apply a tiny bit of grease to the freehub body threads. This helps prevent seizing and makes future removal easier. Don’t overdo it, though, as excess grease can attract dirt.

2. Mount the Cassette

• Locate the widest slot on the freehub body. This should line up with the widest cog on your cassette. It’s helpful to position this slot at the top for easier alignment.
• If your cassette comes with a washer, slide it on first.
• Start by sliding the largest cog onto the freehub body.
• Follow with the remaining cogs, often held together by a plastic holder that you can remove before installation.
• Pay close attention to the placement of any spacers between the cogs. The first cog might not need one, but others will. Proper spacing is key for smooth shifting.
• Make sure the numbers indicating the number of teeth on each cog are facing outward.

3. Align & Secure

• As you slide the cassette on, ensure the ridges on the freehub body align perfectly with the notches on the cassette. There’s usually a distinct skinny ridge on the freehub that matches a skinny notch on the cassette.
• Place the lockring on top of the cassette. Use the lockring tool to screw it in by hand, being careful not to cross-thread it.
• After hand-tightening, use the adjustable wrench to further tighten the lockring. Aim for 8 to 10 Newton meters of torque (check your cassette’s instructions). You’ll feel a ratcheting sensation as the lockring’s teeth engage.

4. Finishing Touches

• Give the cassette a wiggle. If it moves, the lockring might not be on properly, so readjust it.
• Carefully put the wheel back on your e-bike, tighten the axle nuts or quick-release lever, and reattach the brake cable if needed.
• Give the cassette a spin to make sure everything is running smoothly.

Troubleshooting: Overcoming Cassette Conversion Challenges

Even with careful preparation, you might encounter a few bumps in the road during your freewheel-to-cassette conversion. Don’t worry! We’ve compiled a list of common challenges and their solutions to help you keep your project on track.

E-Bike Cassette Conversion Tips

• Hub Motor Compatibility: E-bikes with integrated hub motors present unique challenges for cassette conversions. Not all hub motors are compatible with cassettes, and some may require specific adapters or a complete wheel replacement. Check your motor’s specifications or consult the manufacturer to determine compatibility.
• Controller and Sensor Adjustments: Switching to a cassette system, especially if the number of gears changes significantly, might necessitate adjustments to your e-bike’s controller or sensors. Be prepared to recalibrate or reprogram these components to ensure proper functionality.
• Chain Length: Ensure your chain is the correct length for the new cassette setup. A chain that’s too long or too short can cause shifting problems or even damage your drivetrain. Use a chain length calculator or follow a simple formula to determine the ideal length.
• Derailleur Compatibility: The rear derailleur’s cage length determines its capacity to handle different cassette sizes. Make sure your rear derailleur is compatible with the number of speeds on your new cassette. If necessary, upgrade to a derailleur with a longer cage.

Remember

• Always disconnect your e-bike’s battery before working on any electrical components or the drivetrain.
• Choose a clean, well-lit, and organized work area to prevent accidents and keep track of small parts.
• Wear safety glasses and gloves to protect yourself from potential injuries.
• Using the correct tools is essential to avoid damaging your bike and ensure a successful conversion.