E-Bike Freehub Body Replacement: The Lightning-Fast Pro Guide

For many years, freehub standards remained relatively unchanged, with a single design dominating the market. However, recent innovations have introduced multiple freehub body designs, creating some confusion about how to remove and replace these components across different bike systems. In this article, we’ll break down the three main freehub standards, how to identify them, and step-by-step instructions on how to switch them out safely.

The Indispensable Freehub Body

A freehub body is a ratcheting mechanism found in the hub of your bike’s rear wheel. This is the part that allows the cassette (the cluster of sprockets) to slide on and lock in place. Unlike older systems where cogs were screwed directly onto the hub, modern freehubs provide a more efficient, adaptable, and smoother operation. When the freehub body is engaged, the pawls inside it allow the bike to move forward, and when the rider stops pedaling, the pawls disengage, allowing the wheel to spin freely.

Freehub Standards: The Big Three

There are currently three main freehub body standards that you are likely to encounter, each with its own characteristics and compatibility.

1. Shimano Hyperglide (HG): The most prevalent standard, compatible with 6 to 11-speed systems and even some 12-speed setups. You can easily recognize it by its distinct pattern of alternating narrow and wide splines on the freehub body.
2. SRAM XD: SRAM introduced this standard to support the smaller 10-tooth cogs, which are often used in 1x drivetrains (single chainring setups). This design has a noticeably smaller diameter at the end compared to HG, and the cassette threads directly onto it instead of sliding on. It’s popular among mountain bikes, particularly those with 1x drivetrains, due to its compatibility with smaller gear ratios.
3. Shimano Microspline: This is Shimano’s latest standard, designed primarily for their 12-speed mountain bike groupsets. This system features deeper splines than Shimano Hyperglide to securely hold the cassette and requires special Microspline-compatible end caps on the hub. While primarily used on 12-speed MTB drivetrains, it might expand to other drivetrain categories in the future.

Identifying Your Freehub Body Type

Before initiating any work, it’s crucial to identify your bike’s freehub standard. This can be achieved by removing the cassette and visually inspecting the freehub body. Each standard exhibits distinctive spline or threading patterns, making identification relatively straightforward.

Step-by-Step Freehub Body Removal & Replacement

Once you’ve correctly identified your freehub type, it’s time to proceed with its removal and replacement if necessary. The following guide outlines the general procedure applicable to most freehub systems. Notably, many hubs, including widely-used options like DT Swiss, offer convenient interchangeability between various freehub types. Depending on the specific hub model, the entire swapping procedure can typically be completed within 1 to 10 minutes.

Tools Required

• Cassette lockring tool (also used for disc rotors)
• Chain whip
• 17mm & 15mm spanners (cone spanners/wrenches)
• Lever or jolly bar (for extra leverage, optional)
• 10mm Allen key (for freehub body bolt)
• T25 or 3mm Allen key (for disc rotor bolts, if applicable)
• Magnetic pickup tool
• Cloth or paper towel
• Grease
• Vice (optional, for stability)

1. Cassette & Disc Rotor Removal

1. Remove the wheel from the bike.
2. If present, remove the quick-release skewer or undo the wheel nuts to detach the wheel.
3. Use the chain whip to hold the cassette steady and the cassette lockring tool to loosen and remove the lockring counterclockwise. If the lockring is tight, maintain even pressure in a “10 to 2” position on the tool to avoid slipping.
4. Remember: SRAM XD cassettes come off as one piece, while Shimano HG or Microspline cassettes will separate into individual cogs and spacers. Keep these organized in the order they came off.
5. If your bike has disc brakes, use the appropriate Allen key (T25 or 3mm) to remove the disc rotor bolts or lockring. Handle the rotor carefully by its edges to avoid contaminating the braking surface.

2. Hub Disassembly & Freehub Removal

1. If using a vice, secure the wheel with the freehub side facing outwards.
2. Use the 15mm cone spanner to hold the cone steady on the non-drive side.
3. With the 17mm spanner, turn the locknut counterclockwise to loosen and remove it.
4. Slide off the locknut, spacer, and the left-hand side cone from the axle.
5. Carefully pull out the axle. Use the magnetic pickup tool to gather any loose ball bearings from both bearing cups (typically 9 per side).
6. Locate the end cap on the drive side (the side with the sprockets) of the hub. This end cap may simply pull or slide off, or it might require a specific tool depending on the hub design. Some end caps have markings indicating the compatible freehub standard (e.g., “XD” or “Microspline”).
7. Insert the 10mm Allen key into the freehub body and turn it counterclockwise to unscrew and remove the fixing bolt.
8. Detach the freehub body. Be aware that small internal parts like pawls and springs might come loose. Use a magnet to retrieve them if they do.
9. Thoroughly clean the washer, axle, and hub area before reassembly.

3. New Freehub Body Installation & Hub Reassembly

1. Ensure the hub area and axle are clean.
2. If you’re changing freehub standards, make sure to install any necessary adapter spacers first
3. Place the freehub body washer in its designated position.
4. Carefully slide the new freehub body onto the axle, making sure it engages properly with the internal mechanism. You might need to apply a bit of pressure and rotate the freehub slightly to fully seat it.
5. Insert the fixing bolt and tighten it securely with the 10mm Allen key (clockwise).
6. Apply grease to the freehub’s bearing cup and place the ball bearings into it. Wipe away any excess grease from the freehub body
7. Clean and regrease the bearing cup on the non-drive side and replace its bearings
8. Reinsert the axle into the hub (or slide the wheel back onto the axle if using a vice)
9. Reinstall the cone by hand until it contacts the bearings
10. Put the correct end cap back on the hub. Double-check that it matches the freehub standard you’re using.
11. Put the spacer and locknut back on the axle
12. Use the 15mm cone spanner to hold the cone and the 17mm spanner to tighten the locknut (clockwise).
13. Spin the axle – it should rotate freely without any play or looseness
14. If there’s excessive play or the axle doesn’t spin smoothly, adjust the locknuts and cones
15. Use the 17mm spanner to hold one side steady, and turn the other side’s cone slightly (about 1/4 turn) with the 15mm spanner. Repeat this process on both sides until the axle’s movement is satisfactory

4. Cassette & Disc Rotor Reinstallation

1. Slide the cassette onto the new freehub body
2. For HG and Microspline systems, pay close attention to the order of the cogs and spacers.
3. Thread the lockring on by hand, then use the lockring tool to tighten it to the manufacturer’s specified torque. Avoid overtightening, which can damage the freehub or cassette.
4. Reinstall the disc rotor (if applicable), ensuring bolts or lockring are tightened properly
5. Reattach the quick-release skewer or reinstall the wheel nuts
6. Mount the wheel back on your bike

Remember to test the new freehub by spinning the wheel and listening for any unusual noises or friction.

The DT Swiss Star Ratchet System

DT Swiss employs a distinctive Star Ratchet system, where the ratchets engage with the axle in a parallel orientation rather than the perpendicular arrangement found in most other systems. The DT Swiss Star Ratchet comes in different versions, such as the Ratchet EXP and Ratchet LN, which may or may not be compatible with other systems. It’s important to check the DT Swiss website to verify compatibility if you’re considering switching ratchet systems.

E-Bike Freehub Maintenance Tips: Grease, Pawls & Springs

Proper freehub maintenance is essential for a smooth and long-lasting ride. While it’s tempting to generously grease every part during servicing, remember that over-greasing can be detrimental, especially for the delicate pawls and springs.

Do’s

• Lightly grease the splines and threads of the freehub body to prevent corrosion and ensure smooth installation of the cassette.
• Check the condition of the bearings. If they aren’t too worn, you can add a small amount of grease to prolong their life.

Don’ts

• Avoid applying thick grease to the pawls and springs. These components rely on being able to move freely; too much grease can cause them to stick, leading to engagement issues.
• Some manufacturers recommend using light oil rather than grease in certain areas to ensure pawls and springs can function without restriction.

Freehub Body Replacement Upgrades

Whether replacing a worn freehub or upgrading to a new standard, understanding freehub body types and their maintenance is key to a smooth-running drivetrain. By following these guidelines and exercising care, you can avoid common pitfalls and enjoy the benefits of a well-maintained e-bike.