• A Clean Workspace
  • Two 17mm Cone Wrenches
  • 11mm Allen Key
  • Rubbing Alcohol
  • Clean Rags
  • Grease
  • Various Chromag Hub Parts Kits, depending on the type of service to be performed

The steps outlined below are for a general hub service and clean, which will greatly increase the life of your hub.

To replace bearings we recommend using a quality bike shop. If you are comfortable with changing bearings and have the appropriate tools, please reach out to us if you have any questions.


  1. While holding one end cap in place with a 17mm cone wrench, twist the other end cap loose with the other 17mm cone wrench. Remove the end cap and set aside. Take note which side it came from.
  2. Insert the 11mm Allen key into the now-exposed end of the hub axle. Use this to hold the axle from rotating as you twist the second end cap loose with a 17mm cone wrench. Note: Both end caps may loosen during step 1, in which case simply unscrew both end caps by hand.
  3. Grasping the freehub in one hand and the hub body in the other, pull the freehub assembly away from the hub and slide it off the axle. The freehub assembly may require significant force to dislodge, especially with a newer hub, due to the rubber seal ring. Be sure not to lose the small steel washer that spaces the inner freehub bearing and the outer hub bearing.

From here, inspect all hub components with the bearings still installed.

  • Hold the hub body and spin the axle. If you feel resistance, grinding, or axial and/or lateral play, you should perform the hub body service and replace the hub bearings.
  • Inspect the freehub body and all freehub components for wear. Check each pawl and pawl spring for wear or damage. Spin each bearing and ensure smooth operation. If you notice any damage or bearing resistance, you should perform the freehub service and replace the freehub bearings.
  • Using rubbing alcohol and a rag, wipe down the axle, ratchet ring, bearings and pawls/springs.
  • The pawls and springs can be removed for easier cleaning. Take note the orientation in which they were installed.
  • Gather any replacement parts for reassembly. Replacement parts kits can be purchased from Chromag.


  1. Slide the steel washer onto the drive-side of the axle.
  2. Apply grease to the axle. 
  3. Use a light grease on the pawls and ratchet ring.
  4. Slide the freehub assembly onto the axle. Depress the four pawls while sliding the assembly into the ratchet ring. Note: if you have difficulty pressing all four pawls in at the same time, wrap a piece of wire or string around the pawls to depress them.
  5. Press the rubber seal ring into the groove around the freehub body.
  6. Reinstall the end caps using two 17mm cone wrenches.

Click here to download the R4 rear exploded view.