How to Determine the Right Size Bearings for Your Front or Rear Hub and Bottom Brackets

How to Determine the Right Size Bearings for Your Front or Rear Hub and Bottom Brackets

Selecting the correct bearings for your bike’s front or rear hub and bottom brackets is crucial for optimal performance and longevity. This guide will help you navigate through the process, ensuring you get the right fit every time.

Understanding Bearing Sizes

Bearings come in various sizes, and each type is suited for specific components of your bike. The size of a bearing is typically indicated by three numbers that correspond to the bearing's internal diameter (ID), outer diameter (OD), and width. For example, a bearing labeled 61803 has an ID of 17mm, an OD of 26mm, and a width of 5mm. You can find a conversion table show the bearing dimensions of available sizes below:

Inner Diameter Outer Diameter Bearing Width
61800 10 19 5
61801 12 21 5
61802 15 24 5
61803 17 26 5
61900 10 22 6
61901 12 24 6
61902 15 28 7
61903 17 30 7

Tools You’ll Need

  1. Calipers: For precise measurements of your current bearings.
  2. Bearing puller: To safely remove old bearings.
  3. Bike manual: Often, manufacturers provide specific bearing sizes required for each model.
  4. Cleaning supplies: To clean the hub or bottom bracket before installing new bearings.

Step-by-Step Guide

1. Remove the Old Bearings:

- Start by removing the wheel or crankset to access the hub or bottom bracket.
- Use a bearing puller to carefully extract the old bearings. Avoid using excessive force to prevent damage.

2. Measure the Bearings:

- With the old bearings removed, use a caliper to measure the ID, OD, and width. Ensure your measurements are precise to avoid incorrect sizing.
- Note down the bearing number if it’s visible. This can be cross-referenced with your measurements to confirm accuracy.

ID = Inner Diameter:

OD = Outer Diameter:


3. Consult Your Bike’s Manual:

- Refer to your bike’s manual for bearing specifications. Manufacturers usually list the recommended bearing sizes for different components.
- If you don't have the manual, check the manufacturer’s website or contact customer support for guidance.

4. Consider the Environment:

- Think about the riding conditions. If you often ride in wet or muddy environments, opt for bearings with contact outer seals to prevent contamination.
- Road bikers should go for no-contact outer seal bearings for their lower drag torque characteristics.

5. Purchase the Correct Bearings:

- Once you have the measurements and specifications, cross reference with the size chart available on the Eenox website to determine what size bearings you need.

6. Install the New Bearings:

- Clean the hub or bottom bracket thoroughly before installation.
- Gently press the new bearings into place using appropriate tools to avoid damaging them.
- Reassemble the wheel or crankset, ensuring everything is securely fitted.

Common Bearing Sizes

Every bike is different, but here are some common bearing sizes used in bike hubs and bottom brackets:

  • Front Hub Bearings:
    • 61802 (15x24x5 mm)
    • 61803 (17x26x5 mm)
  • Rear Hub Bearings:
    • 61902 (15x28x7 mm)
    • 61903 (17x30x7 mm)
  • Bottom Bracket Bearings:
    • 61805 (25x37x7 mm)
    • 61806 (30x42x7 mm)

Tips for Maintenance

  • Regular Inspections: Periodically check your bearings for signs of wear or damage.
  • Proper Lubrication: Ensure your bearings are well-lubricated to reduce friction and extend their lifespan.
  • Cleanliness: Keep your bike clean, especially after riding in harsh conditions, to prevent dirt and moisture from affecting the bearings.

How To Determine the Right Size Bearings For Your Bike

By following this guide, you can accurately determine the correct size and ensure your bike remains in peak condition. Whether you're replacing old bearings or upgrading to high-performance ones, Eenox bearings will enhance your riding experience.