Decoding Bicycle Bearing Codes
Decoding Bicycle Bearing Codes: Your Complete Guide to Understanding What Those Numbers Mean!
Published: Monday, June 9th, 2025
If you've ever looked at a bicycle bearing and wondered what all those numbers and letters mean, you're not alone. Bearing codes might seem like a mysterious language, but once you crack the code, they become an invaluable tool for maintenance, replacement, and upgrades.
What Are Bearing Codes?
Bearing codes are standardized identification systems that tell you everything you need to know about a bearing's specifications. Think of them as a bearing's DNA – each code reveals the bearing's size, type and performance characteristics.
The Anatomy of a Bearing Code
Most bicycle bearings follow the ABEC (Annular Bearing Engineering Committee) or ISO standards. Here's how to read them:
Standard Format:
[Series][Bore Diameter/Inner Diameter][Suffix]
Example: 6902-2RS
- 69 = Series number (indicates the bearing type and proportions)
- 02 = Bore diameter code (15mm in this case)
- 2RS = Suffix indicating seals (2 Rubber Seals)
Common Bearing Series in Cycling
60 Series (Single Row Deep Groove Ball Bearings)
- 6000: 10mm bore, 26mm outer diameter
- 6001: 12mm bore, 28mm outer diameter
- 6002: 15mm bore, 32mm outer diameter
61 Series (Extra Light)
- 6100: 10mm bore, 19mm outer diameter
- 6101: 12mm bore, 21mm outer diameter
69 Series (Thin Section)
- 6900: 10mm bore, 22mm outer diameter
- 6901: 12mm bore, 24mm outer diameter
- 6902: 15mm bore, 28mm outer diameter
70+ Series (Single Row Deep Groove Angular Contact Ball Bearings)
- 7000: 10mm bore, 26mm outer diameter
- 7901: 12mm bore, 24mm outer diameter
- 7902: 15mm bore, 28mm outer diameter
Bore/ Inner Diameter Codes
| 00 | 10mm |
| 01 | 12mm |
| 02 | 15mm |
| 03 | 17mm |
| 04 | 20mm |
| 05 | 25mm |
| 06 | 30mm |
| 07 | 35mm |
| 08 | 40mm |
| 09 | 45mm and so on.... |
Decoding the Suffixes
The suffix tells you about seals and materials:
- 2RS: Double rubber sealed (most common for bikes)
- LLB: Low Contact Seals
- LLU: Medium Contact Seals
- MAX: Enduro's maximum capacity bearing
- SS: Stainless Steel
UK-Specific Considerations
Our wet, muddy conditions means that paying attention to seal codes is crucial:
- 2RS bearings offer better protection against water ingress
- LLB seals provide smoother rolling but less weather protection
- MAX bearings handle the extra stress from muddy, technical UK trails
Tips for Bearing Code Success
- Always double-check – Measure your old bearing if unsure
- Consider your riding style – Aggressive riders need MAX bearings
- Think about conditions – Wet riders prioritize sealing
- Keep a reference – Save common codes for your bike
When Codes Don't Match
Sometimes manufacturers use their own system that differs slightly from the standard. If you can't find a standard code:
- Measure the bearing dimensions
- Check manufacturer specifications
- Contact us – we can help identify mystery bearings!
Need help identifying your bearing codes? Our bearing experts are here to help. Use our search function with your bearing code, put the dimensions into the Bearing Code generator above or chat with us for personalized advice.
Next week: We'll dive into the differences between angular contact bearings and radial bearings!