The Secret of Smooth Rotation Lies in Tiny Bearings
Bearings are one of the most overlooked yet most important components on a bicycle. Your hubs, bottom bracket, headset, and pedals all contain bearings — they determine how smoothly your bike rolls.
Types of Bearings
| Type |
Structure |
Characteristics |
Common Locations |
| Loose ball bearings |
Steel balls rolling in cup-and-cone races |
Adjustable, serviceable |
Older hubs, pedals |
| Sealed bearings |
Steel balls inside a sealed cartridge |
Maintenance-free, replaced as a unit |
Modern hubs, bottom brackets |
| Ceramic bearings |
Ceramic balls replace steel balls |
Harder, rounder, more durable |
High-end wheelsets, bottom brackets |
Sealed Bearings vs. Loose Ball Bearings
| Comparison |
Sealed Bearings |
Loose Ball Bearings |
| Maintainability |
Replace the whole unit when worn |
Can be cleaned and regreased |
| Water resistance |
Better |
Weaker |
| Adjustability |
Not adjustable |
Play can be adjusted |
| Lifespan |
Moderate |
Can be very long with good maintenance |
| Cost |
Pricier per unit |
Steel balls are cheap |
Are Ceramic Bearings Worth It?
| Pros |
Cons |
| Lower friction |
Priced 5-10 times more than steel |
| Harder and rounder |
More sensitive to contamination |
| Theoretically more durable |
Requires more precise maintenance |
| Psychological sense of speed |
Real-world difference is within 1-2W |
Conclusion: For 99% of riders, good quality steel sealed bearings are enough. The performance difference from ceramic bearings is minimal, but the psychological boost is significant.
Bearing Lifespan
| Location |
Expected Lifespan |
| Hubs |
5,000-15,000 km |
| Bottom bracket |
5,000-10,000 km |
| Headset |
10,000-20,000 km |
| Pedals |
5,000-15,000 km |
Taiwan’s humid climate may shorten lifespan by 30-50%.
Signs of Bearing Damage
| Signal |
Severity |
| Gritty feeling when spinning |
⚠️ Time for maintenance or replacement |
| Unusual noise when spinning |
⚠️ Needs inspection |
| Noticeable play (wobble) |
🔴 Needs adjustment or replacement |
| High resistance when spinning |
🔴 Bearing damage |
| Rust |
🔴 Replace immediately |
Bearing Replacement
Replacing sealed bearings requires knowing the bearing’s specification number (e.g. 6802, 6902, etc.). Simply take the old one to a hardware store or bike shop for a match.
| Installation Method |
Approach |
| Press-fit |
Use a bearing press tool, or a bolt and washers to press it in slowly |
| Pull-out |
Use a bearing puller, or gently tap the edge to remove it |
Taboo: Never strike the center of the bearing directly with a hammer! This will damage the bearing’s inner and outer races and the balls.
Choosing Bearing Grease
| Grease Type |
Suitable For |
| General lithium-based grease |
Most situations |
| Waterproof grease (Phil Wood) |
Recommended for Taiwan’s humid climate |
| Ceramic bearing specific grease |
Ceramic bearings |
| Low-temperature grease |
Winter or high altitude |
Bearings aren’t expensive — around NT$50-300 each (ceramic excluded). But when they fail, they affect the entire system’s operation. Regular inspection and timely replacement is the smartest investment.