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.
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