What is Chain Wear? Chain Stretch Explained
Chain wear (chain stretch) occurs as pins and rollers wear, elongating the chain. Learn how to measure chain wear and when to replace your bike chain.
Quick Answer
Chain Wear — (often called "chain stretch") occurs when the pins and rollers inside your bike chain wear down, causing the chain to effectively lengthen. At 0.5% wear (0.5mm stretch per 100mm), you should replace your chain to prevent cassette damage. At 0.75-1.0% wear, both chain and cassette typically need replacement.
What Causes Chain Wear?
Chain "stretch" isn't actually stretching—it's wear between internal components:
| Component | Wear Effect |
|---|---|
| Pins | Wear thinner, creating play |
| Rollers | Wear smaller, increasing gap |
| Bushings | Wear creates slack |
The cumulative effect: each link becomes slightly longer, and the chain "grows."
Chain Wear Thresholds
| Wear Level | Measurement | Action Required |
|---|---|---|
| 0.5% (0.5mm/100mm) | New chain time | Replace chain only |
| 0.75% (0.75mm/100mm) | Overdue | Replace chain, check cassette |
| 1.0% (1.0mm/100mm) | Critical | Replace chain AND cassette |
How to Measure Chain Wear
Method 1: Chain Checker Tool
- Place tool on chain
- Insert measuring tip into link
- Read wear percentage on gauge
- Replace if at 0.5% or higher
Method 2: Ruler Method
- Align ruler at a pin starting at 0"
- Check where the 12" mark lands
- Should align perfectly with a pin center
- 1/16" past = 0.5% wear
- 1/8" past = 1.0% wear
Chain Wear by Riding Conditions
| Conditions | Expected Life |
|---|---|
| Clean, road, good lube | 3,000-5,000 miles |
| Mixed conditions | 2,000-3,000 miles |
| Wet/muddy, MTB | 1,000-2,000 miles |
| E-bike (high torque) | 1,500-2,500 miles |
Why Chain Wear Matters
A worn chain damages your cassette and chainrings:
- Worn chain + new cassette = Skipping, poor shifting
- New chain + worn cassette = Chain skips under load
- Both worn together = Work fine but wearing faster
Replacing the chain at 0.5% wear saves your cassette (which costs 3-5x more than a chain).
Factors That Accelerate Wear
| Factor | Impact |
|---|---|
| Dirty chain | High - grit acts as sandpaper |
| Wrong lube | High - inadequate protection |
| Cross-chaining | Medium - increased friction |
| High torque (e-bike, climbing) | Medium - stress on pins |
| Wet conditions | Medium - washes away lube |
Preventing Premature Wear
- Clean regularly - Every 100-200 miles
- Lube properly - Right lube for conditions
- Avoid cross-chaining - Don't use extreme gear combos
- Replace at 0.5% - Don't wait until it's too late
- Wipe after wet rides - Remove moisture and grit
When replacing a worn chain, use our Bicycle Chain Length Calculator to size your new chain correctly.