Power Meter
A power meter measures your cycling power output in watts. Learn how power meters work, different types available, and why power training is valuable for cyclists.
Quick Answer
Power Meter — A power meter is a device that measures how much power (in watts) you produce while cycling. It uses strain gauges to measure force and combines it with angular velocity to calculate power. Power meters enable precise training, pacing, and performance tracking.
What is a Power Meter?
A power meter directly measures your cycling output using:
Power Formula:
Power (W) = Torque (Nm) × Angular Velocity (rad/s)
Or practically:
Power (W) = Force × Distance / Time
Power meters measure the force you apply to the pedals and calculate power in real-time.
Why Power Matters
| Advantage | Compared to Heart Rate |
|---|---|
| Instant feedback | No 30-60 second lag |
| Objective | Not affected by caffeine, heat, fatigue |
| Reproducible | 200W is 200W, always |
| Precise training | Exact zone targeting |
| Pacing | Know exact output in races |
Read our complete guide: Cycling FTP Guide.
Types of Power Meters
Crank-Based
| Type | Measures | Pros | Cons |
|---|---|---|---|
| Spider | Force at chainrings | Accurate, durable | Expensive |
| Crank arm | Force in crank | Mid-price, dual available | May need matching arm |
| Spindle | Force at bottom bracket | Accurate | Complex installation |
Pedal-Based
| Pros | Cons |
|---|---|
| Easy to swap bikes | Battery life |
| Easy installation | Weight on rotating mass |
| Dual-sided common | Stack height issues |
Hub-Based
| Pros | Cons |
|---|---|
| Measures all power | Tied to one wheel |
| Very accurate | Heavy, not transferable |
| Robust | Less common now |
Smart Trainers
| Pros | Cons |
|---|---|
| Indoor training | Indoor only |
| Often included | Need separate outdoor meter |
| Very accurate | Not for outside |
Single-Sided vs Dual-Sided
| Factor | Single-Sided | Dual-Sided |
|---|---|---|
| Price | Lower | Higher |
| Accuracy | ±1-2% (assumes 50/50) | True left/right |
| Data | Total power only | L/R balance |
| For most riders | Sufficient | Nice to have |
Single-sided meters double one leg's power, assuming 50/50 split. If your balance is 48/52, error is ~4%.
Accuracy and Calibration
Accuracy Specifications
| Accuracy | Typical Devices |
|---|---|
| ±1.0% | High-end spider/spindle meters |
| ±1.5% | Quality crank/pedal meters |
| ±2.0% | Entry-level meters |
| ±3-5% | Budget options |
Calibration
| Type | Frequency |
|---|---|
| Zero offset | Every ride (1-2 min process) |
| Temperature change | After significant temp change |
| Firmware updates | When available |
| Factory calibration | Rarely needed |
Using Power for Training
FTP Testing
Power meters enable accurate threshold testing:
- 20-minute test × 0.95 = FTP
- Ramp test protocols
- Regular retesting
Use our FTP Calculator.
Training Zones
Power-based zones are more precise than heart rate:
| Zone | % of FTP | Purpose |
|---|---|---|
| 1 | < 55% | Recovery |
| 2 | 56-75% | Endurance |
| 3 | 76-90% | Tempo |
| 4 | 91-105% | Threshold |
| 5 | 106-120% | VO2 Max |
| 6 | 121-150% | Anaerobic |
Use our Training Zone Calculator.
TSS Tracking
Power enables Training Stress Score calculation:
TSS = (Duration × NP × IF) / (FTP × 3600) × 100
Use our TSS Calculator.
Racing with Power
Pacing
| Race Type | Power Strategy |
|---|---|
| Time trial | Hold steady power (e.g., 95% FTP) |
| Road race | Monitor TSS, save for key moments |
| Hill climb | Pace to specific W/kg target |
| Criterium | Watch normalized power |
Read: Cycling Pacing Strategy.
Post-Race Analysis
Power data reveals:
- Match burning (hard efforts)
- Pacing execution
- Normalized power vs average
- Comparison to training
Choosing a Power Meter
Decision Factors
| Factor | Consider |
|---|---|
| Budget | $300-$1500 range |
| Bikes | Multiple bikes = pedals best |
| Accuracy needs | Racing = higher accuracy |
| Existing setup | What fits current bike |
| Dual-sided? | Nice but not essential |
Budget Options
| Price Range | Options |
|---|---|
| $300-500 | Single-sided crank, budget pedals |
| $500-800 | Quality single-sided, entry dual |
| $800-1200 | Good dual-sided options |
| $1200+ | Premium spider, top pedals |
Common Questions
Is a power meter worth it?
For serious training, yes. Power meters:
- Enable precise training
- Improve pacing
- Track progress objectively
- Increase training efficiency
Which type is best?
No single best type. Consider:
- Pedals for easy swap between bikes
- Crank for permanent installation
- Spider for maximum accuracy
How long do power meters last?
Typically 5-10+ years with proper care. Battery replacement is the main maintenance (every few months to 1 year depending on type).
Do pros use power meters?
Almost universally. Professional cycling relies heavily on power data for training, pacing, and race strategy.