Bicycle Gear Ratio Calculation and Gear Selection: Complete Comparison for Climbing and Flat Roads—How Many T Should You Use?
Equipment Review
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Gear Ratio Determines Your Riding Style
Gear ratio is the number of chainring teeth divided by the number of cassette teeth. It determines how many times the rear wheel rotates for every full pedal revolution.
Chainring Options
| Specification | Name | Best For |
|---|---|---|
| 53/39 | Standard | Professional racing, strong flat-road riders |
| 52/36 | Semi-compact | The top choice for most road cyclists |
| 50/34 | Compact | Lots of climbing, average fitness |
| 48/31 | Super-compact | Extreme climbing (e.g., Wuling) |
| 1x (single ring) | 40-44T | Gravel, simplified operation |
Cassette Options
| Specification | Features |
|---|---|
| 11-25 | Small gear steps, smooth shifting, mainly for flat roads |
| 11-28 | The most common “all-rounder” setup |
| 11-30 | Decent climbing capability |
| 11-32 | Climbing-friendly |
| 11-34 | Suitable for steep slopes or weaker riders |
| 10-36 (12-speed) | Ultra-wide gear range |
Gear Ratio Recommendations for Taiwan Routes
| Route | Recommended Chainring | Recommended Cassette |
|---|---|---|
| Riverside bike paths | 52/36 or 50/34 | 11-28 |
| Yangmingshan (Fengguizui) | 50/34 | 11-30 or 11-32 |
| Wuling | 50/34 or 48/31 | 11-34 |
| Island circumnavigation | 50/34 | 11-32 |
| Racing (criterium) | 52/36 | 11-25 or 11-28 |
Gear Ratio Calculation
Formula: Gear ratio = Chainring teeth ÷ Cassette teeth
| Chainring | Cassette | Gear Ratio | Feel |
|---|---|---|---|
| 50 | 34 | 1.47 | Very light, suitable for steep climbs |
| 50 | 17 | 2.94 | Moderate, cruising on flats |
| 36 | 28 | 1.29 | Lightest gear, a lifesaver on climbs |
| 53 | 11 | 4.82 | Heaviest gear, downhill sprinting |
The Importance of Cadence
Gear ratio selection should account for your preferred cadence:
| Cadence | Type | Gear Ratio Preference |
|---|---|---|
| 60-75 rpm | Power rider | Prefer heavier gears |
| 80-95 rpm | Balanced | Mid-range gears |
| 95-110 rpm | High-cadence spinner | Prefer lighter gears |
Cost of Changing Gear Ratios
| Item | Price Range |
|---|---|
| Cassette replacement | NT$1,500-8,000 |
| Chainring replacement | NT$2,000-10,000 |
| New chain (usually required) | NT$500-2,000 |
| Rear derailleur (if gear range exceeds capacity) | NT$2,000-15,000 |
Before changing gear ratios, make sure your rear derailleur can handle the new gear range. Short-cage (SS) and long-cage (GS) rear derailleurs have different maximum cassette tooth capacities.
Choosing the right gear ratio won’t make you stronger, but it will let you perform at your true level in the right way.