Gear Ratio vs Gear Inches: The Complete Guide for Single Speed Bikes
When you ride a single speed bike, every pedal stroke counts. There’s no shifter, no derailleur—just pure connection between your legs and the road. That’s the beauty of simplicity. But understanding the mechanics behind that simplicity—specifically gear ratio and gear inches—can make all the difference between a smooth, efficient ride and a grind that wears you down.
In this guide, we’ll break down the difference between gear ratio and gear inches, how to calculate both, and how they affect your ride. Whether you’re commuting, climbing, or racing fixed-gear, this post will help you find your ideal gearing setup.
What Is a Gear Ratio?
At its core, gear ratio is a simple concept—it’s the relationship between the number of teeth on your front chainring and the number on your rear cog.
Formula:
Gear Ratio = (Number of Chainring Teeth) ÷ (Number of Cog Teeth)
So, if you have a 32-tooth chainring and a 16-tooth rear cog, your gear ratio is 2.0.
That means:
- For every full turn of your cranks, your rear wheel turns twice.
The higher the gear ratio, the harder it is to pedal—but the faster you’ll go once you’re moving. The lower the ratio, the easier it is to pedal, but you’ll spin out at lower speeds.
How Gear Ratio Feels on the Road
- High Gear Ratio (e.g. 3.0 or above)
Great for speed and flat terrain. You’ll cover more distance per pedal stroke but need more strength to get going. - Medium Gear Ratio (around 2.0–2.5)
A balanced setup that’s common for urban riders or moderate terrain. You get solid acceleration with decent cruising speed. - Low Gear Ratio (below 2.0)
Ideal for climbing hills or cruising casually. Easier to pedal, but you’ll “spin out” quickly at higher speeds.
If you’re building or tuning your single speed bike, this number tells you a lot—but not everything. To understand how it translates into real-world riding feel, we need to bring gear inches into the equation.
What Are Gear Inches?
Gear inches take the gear ratio and multiply it by your wheel diameter to show how far your bike travels with one pedal revolution. It’s a more precise measure of how “tall” or “short” your gearing feels when you ride.
Formula:
Gear Inches = (Wheel Diameter in Inches) × (Gear Ratio)
So if you’re running 27.5-inch wheels and a 2.0 gear ratio:
27.5 × 2.0 = 55 Gear Inches
That means every full turn of the pedals moves your bike forward roughly 55 inches.
Why Gear Inches Matter
Gear inches give a more complete picture of your setup because they factor in wheel size. For example:
- A 32×16 setup on 29” wheels feels slightly taller (harder) than the same setup on 27.5” wheels.
- A rider on 27.5” wheels might have 55 gear inches, while a 29er with the same gearing has closer to 58.
That difference may not seem big—but you’ll feel it on steep climbs or long rides.
Gear Inches = Real-World Effort
To summarize:
- Lower gear inches = easier pedaling, slower top speed.
- Higher gear inches = harder pedaling, faster top speed.
Most single speed mountain bikers stick between 45–65 gear inches, while road riders often go 65–85. Your ideal number depends on terrain, strength, and riding style.
Comparing Gear Ratio and Gear Inches
| Measurement | What It Describes | Variables | Best For |
|---|---|---|---|
| Gear Ratio | Crank-to-wheel rotation ratio | Chainring & cog teeth | Simplicity, easy comparison |
| Gear Inches | Actual wheel travel per crank revolution | Chainring, cog, and wheel size | Real-world performance feel |
Think of gear ratio as the math, and gear inches as the experience.
Gear ratio tells you the relationship between front and rear cogs. Gear inches tell you how that relationship feels under your tires.
Example Gear Ratio Chart
Here’s a quick reference based on common setups for single speed riders:
| Chainring | Cog | Ratio | Gear Inches (27.5″) |
|---|---|---|---|
| 32 | 16 | 2.00 | 55.0 |
| 32 | 18 | 1.78 | 48.9 |
| 34 | 16 | 2.13 | 58.4 |
| 36 | 17 | 2.12 | 58.2 |
| 39 | 18 | 2.17 | 55.0 |
| 33 | 15 | 2.20 | 60.5 |
You can see how a single tooth change in either cog can make a noticeable difference in how the bike rides. More single speed gear ratio chart and gear inches chart here.
Finding Your Perfect Single Speed Gear
When choosing a setup, you’re balancing three key factors:
- Terrain
- Flat = higher gear ratio
- Hilly = lower gear ratio
- Riding Style
- Commuter or urban = 2.0–2.4
- Trail or XC = 1.6–2.1
- Track or road = 2.5–3.0
- Strength and Cadence
- Stronger riders often prefer taller gears (more speed per stroke).
- Spinners (high cadence riders) often favor lower gearing for rhythm and endurance.
A great starting point for most single speed mountain bikers is 32×18 (about 1.78 ratio / 49 gear inches). From there, you can fine-tune by swapping a cog or chainring.
How Endless Bike Co. Helps You Dial It In
At Endless Bike Co., we’ve been building precision-machined single speed cogs in Western North Carolina for riders who appreciate both craftsmanship and performance. Our cogs are made in America, designed to mesh perfectly with your drivetrain and last through countless climbs, descents, and commutes.
Because every tooth counts, our cogs are CNC-cut from premium materials to deliver consistent engagement, minimal wear, and smooth power transfer. Whether you’re dialing in for endurance, technical climbs, or fast-paced flow trails, choosing the right cog size is key to finding your ideal gear ratio and gear inches.
How to Calculate Your Gear Ratio and Gear Inches (Step-by-Step)
Step 1: Count the Teeth
- Find the number stamped or etched on your front chainring and rear cog.
Step 2: Divide for Ratio
- Chainring ÷ Cog = Gear Ratio
Step 3: Multiply by Wheel Size
- Gear Ratio × Wheel Diameter = Gear Inches
Example:
Chainring: 34T
Cog: 18T
Wheel: 29”
34 ÷ 18 = 1.89
1.89 × 29 = 54.8 gear inches
That’s a comfortable middle ground—perfect for mixed terrain.
How Wheel Size Changes the Feel
A common oversight for single speed riders is assuming that a ratio feels the same across bikes. It doesn’t. Here’s why:
- 27.5-inch wheels have smaller circumference → easier start, less distance per pedal.
- 29-inch wheels have larger circumference → harder start, more distance per pedal.
For example:
- 32×18 on 27.5″ = 48.9 gear inches
- 32×18 on 29″ = 51.6 gear inches
That 2.7” difference translates to noticeable resistance when climbing.
Pro Tips for Single Speed Gearing
- Change One Tooth at a Time
A single tooth can make a big difference. If you’re between ratios, swap just the cog or chainring first. - Don’t Forget Chain Tension
When you change gearing, your chain length may need adjusting. Keep proper tension for silent, efficient power transfer. - Mind Your Tires
Bigger-volume tires effectively increase your wheel diameter—slightly raising your gear inches. - Track Your Rides
Try logging cadence and effort using a bike computer. This helps find your personal sweet spot over time. - Invest in Quality Cogs
Precision-made cogs (like those from Endless Bike Co.) ensure consistent engagement and reduce drivetrain wear. It’s one of the best upgrades you can make.
FAQs About Gear Ratio and Gear Inches
1. What is the best gear ratio for a single speed mountain bike?
Most riders prefer between 1.7–2.1. A 32×18 setup is a popular starting point for 27.5” or 29” wheels.
2. What does “gear inches” actually tell me?
Gear inches represent how far your bike moves with one full crank revolution. It helps you compare setups across different wheel sizes.
3. How do I make my single speed easier to pedal?
Use a larger rear cog or smaller front chainring to lower your gear ratio and gear inches.
4. Does tire size affect gear inches?
Yes. Larger tires slightly increase your effective wheel diameter, which raises your gear inches and makes pedaling a bit harder.
5. What’s the advantage of Endless Bike Co. cogs?
Endless Bike Co. cogs are CNC-machined in the USA with exact tolerances, giving riders smoother engagement, better chain retention, and long-lasting performance.
6. How often should I replace a single speed cog?
It depends on use, but a high-quality cog can last several thousand miles if the chain is maintained properly.
It’s Bike Nerd Math
Understanding gear ratio and gear inches unlocks the full potential of your single speed setup. Gear ratio gives you the mechanical relationship between chainring and cog; gear inches translate that into how the bike feels under your legs. Together, they help you fine-tune your ride for terrain, strength, and style.
And when it comes time to adjust your setup, choosing the right cog matters.
With Endless Bike Co.’s American-made single speed cogs, you get precision, performance, and pride—all built in Western North Carolina.
👉 Check out Endless Bike Co. Single Speed Cogs
Ride simple. Ride strong. Ride Endless.