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Bike Gear Speed Calculator

Easily calculate your bike speed by gear ratio, cadence, and wheel size with our free Bike Gear Speed Calculator. Perfect for MTB, road, and hybrid bikes.

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Are you curious to know how fast you’re going based on your current bike gear? Our Bike Gear Speed Calculator is designed to make it easy for cyclists of all types mountain bikers, road cyclists, and commuters to calculate their speed using simple gear settings and cadence.

Whether you're riding a Shimano gear system, an 18-speed mountain bike, or a fixed gear setup, knowing your speed can help you train smarter, improve performance, or just understand your ride better.

With our tool, you can instantly calculate your bike’s speed based on your pedal cadence (RPM), chainring size, cog size, and wheel diameter.

How Bike Gear and Speed Work

The speed of a bicycle depends on several key factors:

  • The size of the chainring (front gear)
  • The size of the rear cog
  • Your cadence (pedal revolutions per minute)
  • The wheel size (diameter including the tire)

When you change gears, you're adjusting the gear ratio, which determines how far your bike moves with each pedal stroke. A higher gear (larger front ring or smaller rear cog) results in greater speed, but it also requires more effort.

How to Use the Bike Gear Speed Calculator

Using our bike gear speed calculator is very simple. Just follow these steps:

  1. Enter your cadence (RPM): This is how many times you pedal in one minute. Common values range from 60 to 100 RPM.
  2. Enter the number of teeth on your front chainring. Example: 50 teeth.
  3. Enter the number of teeth on your rear cog. Example: 12 teeth.
  4. Enter your wheel diameter. This includes the tire. For a 700x25c road bike tire, use 27 inches. For a 29" MTB, use around 29 inches.

Once you input these values, the calculator will show you your bike speed in kilometers or miles per hour.

Gear Speed Calculation Formula

To understand how the calculator works, here's the simple formula it uses:

Gear Ratio = Chainring Teeth ÷ Cog Teeth

Distance per Pedal Revolution = Gear Ratio × Wheel Circumference

Speed = (Distance per Revolution × RPM × 60) ÷ 1000 (for km/h)

Example:

  • Chainring: 50 teeth
  • Cog: 12 teeth
  • RPM: 90
  • Wheel Diameter: 27 inches (circumference ≈ 2.13 meters)

Gear Ratio = 50 / 12 = 4.17

Distance per Revolution = 4.17 × 2.13 = 8.88 meters

Speed = (8.88 × 90 × 60) ÷ 1000 = 47.9 km/h

So, at 90 RPM with a 50/12 gear on a 27-inch wheel, you’re riding at approximately 47.9 km/h.

What Is the Speed of a Bike According to Gear?

Gear ratio directly affects speed. A higher gear ratio means more distance covered per pedal stroke, translating into higher speed if you can maintain the cadence. On flat roads, higher gears work well for speed. On hills, lower gears help with climbing.

For example, a Shimano 18-speed bike lets you fine-tune your gear ratio to match your terrain and cadence, giving you more control over your speed and efficiency.

What Speed is 90 RPM on a Bike?

Speed at 90 RPM depends on your gear setup and wheel size. In general, 90 RPM with a 50-tooth chainring and 12-tooth cog on a 700c wheel results in about 47–50 km/h.

What Speed is 100 RPM on a Bike?

Using the same 50/12 setup at 100 RPM, your speed would increase to approximately 53–56 km/h, depending on your exact tire size.

What Are 18 Speed Gears on a Bike?

An 18-speed bike has 3 front chainrings and 6 rear cogs (3 × 6 = 18 gear combinations). It gives you a wide range of gear ratios to choose from, which is ideal for adapting to different terrains and cycling styles.

Final Verdict

The Bike Gear Speed Calculator is a must-have tool for cyclists who want to understand their performance, train more efficiently, or just geek out about their bike setup. It simplifies complex gear mechanics into an easy-to-use tool, whether you're riding an MTB, road bike, or using a Shimano gear system.

Whether you're wondering how fast 90 RPM takes you, what gear ratio suits your ride, or how your mountain bike compares to others, our calculator is designed to give you accurate results fast.

FAQs

What is a good cadence for cycling?

A good cadence is between 80–100 RPM for most riders. Beginners may find lower RPMs more comfortable.

Can I use this calculator for mountain bikes?

Yes! This calculator works perfectly for mountain bikes, road bikes, hybrids, and even motorcycles with manual transmission ratios.

Does wheel size matter?

Absolutely. Larger wheels cover more distance per revolution, which means higher speed at the same cadence and gear ratio.

Is this calculator accurate for Shimano gears?

Yes. Shimano gears are just another gear system what matters are the number of teeth and cadence, which the calculator uses.

Can I calculate bike speed using watts?

This calculator doesn’t measure watts directly, but speed indirectly reflects power output. You can use a bike speed calculator watts tool separately for that.