What is bike development (rollout)?

Development, or rollout, is the distance your bike travels in one full pedal revolution, usually shown in meters. It is calculated as (front teeth ÷ rear teeth) × wheel circumference. It is commonly used in track cycling and youth gear restrictions.

How do I choose the right bike gears?

Choose gears based on terrain, fitness, and cadence. For hilly routes or lower fitness, prioritize lower gears (small chainrings and big cogs). For flat routes and racing, you can use higher gears. Aim to keep your preferred cadence (e.g., 80–95 rpm) in the middle of the cassette for most of your riding.

What cadence should I use on the bike?

Most riders are efficient between 75 and 95 rpm on the road. Sprinters may exceed 110 rpm, while beginners might feel comfortable closer to 70 rpm. Use the calculator to see what speed each gear gives you at your preferred cadence, then adjust gearing to avoid excessive spinning or grinding.

Does wheel size affect bike gearing?

Yes. For the same chainring and cassette, a larger wheel travels further per pedal stroke, giving higher gear inches and speed. That is why 29" MTB wheels feel "harder" than 26" with identical drivetrain components. Always set the correct wheel size and tyre width in the calculator.

Bike Gear Calculator

Q: What is bike gear inches?

Gear inches express how far your bike would travel in one crank revolution if the wheel were one inch in diameter. It is calculated as (front teeth ÷ rear teeth) × wheel diameter in inches. Higher gear inches mean a harder gear that goes faster at the same cadence.

Compare bike gears, gear inches, development (rollout) and speed for any chainring, cassette and wheel size. Ideal for road, MTB, gravel and e-bikes.

Interactive Bike Gear Calculator

Bike & Drivetrain Step 1

Preset

Wheel size

Custom wheel diameter (mm)

Only used if wheel size is set to “Custom”.

Chainrings (front teeth)

Comma-separated, e.g. 50,34 for 2×, or 40 for 1×.

Cassette / cogs (rear teeth)

Smallest to largest, e.g. 11,12,13,14,16,18,21,24,28.

Cadence & Speed Step 2

Cadence (rpm)

Extra cadence rows

Speed unit

Development unit

Tip: Use presets, then fine-tune chainrings or cassette to simulate upgrades (e.g., going from 11–28 to 11–34).

Gear table

Ring	Cog	Ratio	Gear inches	Rollout	Speed @ main cadence
Set your drivetrain and click “Calculate gear table”.

Hover a row to highlight; rows are sorted from easiest (lowest ratio) to hardest (highest ratio).

How the bike gear calculator works

This bike gear calculator lets you explore how different chainrings, cassettes and wheel sizes affect:

Gear ratio – how many wheel turns per crank revolution
Gear inches – classic measure of gear “hardness”
Development / rollout – distance travelled per pedal stroke
Speed at your chosen cadence (rpm)

Formulas used

1. Gear ratio

\[ \text{Gear ratio} = \frac{T_\text{front}}{T_\text{rear}} \] where \(T_\text{front}\) is the number of teeth on the chainring and \(T_\text{rear}\) is the number of teeth on the rear cog.

2. Wheel circumference

We approximate the effective wheel diameter from the selected preset or your custom value and compute:

\[ C = \pi \cdot D \] where \(C\) is circumference and \(D\) is wheel diameter (in meters).

3. Development (rollout)

\[ \text{Development} = \text{Gear ratio} \times C \] This is the distance the bike travels in one full pedal revolution.

4. Gear inches

Gear inches are defined as:

\[ \text{Gear inches} = \text{Gear ratio} \times D_\text{inches} \] where \(D_\text{inches}\) is the effective wheel diameter in inches.

5. Speed at a given cadence

Cadence is the number of crank revolutions per minute (rpm). Speed is:

\[ v_\text{m/s} = \text{Development} \times \frac{\text{cadence}}{60} \] \[ v_\text{km/h} = v_\text{m/s} \times 3.6 \] \[ v_\text{mph} = v_\text{m/s} \times 2.23694 \]

Choosing bike gears for different riding styles

Road cycling

Modern road bikes often use 2× drivetrains such as 50/34 or 52/36 with an 11–28 or 11–32 cassette. As a rough guide:

Climbing: aim for a lowest gear around 30–35 gear inches if you ride steep hills regularly.
Flat cruising: a mid gear around 70–85 gear inches at 80–95 rpm gives 25–35 km/h (15–22 mph).
Sprinting: top gears above 110 gear inches allow 60+ km/h (37+ mph) at high cadence.

Gravel and bikepacking

Gravel bikes benefit from lower gears, especially when loaded with bags. Try:

Smallest gear below 25–30 gear inches for steep, loose climbs.
Use the calculator to compare 46/30 vs 48/31 or 1× setups like 40 with 10–50.

Mountain biking (MTB)

With 1× drivetrains (e.g., 32 with 10–51), MTBs rely on wide-range cassettes. For technical trails:

Target a lowest gear around 18–24 gear inches for slow, controlled climbing.
Check that your top gear still gives enough speed on fire roads or tarmac transitions.

Practical tips when using the calculator

Match your cadence: set your preferred cadence (e.g., 85–90 rpm) and see which gears cover your typical speeds.
Avoid big jumps: look for even spacing in development between gears to keep cadence changes small when shifting.
Simulate upgrades: change only the cassette or chainring values to see how a new component will feel before buying.
Check youth / track limits: use development (meters) to verify you meet gear rollout restrictions for competitions.

Bike gear calculator FAQ

What is bike gear inches?

Gear inches are a traditional way to describe how “hard” or “easy” a gear is. It is the diameter of an equivalent high-wheel (penny-farthing) bicycle wheel that would travel the same distance per pedal revolution. Higher gear inches mean more distance per stroke and therefore higher speed at the same cadence, but also more force required.

What is development (rollout) and why does it matter?

Development (or rollout) is the distance your bike travels with one full crank revolution. It is especially important in:

Track cycling – where gear rollout is strictly controlled.
Youth racing – where maximum rollout limits are used instead of gear tooth counts.
Bike fitting & pacing – to understand how far you move per pedal stroke at a given cadence.

How accurate is the speed calculation?

The calculator uses standard tyre size approximations for each wheel preset. Real-world speed can differ slightly due to tyre brand, pressure, rider weight and surface. For best accuracy, measure one full wheel revolution on the ground and enter the equivalent diameter in millimetres as a custom value.

Can I use this for e-bikes?

Yes. E-bikes use the same mechanical gearing as conventional bikes. This tool helps you see which gears keep you near the motor’s optimal cadence and within legal speed limits in your region. Just select the correct wheel size and your drivetrain.

How do I export or share my gear table?

Click “Download CSV” to export the current table. You can open the file in Excel, Google Sheets or any spreadsheet tool to compare multiple bikes, plot graphs, or share with your coach or bike fitter.