Fixed Gear Ratio Calculator PRO

Popular Drivetrains

Common Wheel Sizes (Dia In)

Chainring

Rear Cog

Wheel Dia (In)

Cadence (RPM)

Crank Length (mm)

Ratio	–
Skid Patches –	–
Gear Inches –	–
Gain Ratio –	–
Speed (MPH / KMH)	– / –

Cadence Reference (MPH / KMH)

Type	RPM	Speed Results
Recovery	70	–
Efficient Cruise	90	–
Sprinting	120	–
Downhill/Emergency	140	–

Saved in Memory

Setup	Ratio	Skid	MPH / KMH

Here is our fixed gear ratio calculator PRO! It calculates the fundamental relationship between your chainring and cog.

The Fixed Gear Mastery Panel

Everything you need to know about drivetrain physics and urban survival.

Mechanical Physics

Development vs. Gear Inches

While “Gear Inches” tells you how hard a gear is, Meters Development tells you how far the bike travels in one pedal stroke. On a fixed gear, this defines your acceleration profile. Physics Fact

Pro Tip: Track racers favor “Development” to calculate exact distance for final sprints.

Maintenance

The 42mm Chainline Standard

Most track hubs use a 42mm chainline. If your front chainring is spaced at 45mm (common for converted road cranks), your chain will run at an angle, causing noise, friction, and dangerous chain drops.

Check: Measure from the center of your frame to the center of your chainring.

Urban Survival

Skip-Stops vs. Hard Skids

Hard skids (locked legs) destroy tires. Skip-stops (briefly locking and “hopping” the rear wheel) are more efficient for slowing down quickly without burning through rubber. Technique

Pro Tip: Unweight your rear wheel by leaning toward the bars to make skip-stopping easier.

Biomechanics

The “Dead Spot” Phenomenon

On a freewheel bike, the “dead spot” (pedals at 12 and 6 o’clock) is where you lose power. On a fixed gear, the kinetic inertia of the drivetrain carries your legs through the dead spot, allowing for a smoother, more circular stroke.

This is why fixed gear riding is excellent for “souplesse” (pedaling efficiency).

Hardware

Lockring Safety & Reverse Threading

Fixed gear cogs thread on clockwise, but lockrings thread on counter-clockwise. This prevents the cog from unscrewing when you back-pedal or skid. Never ride brakeless without a high-quality steel lockring. Critical Safety

Warning: Aluminum lockrings can strip under heavy skidding pressure. Use steel.

Advanced Gearing

The Even-Odd Harmony

Pairing an even chainring (e.g., 48T) with an odd cog (e.g., 17T) is the “golden rule.” It almost always maximizes skid patches and prevents your chain from wearing out in the same spot every time.

Math: This creates a higher Least Common Multiple (LCM) for tooth-link contact.

Mechanical Mastery

Engineering

The 42mm Chainline Standard

Most track hubs use a 42mm chainline. Alignment is critical; a 3mm deviation increases friction by 15% and leads to premature wear.

🔧 Setup

Check: Measure from the frame center to the ring.

Metallurgy

Lockring Safety Standards

Cogs thread clockwise, but lockrings thread counter-clockwise. This “opposing thread” system is the only thing keeping your cog attached during back-pedaling.

⚠️ Critical Safety

Aluminum lockrings can strip under load; steel is mandatory for street.

Urban Survival & Technique

Dynamics

The Gyroscopic Effect

At speed, the heavy rotating drivetrain acts as a stabilizing flywheel. This makes track bikes more stable at high velocity than coasting road bikes.

🔄 Physics

Higher rotational mass makes “no-hands” riding feel more secure.

Performance

Meters Development

Beyond Gear Inches, Development measures exactly how many meters you travel per revolution ($Ratio \times Circumference$).

📊 Metrics

Pros use this to calculate “jump” distance in sprints.

Geometry Deep Dive

Geometry

Bottom Bracket Drop

Track frames feature a High BB (less drop). This provides the necessary ground clearance to keep pedaling through 45-degree banked turns.

📐 Design

Street riders benefit from this via reduced “pedal strike” in turns.

Quality Control

The NJS Certification

NJS parts are built for Japanese Keirin racing. Every component must be identical in strength to ensure races are won by legs, not gear.

💎 Quality

NJS parts are prized for durability and tight tolerances.

fixed gear ratio chart

Here’s a clean fixed-gear ratio chart showing common chainring and cog combinations. Ratios tell you how many wheel revolutions you get per pedal revolution.

Chainring → / Cog ↓	13T	14T	15T	16T	17T	18T
44T	3.38	3.14	2.93	2.75	2.59	2.44
46T	3.54	3.29	3.07	2.88	2.71	2.56
48T	3.69	3.43	3.20	3.00	2.82	2.67
50T	3.85	3.57	3.33	3.13	2.94	2.78
52T	4.00	3.71	3.47	3.25	3.06	2.89