Ratio Fixie Calculator
Instantly compute gear ratio, development and speed for your fixed‑gear bike.
Calculate Your Fixed‑Gear Setup
Number of teeth on the front chainring.
Number of teeth on the rear cog.
Effective wheel diameter in millimetres.
Pedal revolutions per minute.
| Gear Ratio | Development (mm) | Speed at 90 RPM (km/h) |
|---|
What is {primary_keyword}?
The {primary_keyword} is a specialized tool for cyclists who ride fixed‑gear (fixie) bicycles. It calculates the gear ratio, development per pedal revolution, and the resulting speed based on your chosen chainring, cog, wheel size, and cadence. Anyone who wants to fine‑tune their fixie for optimal performance—whether a commuter, racer, or hobbyist—can benefit from a {primary_keyword}. Common misconceptions include thinking that a larger chainring always means higher speed; the {primary_keyword} shows that wheel diameter and cadence also play crucial roles.
{primary_keyword} Formula and Mathematical Explanation
The core formula used by the {primary_keyword} is straightforward:
Gear Ratio = Chainring Teeth ÷ Cog Teeth
Development (mm) = Gear Ratio × π × Wheel Diameter
Speed (km/h) = Development × Cadence ÷ 1,000,000 × 60
These equations convert the mechanical setup of a fixie into real‑world speed. Below is a table of variables used by the {primary_keyword}:
| Variable | Meaning | Unit | Typical Range |
|---|---|---|---|
| Chainring Teeth | Number of teeth on front chainring | teeth | 38‑53 |
| Cog Teeth | Number of teeth on rear cog | teeth | 13‑20 |
| Wheel Diameter | Effective diameter of the wheel | mm | 600‑800 |
| Cadence | Pedal revolutions per minute | rpm | 60‑120 |
Practical Examples (Real‑World Use Cases)
Example 1: Urban Commuter
Inputs: Chainring = 48 teeth, Cog = 16 teeth, Wheel = 700 mm, Cadence = 90 rpm.
Using the {primary_keyword}, the gear ratio is 3.00, development is 6,597 mm, and speed is 35.5 km/h. This shows a commuter can maintain a brisk pace without excessive effort.
Example 2: Track Racer
Inputs: Chainring = 50 teeth, Cog = 15 teeth, Wheel = 660 mm, Cadence = 110 rpm.
The {primary_keyword} yields a gear ratio of 3.33, development of 6,904 mm, and speed of 45.2 km/h, ideal for high‑speed track events.
How to Use This {primary_keyword} Calculator
- Enter your chainring and cog tooth counts.
- Specify the wheel diameter in millimetres.
- Set your typical cadence (rpm).
- The {primary_keyword} updates instantly, showing gear ratio, development, and speed.
- Read the primary result (speed) highlighted in green.
- Use the table for a quick reference of intermediate values.
- Consult the dynamic chart to see how speed varies with cadence.
- Copy the results for sharing or record‑keeping.
Key Factors That Affect {primary_keyword} Results
- Chainring Size: Larger chainrings increase gear ratio, boosting speed.
- Cog Size: Smaller cogs raise the gear ratio, also raising speed.
- Wheel Diameter: Bigger wheels increase development per pedal turn.
- Cadence: Higher cadence directly raises speed in the {primary_keyword}.
- Tire Width: Wider tires slightly increase effective diameter, affecting the {primary_keyword} outcome.
- Rider Power Output: While not a direct input, the {primary_keyword} assumes the rider can sustain the chosen cadence.
Frequently Asked Questions (FAQ)
- Can I use the {primary_keyword} for multi‑speed bikes?
- No, the {primary_keyword} is designed specifically for single‑speed fixed‑gear setups.
- What if my wheel size is in inches?
- Convert inches to millimetres (1 in = 25.4 mm) before entering the value into the {primary_keyword}.
- Does the {primary_keyword} account for gear slip?
- Gear slip is negligible on a properly maintained fixie, so the {primary_keyword} assumes ideal conditions.
- How accurate is the speed calculation?
- The {primary_keyword} provides a theoretical speed; real‑world factors like wind and rolling resistance may cause slight variations.
- Can I change the cadence range on the chart?
- Currently the chart displays 60‑120 rpm; you can modify the JavaScript to adjust the range.
- Is the {primary_keyword} mobile‑friendly?
- Yes, the table scrolls horizontally and the chart resizes to fit any screen.
- Do I need to reset the calculator after each use?
- No, the {primary_keyword} updates in real time, but you can use the Reset button to start fresh.
- Can I copy the results for a spreadsheet?
- Use the Copy Results button; the {primary_keyword} copies all key values in a tab‑separated format.
Related Tools and Internal Resources
- {related_keywords} – Detailed guide on selecting chainring sizes.
- {related_keywords} – Wheel diameter calculator for various bike types.
- {related_keywords} – Cadence training planner for fixie riders.
- {related_keywords} – Fixed‑gear maintenance checklist.
- {related_keywords} – Comparison of popular fixie setups.
- {related_keywords} – Community forum for fixie enthusiasts.