📏 Bike Size Calculator
Quickly determine recommended frame sizes based on your body dimensions and riding style.
Recommended Frame
54–56 cm
Based on height range for road bikes
Seat Tube Estimate
55 cm
Adjust with saddle height calculator for precision
Top Tube Estimate
70.0 cm
Use reach & stack for high-performance bike fits.
Standover Clearance
Aim for ~72.6 cm standover height (inseam × 0.885) when choosing frame geometry.
How to Use This Calculator
Measure accurately
Record height without shoes and inseam using a book pressed to your crotch.
Select bike style
Choose road, mountain, or hybrid to align with geometry differences.
View recommendations
The tool shows frame size ranges and key fit metrics.
Refine with test rides
Use this as a starting point, then fine-tune reach, stem, and saddle height.
Formula
Road Frame Size ≈ Inseam × 0.67 • Mountain Frame (in) ≈ Inseam × 0.226
Classic bike-fit formulas combine inseam-based seat tube estimates with height-based sizing charts. Use manufacturer geometry charts to find stack and reach once you identify your frame category.
Example
175 cm rider, 82 cm inseam → Road frame ≈ 55 cm, mountain frame ≈ 18 in (size L). Height range confirms a 54–56 cm road bike.
Variables
- Inseam: Determines seat tube/standover
- Height: Guides overall frame category
- Bike type: Adjusts geometry assumptions
Understanding Bike Fit
Frame size affects comfort, power transfer, and handling. While charts give a baseline, modern bike fitting also considers flexibility, riding style, and reach preferences.
Fine-Tuning Fit
- Use professional bike fitting to dial in saddle height, setback, and cockpit length.
- Swap stems or handlebars to customize reach after choosing the frame.
- Women-specific frames often feature shorter top tubes—evaluate reach comfort.
Hybrid Bikes
Hybrids combine road and MTB traits. Size recommendations split between centimetre (road-style) and inch (MTB-style) measurements; test rides help confirm preference.
Frequently Asked Questions
How precise is this sizing?
Use it as a starting point. A full fit accounts for torso length, flexibility, and riding goals.
Should I size up or down between categories?
Race riders often size down for aggressiveness; endurance riders prefer slightly taller frames for comfort.
Do women need different sizing?
Not necessarily, but women-specific frames adjust reach and stack. Compare geometry charts to your proportions.
Can inseam measurements vary?
Yes—measure multiple times wearing bike shorts for accuracy. Use a level book for consistent readings.
What about kids bikes?
Kids’ sizing relies on wheel diameter (e.g., 20 in, 24 in). This calculator is designed for adult bikes.