Calculate your saddle height and the size of your next bike!

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Bike Size Calculator

Rider height: 175 cm

Inseam length (barefoot): 82 cm

Riding position preference

Intended stem length (optional): 100 mm

Why use this calculator to determine your saddle height and choose your bike size?

Unsure about your road or gravel bike size, or want to quickly calculate your saddle height? Enter your height, inseam, and preferred position (comfort, balanced, sporty). The calculator returns:

a recommended size,
a saddle height with a ±0.5 cm range (to account for bib shorts, pedals, etc.),
stack, reach and ETT (effective top tube) references,
a target cockpit (ETT + stem) to better compare between two sizes.

Goal: a simple, realistic choice. Sizes vary by brand – stack and reach remain the best reference points to determine your bike size and position.

How to use the calculator (road & gravel)

Enter your height (in cm).
Measure your inseam barefoot (see method below) and enter the value.
Choose your style: Comfort / Balanced / Sporty.
(Optional) Enter the stem length you have in mind.
Click Calculate to get: bike size, saddle height, stack, reach, ETT and cockpit.

Calculate saddle height: the simple (and accurate) method

To calculate saddle height, we start from a modern inseam-based ratio: Saddle height ≈ 0.875 × inseam (bottom bracket axis → top of saddle), with a ±0.5 cm tolerance.

The ±0.5 cm window covers:

the thickness of bib shorts and padding,
cleat/pedal stack and crank length,
saddle shape (flat vs. curved) and pedaling style.

Do a real-world test: if you rock your hips or feel a pressure point, lower by 2-3 mm; if you feel compressed and lack extension, raise by 2-3 mm.

How to measure your inseam correctly

Barefoot, back against a wall, legs slightly apart (5-10 cm).
Place a book (spine up) firmly between your legs to simulate the saddle.
Measure from the floor to the top edge of the book: this is your inseam.

Choose your bike size: understand stack, reach & ETT

To choose the right bike size (road or gravel), focus on comparing:

Stack: vertical height of the front end relative to the bottom bracket. The higher the stack, the more upright the position (comfort).
Reach: horizontal distance between the bottom bracket and the top of the head tube. The larger the reach, the more stretched-out the position (sporty).
ETT (effective top tube): top tube length measured horizontally. It is a good marker for comparing frame length across brands.
Top tube length + stem: the perceived length once the stem is chosen. Very useful when you are between two sizes.

Tip: if you are between two sizes, choose the one whose stack/reach best matches your riding. Endurance = slightly higher stack. Sport = slightly longer reach.

🔔 This calculator provides indicative markers for your bike (road or gravel): geometries vary by brand and fine-tuning depends on your equipment and preferences. For an optimized position (comfort, performance, pain prevention), have it validated by a professional bike fitting and then fine-tune on the road in small increments.

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