What size bike do I need?

The right frame size depends mainly on your inseam – not just your height. Two people of the same height can need different frame sizes because of different leg and torso proportions. That's why we ask for both.

How to measure your inseam

Stand barefoot with your back against a wall, feet about hip-width apart. Pull a book firmly up between your legs, the way a saddle would sit. Then measure from the floor to the top edge of the book – that's your inseam.

Road, gravel and cyclocross sizing

Road bikes, gravel bikes and cyclocross bikes are usually sized in centimeters (e.g. 54 or 56 cm) and share a similar geometry with drop bars and a more stretched position than hybrids. Our calculator uses its own inseam factor for them.

Mountain bike sizing

Mountain bike frames were traditionally sized in inches (e.g. 17" or 19"); most brands now use S/M/L/XL. The riding position is usually more upright than on a road bike, so the factor differs as well.

Hybrid, city and e-bike sizing

Hybrid, trekking and city bikes are designed for a comfortable, upright position – with the same inseam, the frame size tends to be larger than on a road bike.

What are stack and reach?

Stack is the vertical distance from the bottom bracket to the top of the head tube; reach is the horizontal distance between the two. Both allow you to compare frames across brands regardless of the size label – two frames labeled "54 cm" from different brands can differ noticeably in stack and reach.

Between two sizes

If you fall between two sizes, both are usually rideable – choose based on your preferred position. The smaller size tends to feel more agile and compact, the larger one more stretched and stable at speed.

FAQ

Does the calculator replace a professional bike fit?
No. It gives you a solid starting point based on your measurements, not an individual biomechanical fitting. Many local bike shops offer professional fits – find one near you.

Why isn't my height enough?
Two people of the same height can have different leg lengths – which affects the right frame size more than height alone.

What if two sizes fit equally well?
Then we honestly show you both options with a short assessment instead of pretending to be more precise than we are.