A bike that fits is faster, more comfortable and safer. Enter your height and inseam to find the right frame size for a road, gravel, mountain or hybrid bike, plus a starting saddle height.
Table of Contents
How to measure your inseam
- Stand barefoot with your back against a wall, feet about 6 inches apart.
- Slide a hardcover book up between your legs until it is snug, like a saddle.
- Measure from the floor to the top of the book. Repeat twice and use the average.
Frame size formulas
- Road bike frame (cm) = inseam (cm) × 0.665
- Mountain bike frame (in) = inseam (cm) × 0.226
- Hybrid bike frame (in) = inseam (cm) × 0.685 ÷ 2.54
- Saddle height (bottom bracket to top of saddle) ≈ inseam × 0.883
Frequently asked questions
What size bike for a 5′10″ person?
Most riders who are 5′10″ fit a 54–56 cm road bike or a medium (17–18″) mountain bike.
Should I size up or down between sizes?
Size down for a more agile, sporty feel; size up for a stretched-out, stable ride. Your reach and flexibility matter too.
Are all brands sized the same?
No. Always compare with the manufacturer’s size chart, and look at stack and reach if you can.