Caleb MorganBy Caleb Morgan

Updated November 2026

A bike size chart in centimeters matches your height to a frame size you can compare across brands. Most adult frames are listed in cm, measured along the seat tube, so once you know your height and inseam, you can narrow your options in a few minutes. This guide walks through how to read the chart, take the two measurements that matter, and check the fit before you commit.

Step 1: Measure Your Height and Inseam

Start with two numbers. Height is simple: stand barefoot against a wall, flat-footed, and mark the top of your head. Measure from the floor to the mark in centimeters. Inseam is the distance from the crotch to the floor. Stand against a wall with a hardcover book between your legs, spine snug against the book, and measure from the book’s top edge to the floor. Multiply the inseam by 0.67 for a rough road-bike reference, or use it as a cross-check on your height-based size.

Shopping for one? See our guide: 5 Best Road Bike Shoe Size Charts (2026): Expert Picks.

Step 2: Read the Size Chart by Height

Most brands publish a height-based chart that looks roughly like this. Treat it as a starting point, because each manufacturer draws its own lines.

Rider height (cm) Typical frame size (cm)
150–160 44–47
160–168 47–50
168–175 50–53
175–182 53–56
182–190 56–59
190+ 59–62

If you fall between two sizes, look at your inseam and your arm length. Riders with long legs relative to their torso often do better on the larger size, while riders with long torsos may prefer the smaller frame with a longer stem.

Step 3: Check the Fit on the Bike

A chart gets you close, but the fit confirms it. Use these checks before you buy or adjust:

  • Stand over the top tube with both feet flat. You should have roughly 2 to 5 cm of clearance on a road or hybrid bike, and more on a mountain bike.
  • Sit on the saddle with the pedal at the bottom of its stroke. Your knee should have a slight bend, around 25 to 35 degrees.
  • Reach to the handlebars. Your back should be relaxed rather than stretched, and your hands should rest without strain.
  • Look at the seat tube length and top tube length, not just the size label, since two brands can label the same height differently.

Step 4: Adjust Within Your Size

Once you have a size, small changes do a lot. Raising or lowering the saddle by even 1 cm changes knee angle noticeably. A shorter or longer stem shifts your reach, and a different saddle position moves your weight over the pedals. Make one change at a time and ride at least 20 minutes before judging it.

Tools that help

  1. A flexible tape measure for height and inseam
  2. A hardcover book for the inseam measurement
  3. A wall and a level surface for standing measurements
  4. A notebook to record your numbers and the chart you used

Common mistakes

  • Trusting the size label alone. Compare the seat tube and top tube lengths between brands.
  • Measuring height in shoes. Heels or thick soles inflate the number.
  • Ignoring inseam. Short legs on a long frame make the reach too far.
  • Buying a bike that barely fits and planning to adjust later. Adjustments can only go so far.

A basic cloth tape measure makes the height and inseam checks easier to repeat accurately. View on Amazon

A sturdy hardcover book is all you need for the inseam measurement, and it stays flat against the wall. View on Amazon

FAQ

Is a bike size chart in cm accurate for every brand?

It gives a reliable starting point, but each manufacturer sets its own ranges. Always confirm with the brand’s geometry chart before buying.

Should I size by height or inseam?

Use both. Height gives the general size, and inseam helps you decide between two sizes. A fitting professional can give a more precise answer if you’re unsure.

How do I know if a frame is too big?

If you cannot stand over the top tube with flat feet or you stretch too far to reach the bars, the frame is likely too large. Consider a smaller size or a shorter stem.

Conclusion

Measure your height and inseam, match them to a size chart in centimeters, and then confirm the fit with a few on-bike checks. Use the chart to narrow your choices, not to make the final decision. If an injury or a long-term riding issue is a concern, talk with a qualified bike fitter.

Ready to choose one?

Caleb Morgan

About Caleb Morgan

Caleb Morgan is part of our editorial team and reviews and edits our cycling for beginners guides, checking product details against manufacturer specifications and owner feedback.