Caleb MorganBy Caleb Morgan

Updated November 2026

An REI bike size chart tells you which frame size to start with based on your height and inseam, and it is the fastest way to narrow down your options. This guide shows you how to read the chart, measure yourself correctly, and confirm the fit before you commit to a purchase. Most beginners can settle on a likely size in under ten minutes.

How to Read the REI Bike Size Chart

REI groups its bikes by frame size, usually labeled XS, S, M, L and XL, though some models list numeric sizes in inches or centimeters instead. Each size is paired with a height range, and many charts also list a recommended inseam range. Start with height, then check inseam, because the two measurements together give a more reliable answer than either one alone. If your numbers fall between two sizes, the inseam usually decides it.

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

Measure Your Height and Inseam Correctly

Accurate measurements make the chart useful. Take both measurements barefoot, standing against a wall with your heels together.

  1. Height: stand straight with your back against the wall, look straight ahead, and mark the top of your head. Measure from the floor to the mark.
  2. Inseam: stand with your feet about six inches apart and place a hardcover book between your legs, spine up, pressed firmly against your crotch. Mark the top of the book on the wall and measure from the floor to the mark.
  3. Record both numbers in inches and centimeters so you can match the chart’s units.

Match Your Measurements to a Frame Size

Once you have your numbers, compare them to the chart row by row. Use this as a rough guide when you start:

Frame size Typical rider height What to check next
XS / S Shorter riders Confirm reach to handlebars
M Mid-range heights Check standover clearance
L / XL Taller riders Check saddle height range

If you fall between two sizes, consider the riding style. Upright, casual riding often feels better on the larger frame, while a sportier position may suit the smaller one. Manufacturers’ charts are a starting point, not a final verdict, so confirm the fit in person when you can.

Confirm the Fit Before You Buy

Two checks matter most. First, standover clearance: straddle the top tube with both feet flat, and you should have roughly an inch or more between you and the bar for a road or hybrid bike, a little more for a mountain bike. Second, reach: sit on the saddle with your hands on the handlebars. You should have a slight bend in your elbows and your back should feel comfortable, not stretched. If the bike is too long, the saddle can be dropped and the stem swapped, but a frame that is too big cannot be easily fixed.

Common Mistakes to Avoid

  • Measuring height in shoes, which adds an inch or more and can push you into the wrong size.
  • Ignoring inseam and choosing based on height alone.
  • Assuming a size from another brand matches REI’s sizing exactly.
  • Choosing a larger frame to “grow into,” which makes control and safety harder for beginners.
  • Skipping a test ride, since a short loop around the parking lot reveals fit problems quickly.

A simple tape measure or a wall-mounted measuring stick helps you get consistent height and inseam numbers, and a hardcover book works well for the inseam check. A bike fit guide or a sizing tool from the manufacturer can also help you compare models side by side.

  • A retractable tape measure for taking accurate height and inseam readings at home. View on Amazon
  • A bike-specific stand or trainer for practicing mounting and saddle height adjustments before your first ride. View on Amazon

FAQ

Is the REI bike size chart accurate for every model?

The chart gives a reliable starting point, but geometry differs between bike types. A hybrid, a road bike and a mountain bike of the same size can fit differently, so check the model’s specific geometry chart too.

Should I use height or inseam to choose my size?

Use both. Height gives a general range, and inseam helps confirm standover clearance and the right fit for your legs.

What if I am between two sizes?

Choose the size that gives you comfortable standover clearance and a relaxed reach for your riding style. If you are unsure, a test ride or a professional bike fit can settle the question.

Conclusion

Use the REI bike size chart as a starting point, then confirm your choice with accurate height and inseam measurements and a standover and reach check. A correctly sized frame makes every ride more comfortable and easier to control. If you have a medical condition or a physical limitation, consult a professional bike fitter before buying.

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.