Caleb MorganBy Caleb Morgan

Updated November 2026

A royce union bike size chart is a height-and-inseam reference that points you to the frame size most likely to fit your body. This guide shows you how to read that kind of chart, take two quick measurements at home, and confirm the result with a short test ride. By the end, you will know which frame size to start with and what to check before you buy.

Understand What the Chart Is Actually Measuring

Most size charts list frame sizes such as small, medium, large, or numbered sizes in centimeters or inches, then pair each one with a rider height range. Some also list inseam ranges, which matter more for road-style frames. Frame size usually refers to the seat tube length, measured from the center of the bottom bracket to the top of the seat tube, but brands measure this differently. Always check the specific chart published by the manufacturer you are considering, because a “medium” from one brand can differ noticeably from another.

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

Measure Your Height and Inseam at Home

Take two measurements before you look at the chart. Accurate numbers make the difference between a good fit and a frustrating one.

  1. Stand barefoot against a wall with your heels about 2 inches apart and your back straight. Mark the top of your head, then measure from the floor to the mark.
  2. Stand with your back against a wall and place a hardcover book between your legs, spine snug against your crotch. Raise the book until it sits firmly, then measure from the floor to the top edge of the book.
  3. Subtract a small margin from the inseam if you ride in soft-soled shoes, since shoe thickness shifts your effective height slightly.
  4. Write both numbers in centimeters and inches so you can compare them against whichever units the chart uses.

Match Your Numbers to the Chart

Find the row that matches your height first, then check whether your inseam falls within the range listed for that row. If the two measurements point to different sizes, favor the inseam for road and gravel-style frames and favor height for upright or hybrid bikes, where reach matters less. When you land between two sizes, the smaller frame usually feels more agile and the larger one more stable at speed. Beginners tend to do better on the smaller option because it is easier to control at low speeds.

Your measurement What it suggests
Inseam falls between two sizes Try the smaller size first for easier handling
Height and inseam point to different sizes Prioritize inseam for road-style frames, height for upright bikes
You plan to ride mostly on paved paths Lean toward the size that keeps your torso upright

Confirm the Fit Before You Commit

A chart gives you a starting point, not a guarantee. Once you have a candidate size, check these points in person or with the seller’s return policy in mind:

  • With the saddle level, you should be able to stand over the top tube with about one to two inches of clearance.
  • When the pedal is at its lowest point, your knee should have a slight bend, not be fully locked out.
  • Your reach to the handlebars should let your elbows stay slightly bent, not stretched.
  • Ride a short loop and check that you can brake comfortably without rising off the saddle.

If you are unsure about a fit, a bike shop can adjust the saddle height, stem, and handlebar position to close small gaps. Many of the sizing principles covered in articles like Women's Bike Size Chart: How to Find Your Right Frame Fit also apply across brands, so they are worth reading alongside any chart.

Common Mistakes

  • Measuring inseam in socks or with a loose book that slides down.
  • Choosing a larger frame to “grow into,” which makes early rides awkward and tiring.
  • Assuming two brands’ “medium” frames are identical.
  • Ignoring the stack and reach numbers on the chart when comparing with another model.
  • Skipping the test ride, even when the chart looks like a clear match.

A few accessories make sizing easier to get right at home:

  • A rigid metal tape measure gives cleaner readings than a fabric one for height and inseam. View on Amazon
  • A hardcover book or a dedicated bike inseam tool keeps your inseam measurement consistent from one attempt to the next. View on Amazon

FAQ

Should I size a bike by height or inseam?

Inseam is generally more reliable for road and gravel frames because it relates to standover clearance and leg reach. Height is a useful cross-check, especially for upright bikes where the cockpit matters more than the top tube.

What if I fall between two sizes on the chart?

Try the smaller size first, since it is easier to control for beginners. Confirm with a test ride and check that your reach and standover still feel comfortable.

Can I rely on the chart alone when buying online?

A chart is a solid starting point, but it does not account for your riding position preferences or proportions. If possible, test ride a bike or buy from a seller with a clear return policy, and consult a qualified bike fitter if you have back, knee, or neck concerns.

Conclusion

Measure your height and inseam carefully, match them to the chart, and choose the smaller size when you fall between two options. Confirm the fit with standover clearance, knee bend, and reach checks before you ride. A few minutes of measuring now will save you from months of an ill-fitting bike.

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.