Smith Convoy MIPS Bike Helmet Size Chart: How to Find Your Fit

By Caleb Morgan

Updated November 2026

The Smith Convoy MIPS bike helmet size chart tells you which shell size to order based on the circumference of your head, measured a little above your eyebrows. To use it well, you need a soft tape measure, about two minutes, and a quick fit check once the helmet arrives. This guide walks through measuring, reading the chart, confirming fit with the straps and dial, and avoiding the mistakes that send people back to the store.

What the Smith Convoy MIPS Size Chart Measures

Helmet sizing is based on head circumference, not height, weight or the size you wear in a shirt. Manufacturers specify a size range for each shell, and those ranges are the numbers you compare against your own measurement. Smith’s Convoy MIPS is sold in sizes that map to a span of centimeters or inches, and the exact boundaries are printed on the packaging and the manufacturer’s sizing information. Always check that current chart rather than relying on a number from a forum post, because ranges can change between model years and between road, trail and urban variants.

Shopping for one? See our guide: Dirt Bike Helmet Size Chart: 10 Best Helmets Compared in 2026.

The Convoy is a mountain-style helmet, so its fit priorities are the same as most full-coverage and trail helmets: a stable, level position on the head, a firm but comfortable pad fit, and a retention system that holds without pinching. If you are comparing it with other styles, our guide to Bike Helmet Sizes Chart: How to Find Your Right Fit in 5 Steps covers how sizing logic works across helmet types.

Step 1: Measure Your Head Correctly

Most sizing errors happen at the measuring stage, not the chart. Follow these steps:

1. Use a flexible cloth or fabric tape measure. A metal tape or string you later measure with a ruler works too, but a soft tape is easiest.
2. Remove any hair clips, hats or headbands. Wear the hair you normally ride with, since a bun or ponytail can add a few millimeters.
3. Wrap the tape around the widest part of your head, about one finger-width above your eyebrows and ears. This is the line the helmet will sit on.
4. Keep the tape level all the way around, snug but not tight enough to compress your scalp.
5. Read the number where the tape overlaps, and write it down in both centimeters and inches if you can.
6. Measure twice. If the two readings differ by more than a few millimeters, repeat the process until they match.

Tools You Need

• A soft fabric tape measure, ideally marked in both centimeters and inches
• A pen and paper or a phone note to record the number
• A mirror, so you can check that the tape is level in the back
• A second person if you want a more accurate reading, though it is not required

Step 2: Read the Chart Against Your Measurement

Once you have your head circumference, find the matching row on the Convoy size chart. If your measurement falls exactly on a boundary, the general rule is to try the size up and check fit, because a helmet that is too small causes more problems than one that is slightly large, which the retention system can often correct. Use the table below as a template for how to organize your numbers.

Step 3: Check the Fit Once the Helmet Arrives

A correct size on paper still needs a real-world check. Put the helmet on with the retention system fully open, then adjust in this order:

1. Center the helmet so the front edge sits about two finger-widths above your eyebrows.
2. Tighten the rear dial until the helmet feels snug, then stop. You should feel even pressure all the way around, not just at the top.
3. Adjust the side straps so the buckles sit just below your ears, forming a V shape around each ear.
4. Fasten the chin strap and tighten it so one or two fingers fit flat between the strap and your chin.
5. Shake your head side to side and nod forward. The helmet should move with your head and not slide backward or forward.
6. Open your mouth wide. You should feel the helmet grip slightly, which confirms the chin strap is doing its job.

Signs the Size Is Right

• The helmet sits level, covering the forehead without tilting back
• No pressure points or hot spots after five to ten minutes of wear
• The dial tightens smoothly, with room left on the adjuster
• The helmet does not move when you shake your head

Signs the Size Is Wrong

• A headache or pinching at the temples after a short wear test
• The helmet rocks forward and exposes your forehead
• The dial is at its tightest setting and the helmet still shifts
• The helmet sits high on the head, showing a large gap at the front

Tips for Fitting a MIPS Helmet

The MIPS layer, a low-friction liner designed to allow a small rotational movement during certain impacts, does not change the sizing chart. It does mean the internal fit matters just as much as the shell size. Keep the pads in place, avoid swapping them for thicker aftermarket versions unless the manufacturer allows it, and inspect the liner for any damage after a crash. If you ride in cold weather, a thin cap under the helmet can change the fit, so measure and test with the layer you will actually use.

For riders who are still deciding on a helmet type, our overview of Trail Bike Size Chart: 3 Best Picks for Finding Your Frame Fit shows how trail riding influences fit priorities, and it pairs well with helmet sizing when you are kitting out a new setup.

Common Mistakes

• Measuring over a hat or helmet liner. Always measure bare-headed or with the same thin cap you ride in.
• Measuring too loosely. A slack tape gives a larger number and pushes you toward a size that will rattle.
• Assuming a size from a different brand. Helmet sizing varies between manufacturers, so always use the Smith chart.
• Ignoring the chin strap. A helmet that does not stay put in a crash is a helmet that is not doing its job.
• Tightening the dial to fix a loose helmet. If the dial is maxed out and the helmet still moves, the size is probably wrong.
• Skipping the head shake test. It is the fastest way to catch movement before you ride.

Recommended gear

A few accessories make sizing easier and more accurate.

• A soft fabric tape measure gives the most consistent reading around the head. View on Amazon
• A thin skull cap or liner lets you test fit with the layer you will wear under the helmet, especially in cooler months. View on Amazon
• A small mirror helps you confirm the tape is level at the back of the head before you record your number. View on Amazon

FAQ

How do I measure my head for a Smith Convoy MIPS helmet?

Wrap a soft tape around your head about one finger-width above your eyebrows, keeping it level all the way around. Record the number in centimeters or inches, then compare it with the size chart.

What if my measurement falls between two sizes?

Try the larger size first and tighten the rear dial. If the helmet feels stable and comfortable without pressure, it is the right choice. If it still shifts, try the smaller size.

Does the MIPS layer change the sizing?

No. The MIPS liner sits inside the shell and does not change the size ranges. It does mean you should keep the pads and liner intact for proper fit and performance.

Can I wear a cap under the Convoy?

A thin cycling cap is usually fine for testing and riding in cooler weather. Measure and check fit with the same cap you plan to wear, because a thicker layer can change the feel.

How tight should the helmet feel?

It should feel snug with even pressure all around, without pinching or headache-causing pressure. You should be able to fit one or two fingers under the chin strap.

What should I do if the helmet still moves after adjusting?

Check that the dial is not maxed out, then confirm the side straps form a V around the ears. If the helmet still shifts, the size is likely wrong, and you should contact the seller or manufacturer about an exchange.

Should I replace the helmet after a crash?

Yes. Any helmet that takes a significant impact should be replaced, even if the damage is not visible, because the protective structure can be compromised. Check the manufacturer’s guidance for specifics.

Is a youth size chart different?

Youth sizing uses smaller ranges and is designed for younger heads. If your child falls near the edge of an adult range, check the manufacturer’s youth options rather than guessing.

Conclusion

Finding the right Smith Convoy MIPS size comes down to a careful head measurement, a quick read of the official chart, and a practical fit check once the helmet arrives. Measure with a soft tape at the right height, use the larger size if you fall on a boundary, and confirm with the dial, straps and head shake. A well-fitting helmet is the one you will wear on every ride, so take the few extra minutes to get it right.

Related reading

• Oneal Dirt Bike Helmet Size Chart: A Practical Guide (2026)
• 7 Best Youth Dirt Bike Helmet Size Chart Picks for Young Riders (2026)

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.