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How to Choose Motocross Jersey Size: The Complete Fit Guide 2025
Buying a motocross jersey seems simple until you actually try to size one. Unlike streetwear, where you can just grab your usual t-shirt size and call it a day, motocross jerseys use brand-specific sizing that can vary wildly. A medium in Fox Racing might fit like a small in Fly Racing. Add in the fact that jerseys are designed to be worn over chest protectors and roost guards, and suddenly that “just order my normal size” plan starts looking risky.
If you’ve ever ended up with a jersey that’s too tight across the shoulders, too baggy in the sleeves, or so short it rides up every time you lean forward on the bike, this guide is for you. We’re going to break down exactly how to choose motocross jersey size so you get it right the first time — no returns, no guessing, no frustration.
Why Motocross Jersey Sizing Is Different From Streetwear
Here’s the thing that trips up most riders: motocross jerseys are not sized like regular shirts. They’re cut to accommodate protective gear underneath, which means they tend to run larger in the chest and shoulders. The sleeves are designed to be longer so they don’t pull up when you grip the bars, and the torso is cut with a slight forward lean in mind — because you’re not standing up straight when you ride.
This means two things: First, if you wear a medium t-shirt, you might actually need a small or medium jersey depending on the brand. Second, if you plan to wear a chest protector — and you absolutely should — you need to account for that extra bulk. For more on why protective gear matters, check out our guide on the best motocross helmets 2025, which covers safety ratings in depth.
The general rule of thumb: if you ride without a chest protector, size down one from your t-shirt size. If you ride with a roost guard or chest protector, stick with your normal size or even size up if you’re between sizes.
How to Measure Yourself for a Motocross Jersey
Before you look at any sizing chart, you need three measurements. Grab a soft measuring tape (or a piece of string you can measure afterward) and take these readings:
- Chest: Measure around the fullest part of your chest, keeping the tape level across your back. If you wear a chest protector, measure over it.
- Waist: Measure around your natural waistline, which sits just above the hip bones. Jerseys aren’t tailored at the waist like pants, but this helps if you’re buying a gear set.
- Sleeve length: Measure from the center of the back of your neck, across the shoulder, and down to your wrist with your arm slightly bent.
Write these numbers down. You’ll need them to cross-reference with each brand’s sizing chart. And if you’re also shopping for pants to complete your gear set, our complete dirt bike sizing guide walks you through the full head-to-toe fit process.
Brand-by-Brand Sizing Differences
This is where most riders get burned. Motocross brands do not share a universal sizing standard. Here’s what you need to know about the major players:
Fox Racing
Fox Racing jerseys tend to run true to size or slightly large. Their popular Fox Racing 180 Gear Set is one of the most consistent-fitting options on the market, making it a great choice if you’re buying online and can’t try before you buy. If you wear a large t-shirt, a large Fox jersey will likely fit well — maybe slightly roomy, which is perfect if you run a roost guard underneath.
Fly Racing
Fly Racing jerseys tend to run about half a size smaller than Fox. Their Fly Racing Kinetic Gear Set is a mid-range option with a more athletic, tailored cut. If you’re between sizes on Fly, go up — especially if you wear protection under your jersey. The Kinetic line specifically has a more tapered fit in the arms, which some riders love and others find restrictive.
Alpinestars
Alpinestars jerseys run slightly small in the chest but true to size in length. They’re cut with a more European fit profile — leaner and longer. Riders with broader builds often need to size up one full size in Alpinestars compared to their t-shirt size.
Troy Lee Designs
TLD jerseys run true to size with a slightly relaxed cut. They’re known for some of the best ventilation in the industry, with mesh panels that keep you cool. The fit sits somewhere between Fox and Fly — not as roomy as Fox, not as tight as Fly.
Jersey Fit Types: Race Fit vs. Relaxed Fit
Not all motocross jerseys are cut the same way, even within the same brand. Understanding the difference between race fit and relaxed fit will help you choose the right one for your riding style.
Race fit jerseys are tighter, shorter, and more form-fitting. They’re designed for competitive riders who want zero excess material catching the wind or snagging on branches. Race-fit jerseys have shorter tails (the part that tucks into your pants) and tighter sleeves. If you ride motocross tracks and want every aerodynamic advantage, this is your cut.
Relaxed fit jerseys are longer, roomier, and more comfortable for all-day riding. They’re the go-to for trail riders and weekend warriors who prioritize comfort over aero. The extra room also makes it easier to fit bulkier chest protectors underneath. Most entry-level and mid-range gear sets — like the Fox 180 and Fly Kinetic lines — default to a relaxed fit.
If you’re unsure which to get, relaxed fit is the safer choice. You can always go race fit later once you know your exact size.
Should You Size Up for a Chest Protector?
This is one of the most common questions we get, and the answer depends on what you’re wearing underneath. If you run a basic roost guard (the lightweight plastic deflector type), your normal jersey size should work fine — these are thin enough that most jerseys accommodate them without sizing up.
If you wear a full chest protector with shoulder pads and back coverage — like a Leatt or Alpinestars Bionic — you may need to size up one size. These are bulkier and can make a true-to-size jersey feel tight across the shoulders and chest. The jersey should move freely without pulling at the seams when you’re fully geared up.
Quick test: put on your chest protector, then try on the jersey. Raise both arms to shoulder height and lean forward into a riding position. If the jersey pulls uncomfortably at the shoulders or rides up past your pants waistline, it’s too small.
Signs Your Jersey Is the Wrong Size
Here’s a quick checklist to help you figure out if you got the size wrong:
- Too tight: The jersey pulls across the chest when you reach forward, the sleeves restrict your arm movement, or the collar chokes you when you look over your shoulder.
- Too loose: Excess fabric billows around your midsection, the sleeves extend past your wrists and bunch up near your gloves, or the jersey looks like a tent when you’re standing upright.
- Too short: The tail pulls out of your pants when you lean forward, exposing your back to roost and debris. This is a safety issue, not just a comfort one.
If any of these apply, it’s time to swap sizes. Most retailers (including RMATV, where our affiliate products are sourced) offer exchanges within 30 days.
Youth vs. Adult Sizing
If you’re buying for a younger rider, youth motocross jersey sizing is a whole different ballgame. Youth sizes typically run from XS (roughly ages 4-6) through XL (roughly ages 14-16), but there’s no industry standard. A Fox Youth Medium won’t necessarily match a Fly Youth Medium.
The best approach for youth sizing is to measure the rider and check the brand’s specific youth sizing chart. When in doubt, size up — kids grow fast, and a slightly loose jersey is better than one they outgrow in three months.
Caring for Your Jersey to Maintain Fit
Once you’ve got the right size, you want it to stay that way. Motocross jerseys take a beating — mud, sweat, wash cycles — and improper care can shrink or warp the fit over time. For a detailed breakdown of cleaning best practices, check out our complete motocross gear washing guide.
The short version: wash in cold water, use a mild detergent, skip the fabric softener (it degrades moisture-wicking fabrics), and hang dry. Never throw your jersey in a hot dryer — the heat can shrink the polyester and ruin the vented panels.
Our Top Jersey Recommendations
Based on fit consistency, durability, and value, here are our top picks:
Best Overall: The Fox Racing 180 Gear Set remains the gold standard for reliable sizing. It’s relaxed enough for trail riding, not so baggy that it catches wind, and the sizing chart is accurate within one inch. At its price point, it’s the jersey we recommend to most riders.
Best Value: The Fly Racing Kinetic Gear Set offers a more tailored fit at a competitive price. If you prefer a slimmer profile and don’t mind sizing up, this is an excellent option. The ventilation is above average for the price range.
Final Tips for Getting It Right
1. Always check the brand-specific sizing chart — don’t assume your t-shirt size translates directly.
2. Measure yourself (or have someone help) rather than guessing. Those three numbers — chest, waist, sleeve — eliminate 90% of sizing mistakes.
3. If you’re between sizes, size up for relaxed-fit jerseys and size down for race-fit jerseys (unless you wear a full chest protector, in which case always size up).
4. Read the fit notes on the product page. Most retailers list whether a specific jersey runs small, true to size, or large.
5. When buying a complete gear set, use the jersey size as your guide and match the pants accordingly. If you need help with the full kit, our helmet guide and dirt bike sizing guide round out the rest of your gear shopping.
Get the size right, and you’ll barely notice you’re wearing a jersey at all — which is exactly how it should feel on the track or trail.