Riding Helmet: MIPS, Size and Safety — How to Choose and Fit It Properly
You’ve understood the essentials of choosing a helmet and now you’re asking the real technical questions: what exactly does MIPS do? How is it different from EPS? And above all, how can you be sure to pick the right size and properly adjust your helmet? This guide is here for that. It complements our complete guide to choosing your riding helmet by going further on two points that come up repeatedly in the shop: anti-rotation technologies and fitting. At Sellerie Bucéphale, we take the time to have you try on, measure, and adjust — here is our method.
MIPS, EPS: what is the purpose of the anti-rotation shell?
A riding helmet actually layers several elements that each have a different role. To choose well, you need to understand who does what.
EPS: the foam that absorbs the shock
Beneath the rigid outer shell (often made of ABS, a durable plastic), lies the real safety component: a layer of EPS foam (expanded polystyrene, Expanded Polystyrene). This is what absorbs the energy of an impact by compressing. An important principle follows: this foam deforms only once. After a shock, even without visible cracks, it has done its job and no longer protects in the same way — which is why a helmet must always be replaced after a fall with a head impact.
MIPS: reducing rotational forces
The MIPS (Multi-directional Impact Protection System) is an anti-rotation technology. Specifically, it is usually a thin internal layer that can slide slightly (a few millimeters) between the head and the shell. The physical idea is this: in real life, falls rarely happen perfectly vertically. Most falls cause an oblique impact, which transmits a rotational movement to the head. The principle of MIPS and equivalent systems is to allow this slight sliding to reduce the rotational forces transmitted, whereas EPS mainly manages the “direct” impact.
MIPS or EPS: it’s not “one or the other”
This is the most common confusion. MIPS and EPS are not opposed: they work together. Every compliant helmet has an absorption shell (EPS or equivalent material); some models add an anti-rotation system like MIPS on top. Summary:
| Component | Role | What it manages |
|---|---|---|
| Outer shell (ABS…) | Rigidity, puncture resistance | Distributes the impact, protects from objects |
| EPS foam | Energy absorption | The “direct” impact (compression) |
| Anti-rotation system (MIPS, equivalents) | Internal sliding | Rotational forces (oblique impacts) |
Lifespan: does MIPS age?
The lifespan of a helmet doesn’t primarily depend on MIPS, but on the whole: the foam and materials age over time, with sweat and UV exposure. Manufacturers generally recommend replacing a helmet about 3 to 5 years after its manufacturing date (often engraved inside the shell), and immediately after any significant impact. A helmet equipped with an anti-rotation system follows the same logic: always refer to the model’s manual, and never buy a used helmet if you don’t know its history.
What size? How to measure your head circumference
The best helmet in the world doesn’t protect if it doesn’t fit you. The good news: measuring your head circumference takes just a minute.
- Use a flexible measuring tape (a sewing tape). If not available, use a string that you then measure against a ruler.
- Place the tape around the skull, at the widest point: about one centimeter above the eyebrows and above the ears.
- The tape should be perfectly horizontal, neither tight nor loose. Note the measurement in centimeters.
This measurement is your starting point. It corresponds to the sizes indicated by brands, often expressed in centimeters or letters (XS, S, M, L). Note: the correspondences vary from one manufacturer to another — an “M” does not have exactly the same value across all brands. For purely indicative purposes, here are common references found on the helmets we distribute:
| Head circumference | Indicative size |
|---|---|
| 48 – 52 cm | XS (child / small head) |
| 53 – 56 cm | S |
| 55 – 58 cm | M |
| 58 – 61 cm | L |
Guidelines given for reference only: always rely on the precise size guide of the chosen model. Many helmets also have a adjustment dial at the back that fine-tunes the fit within the same size.
Finally, beyond head circumference, each brand sometimes offers several shell shapes (round, oval, narrow). To identify yours, look at your skull from above: a rather circular outline = round shape, an elongated outline from front to back = oval shape. A shell adapted to your shape fits the head without pressure points on the forehead or temples.
Check the proper fit
Once the helmet is on your head, a few simple tests can tell if it fits well — even before fastening the chinstrap:
- It stays on by itself. Tilt your head forward and shake gently: the helmet should neither slip nor fall off, without the chinstrap fastened.
- It does not tilt. It stays well positioned, the front just above the eyebrows, without shifting backward or falling over the eyes.
- It does not tighten painfully. The hold is firm and enveloping, but without any pressure points or red marks on the forehead after a few minutes.
- No space to slip several fingers between the shell and the skull.
Next comes adjusting the chinstrap: once fastened, you should be able to fit one to two fingers between the strap and your chin — neither too loose (the helmet would move on impact) nor too tight (uncomfortable). The harness (ideally 3-point, with straps joining on either side of the ears) should frame the ears without covering them. A properly adjusted and fastened harness is also required in FFE competitions.
If you hesitate between two sizes or shell shapes, nothing beats trying them on. Come see us: we take the time to let you try several models to find the perfect fit.
Safety and standards: stay cautious
Whatever the technology (MIPS or not), compliance is the foundation. In Europe, a riding helmet is personal protective equipment: it bears the CE marking under the PPE regulation (EU) 2016/425, supported by a testing standard. Several standards coexist today — the test standard VG1 (VG1 01.040 2014-12), EN 1384:2023 (the old EN 1384 was withdrawn in 2014, so a mention of "EN 1384" without a year alone no longer makes sense), or recognized foreign standards such as PAS 015, ASTM F1163, or Snell E2016.
Our advice is simple: check the label sewn inside the shell and the current certification of the model, rather than relying on a single standard. The exact certification is on this label and in the manufacturer's instructions; if in doubt about a specific model, ask us, and we will confirm the manufacturer's information. And remember: price does not equal safety — a compliant, well-fitted entry-level helmet protects; the budget mainly affects comfort, ventilation, finishings, and technologies.
Our helmets
Here is a selection of helmets available at Sellerie Bucéphale, from entry-level to more advanced models. Prices, sizes, and available colors are indicated on each product page.
Selection given for informational purposes: available models, sizes, and colors may change. The presence or absence of an anti-rotation system depends on each model: refer to the product sheet and manufacturer’s manual, or ask us.
FAQ
What is the difference between MIPS and EPS?
EPS is the shock-absorbing foam that compresses to absorb direct impact: it is the safety component present in every compliant helmet. MIPS is an added anti-rotation technology: an internal layer that slides slightly to reduce rotational forces during an oblique impact. They do not oppose each other; they complement each other.
Is MIPS essential?
It’s a useful extra feature designed to better manage oblique impacts. But it does not replace a compliant helmet that fits well and is properly adjusted, which remains the foundation of protection. A helmet without anti-rotation, if well-fitted and certified, still protects.
How do I measure my head circumference for a helmet?
Using a flexible tape measure, measure around the widest part of your skull, about one centimeter above the eyebrows and ears. Note the measurement in centimeters and compare it to the size guide of the chosen brand, as sizing varies between manufacturers.
How do I know if my helmet fits well?
Without fastening the chinstrap, it should stay on by itself when you tilt and shake your head, without tipping or sliding, with firm support but no painful pressure points. Once the chinstrap is fastened, you should be able to fit one to two fingers between the strap and your chin.
How often should you replace a helmet with MIPS?
Like any helmet: about 3 to 5 years after the manufacturing date (often engraved inside), and immediately after any significant head impact. The anti-rotation system does not change this rule; refer to the model's manual.
Is a more expensive helmet safer?
Not necessarily. As long as a helmet is compliant and well-fitted, it protects. The price mainly affects comfort, ventilation, weight, finishes, and technologies like anti-rotation or adjustment systems.
Need help measuring your head circumference, choosing your shell shape, or adjusting your helmet? We are here to assist you.
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