Most bike crashes don't look like what we picture. You don't go head first into a fixed obstacle like in a film. In reality, you slide on a root, tip sideways in a tight bend, or pitch forward after an emergency stop on wet tarmac. In these situations, the impact on the skull is oblique, rarely straight on. That's exactly where the difference between two certified helmets can matter.
All helmets sold in France must comply with and be certified to the EN 1078 CE standard. But that certification is a floor, not a ceiling. It guarantees a minimum level of protection, without distinguishing a 35 euro model from a 170 euro one. Understanding what justifies that gap, what matters for your riding, and what you can reasonably set aside: that's what this guide is for.
The EN 1078 CE standard: the starting point, not the destination
When choosing a bike helmet, first check that it carries the CE mark and complies with the EN 1078 standard.
This standard sets European requirements covering, among other things, impact absorption, the retention system, the strength of the chin strap and the helmet's construction. It's therefore an essential benchmark for confirming that a model meets the applicable regulatory requirements.
But EN 1078 isn't a ranking of helmets. Two compliant models can still differ in shape, coverage, fit, weight, ventilation or comfort.
Certain additional technologies or features may also be offered depending on the model. They don't replace a good fit: a helmet first and foremost needs to suit your riding, your head shape, and be positioned correctly.
Every helmet in the Cairn range carries the CE mark and complies with EN 1078. Which model to choose then comes down to how you ride and what you prioritise.
In-mold or ABS construction: understanding before you choose
A helmet's outer shell isn't just decorative. Its construction affects the weight, the durability, and how well the shell protects the absorbing foam underneath.
In-mould construction moulds a thin polycarbonate shell together with an EPS (expanded polystyrene) absorbing foam liner. The two elements form a single structure. The result is generally a lighter helmet, with a design that makes it easier to fit in plenty of vents.
This is a very common construction for road, XC and trail mountain bike helmets, where lightness and ventilation are especially valued on long or hard efforts.
ABS construction uses a thicker, more rigid outer shell, bonded to the absorbing foam. The helmet is usually a bit heavier, but its shell holds up better to scuffs, everyday handling and the small knocks that come with transport or storage.
For road, XC or trail mountain biking, in-mould is often preferred for its lightness and ventilation. For everyday urban use, or when outer durability is a priority, ABS can be the more sensible choice.
At Cairn, the construction chosen depends on the features each model is built for and the riding it's designed to handle.
Ventilation: when airflow becomes a performance criterion
On a short ride around town, a helmet's ventilation is a comfort feature. On a forty minute mountain bike climb, or on a road ride in 30°C heat, it's a genuine performance criterion.
The number of vents alone doesn't measure how effective a ventilation system is. What matters is how air actually moves inside the helmet, against the scalp. The Aero Flow system, which Cairn fits on several models in its range, relies on channels cut into the inner foam that carry air naturally from the front through to the rear exit. In practice, this makes a real difference on climbs or at low speed, once speed alone is no longer enough to create natural airflow.
By contrast, urban or city helmets deliberately close off some vents to gain structural strength or to fit LED elements. That's a deliberate trade-off, not a design shortcoming. The Lava and Magma from the Cairn mountain bike helmet range show clearly what active ventilation can bring on long outings.
MIPS® and rotational protection: genuinely useful, or a marketing claim?
It's the question many cyclists ask themselves before accepting a 20 to 30 euro price premium. The answer lies in what bike accidents actually look like.
A helmet's effectiveness in a cycling impact is well established. To go further still, Cairn and MIPS® worked together to build an even safer helmet for your head. Accident statistics show that falls and impacts most often produce an angled impact (under 90°) on the head. These so called "rotational" impacts can cause severe brain injury. The MIPS® system (Multi-directional Impact Protection System) is designed to absorb this rotational force and reduce its impact on the brain.
In practice, MIPS® adds a low friction layer inside the helmet. During an angled impact, this layer can shift slightly relative to the shell, reducing the rotational force transmitted to the skull.
In trail and enduro mountain biking, where speeds are high, the terrain is uneven and falls are frequent, MIPS® provides measurable protection. On road or gravel, the same logic applies as soon as you ride regularly and fast. For everyday urban riding at moderate speed, it's more a personal call.
At Cairn, MIPS® technology is available on the Edge MIPS®and, for road, the Atom MIPS®. These are the models to prioritise if the terrain is technical or the speeds are high.
Choosing by how you ride: mountain bike, road, urban, kids
The criteria don't just change with budget, they change with how you actually ride.
Trail and enduro mountain biking
Rear head coverage, fit and ventilation are among the top priorities. An in-mould helmet with the Aero Flow system and MIPS® technology covers the essentials. The Edge MIPS® also adds the Occipital Protect Zone, a structural reinforcement of the back of the head, an area particularly exposed in a backward fall. The Rift MIPS® and the Magma cover trail and cross country mountain biking. For pure cross country, riders after a lighter, more accessible helmet will find the Lava a good fit.
Road and gravel
Lightness, ventilation and long term comfort take centre stage. On long or intense rides, good airflow helps stop heat building up. Aerodynamics can also become a factor for more performance focused riding. The Atom MIPS® combines lightness, ventilation and MIPS® technology for demanding road and gravel cyclists.
Urban
The criteria change completely here. What matters is a comfortable helmet that's quick to put on and take off several times a day, stays stable on your head without fiddly adjustment, and stays visible in poor conditions. The FIDLOCK® buckle, which clips and unclips in a single motion thanks to its magnetic mechanism, answers that need directly. The Clarke models favour a wraparound design built for everyday use. Some models' clear visor also shields against wind and spray in wet weather.
Kids
The EN 1078 safety standard applies to bike helmets across Europe, whatever the rider's age, but whether a helmet is legally compulsory for children differs from one country to another, and the rules do change, so it's worth checking the regulation currently in force where you ride. Whatever the law requires, the choice should above all take into account size, weight, fit and how easy the helmet is to adjust. It needs to match the child's current head size and stay correctly positioned throughout the ride. The Sunny model is designed for balance bikes from 18 months. Browse the full Cairn kids' helmet range to find the right model for your child's age and riding.
How to find the right size and adjust your helmet
A helmet that's too big, too small or badly adjusted doesn't protect properly, even if it's certified and technically excellent. Measure your size with a soft tape measure, held about 2cm above the eyebrows, around the widest part of the head.
Cairn sizes generally follow this guide:
- S: 52 to 55cm
- M: 55 to 58cm
- L: 58 to 62cm
Always check the size guide on each product page, as ranges can vary between models.
The 360° Fit System allows millimetre precise tightening via a dial at the back. The dial adjusts the fit around the head, while the straps stabilise the helmet and keep it correctly in place. Once the dial is set, the straps should form a V around each ear, meeting just below the earlobe. The chin strap should allow one to two fingers between the strap and the chin, with no excess slack.
A simple check before every ride: push the helmet backwards with your palm. If it tips easily, the dial is too loose.
Conclusion
Choosing a bike helmet comes down to answering three questions in order: what environment am I riding in, what kinds of stresses and falls could my riding expose me to, and what matters most to me between lightness, ventilation, comfort and coverage?
The CE mark and compliance with EN 1078 are the first benchmark. Construction, fit, ventilation, retention and any additional technologies then help you choose the model best suited to how you ride. At Cairn, the main uses are covered without compromising on price, from €34.99 to €169.99.
Explore the range starting from how you actually ride: mountain bike helmets, urban helmets or kids' helmets.
