Road cycling helmets are visibly different from mountain biking helmets. It’s not only in style but also in comfort, aero and safety.
Mountain biking helmets have a visor, a bulkier design, a low-cut rear and usually more weight than the more compact, aerodynamic, well-ventilated road bike helmets.
While some safety features are shared, they are designed to handle very different types of crashes. That’s why there are different safety considerations for road and MTB helmets.
Road helmets are primarily required to absorb and distribute the initial impact, while MTB helmets need to have good all-around surface protection since the head can hit the ground multiple times at any one angle during a fall.
#1 Helmet visors (peak)
The most obvious visual cue distinguishing mountain bike helmets from their road and urban counterparts is obviously the long visor. It’s what’s recognizable across all MTB disciplines, for half-shell and for full-face helmets alike.
They aren’t just for show either. Helmet visors or peaks have very specific purposes important to mountain bikers like shielding the face from the sun and low-hanging tree branches. But certainly don’t help aerodynamics.
#2 Ventilation ports
Another difference visible at first glance are the air vents. Road bike helmets are clearly on top here, both in size and number.
On the road, the average speed is usually higher and the surface smooth. While on the trails gravel, dust and tree branches in the air are a real issue. Nothing you’d want to get into your helmet through big air vents.
But more air holes mean less helmet shell volume absorbing hits. More holes = less absorption
#3 Shape & design
Even if you can’t quite put your finger on it, road and MTB lids just seem to be designed very differently. Not just in the paint jobs and colors used, but in all shapes and accents.
There are generally more edges on MTB lids with their traditionally very aggressive designs. Although some brands have come out with rounder designs recently, which helps with reducing rotational impacts.
On the other side, road helmets look more fluid, like a waterdrop in the overall shape. And it’s no coincidence. It’s the ideal design for aerodynamics. And while helmets can look cool, that’s obviously not their primary function
#4 Back-of-the-head protection
Mountain bike helmets also feature a lower-cut rear. This is partly due to needing a secure fit. The ratchet system at the back for an optimally tight fit is universally used in all modern helmet types.
Road helmets have started to adopt the low-cut design recently. However, the overall contact area between helmet and head is only one aspect of protection.
#5 Over-ear designs
With more area covered on the rear, some MTB helmets even extend forward over the ears and jaw.
Something not seen on roadie lids. Helmets with over-ear designs even offer some protection to the jawline without a full chin bar around the front.
Although, access to your earbuds is drastically limited …
#6 Chin bars
When the going gets rough, additional protection for the lower part of the face is a must. But there are significant downsides to breathability, weight, and aero for the benefit of full-face protection. That’s why they’re used for downhill MTB riding only.
Chin bars are an MTB-exclusive feature. Some newer convertible MTB helmets – like the Giro Switchblade I use – even allow removing them.
#6 Safety & injury protection
The differences in overall design we discussed until now all add up to differences in safety between MTB and road bike helmets. While mountain bike helmets generally offer more head coverage with thicker EPS foam, road helmets have better lab test results regarding brain injury prevention.
Different types of riding require different types of protection. The helmets for each discipline are designed for different purposes and common crash situations.
Get-offs on steep, uneven trails often result in bikers tumbling down the mountain with lots of rotational forces from trail obstacles grabbing the helmet. Every bit of coverage helps here.
While on the road, crashed riders usually slide on the pavement after a particularly hard initial impact. It’s actually helpful if the helmet has space to move on the head to not transmit all of the impact force onto the head.
The core safety technologies, however, are the same in the top-end models. One welcome innovation over the recent years is MIPS, found in MTB and road helmets.
This Multi-directional Impact Protection System (MIPS) technology is basically a helmet insert designed to create a slip-plane layer between the helmet shell and the biker’s head. In case of a crash, the slip plane reduces rotational forces to the head which are a main cause for concussions and brain injuries for cyclists.
#8 Overall weight
With more actual material in the helmet, MTB helmets are bound to be heavier. Most of this extra weight is contributed by the bulky design with a thick shell and the expanded rear.
This is also a major reason why there are specific cross-country MTB helmets available, that look and feel very similar to road lids. Without a visor and with the overall sleek designs, only the low-cut rear reminds of the mountain biking roots.
Low wind resistance is key in road cycling. Less so for mountain biking, where most of the time is spent riding uphill at a slow pace. The teardrop shape, no visor and a slim profile all contribute to a good aero performance.
#10 Chin strap closure
This is a minor detail, but something any roadie will notice when putting on an MTB helmet for the first time.
While most road bike lids and some MTB lids have a regular buckle closure, a D-ring design is also common – especially on beefier helmets for gravity ridings like downhill and enduro. There is practically no way this system is going to open with force or by accident.
#11 Goggles or sunglasses compatibility
Needless to say, big MTB goggles need 2 inches of even surface around the back for the straps to sit securely. And a bit of clearance from the eyebrows to the top of the helmet. Something most road helmets don’t provide.
Any over-ear and full-face helmets will lead to pressure points on the frames of regular sunglasses and should be worn with goggles.
Any other helmet is fine with sunglasses.