Clearly, the safest bicycle helmets incorporate some form of anti-rotational impact technology, as rotational impacts are the primary cause of concussions, as evidenced by the independent testing results released by Virginia Tech. Aside from the claims made by manufacturers, Virginia Tech’s helmet safety tests provide a useful reference. However, there are disagreements among brands regarding helmet testing standards. KASK, which does not use MIPS technology, argues that the current tests are conducted under conditions where there is a high friction coefficient between the helmet and a foam head model, which is far from the reality of a rider’s head and helmet friction. This implies that the models used in testing only reflect the friction between a bald (or near-bald) head and the helmet; if a rider has thick hair, the friction coefficient will be lower. Moreover, KASK helmets have passed the new WG11 standards set by the European Committee for Standardization (CEN), indicating complete compliance in both rotational and linear impact tests.
From left to right, the helmets are: Bontrager XXX WaveCel, Bontrager Velocis MIPS, Specialized S-Works Prevail II Vent, POC Ventral Air WF SPIN, and Lazer Z1.
They utilize: WaveCel, MIPS Evolve, MIPS Air, and SPIN technology, while the far-right Lazer Z1 does not employ any anti-rotational impact technology.
Regarding helmet safety testing standards, multiple standards exist, including CPSC 1203 and EN 1078, which are the standards for the USA and Europe, respectively, with the US standards being somewhat stricter. There are also national standards, as most helmets are produced domestically and many are exported, resulting in high safety standards. We won’t delve into helmet testing standards today; the main focus is to showcase several helmets using different anti-rotational impact technologies.
Among the top 30 helmets tested by Virginia Tech, except for one mountain full-face helmet, all others use some form of anti-rotational impact technology. MIPS remains the most popular because it is open-source and can be purchased. Next is Bontrager’s proprietary WaveCel and POC’s own SPIN technology.
MIPS and SPIN are quite similar, as the principle of reducing rotational impacts is very simple: a sliding layer is added between the helmet and the head. Without patent protection, it is easy to imitate. In fact, MIPS and SPIN have had patent disputes, which have now been resolved.
1. WaveCel
WaveCel differs from MIPS in that it is not a 1mm thick low-friction sliding layer, but rather a compressible, foldable, and sliding honeycomb structure.
Bontrager’s WaveCel is a much more complex technology developed by two brain injury experts, with the honeycomb-shaped WaveCel located inside the helmet shell. The WaveCel layer is designed to “bend, crumple, and slide,” which helps prevent impacts from various angles. The honeycomb structure dissipates impact forces in three stages, providing a buffer before any impact reaches your head. While MIPS and SPIN mainly address rotational impacts, WaveCel’s design goal is to counter all types of impacts. Thus, we can imagine WaveCel as a thickened EPS foam in the helmet; the safety function of the bicycle helmet relies on the EPS foam, and of course, the outer surface is covered with a polycarbonate shell for aesthetic purposes. High-end helmets often incorporate an internal skeleton within the foam material to prevent disintegration upon impact. Anti-rotational impact technology is just an added bonus that can enhance safety but cannot replace the role of EPS foam. Therefore, helmets that do not use anti-rotational impact technology are not inherently unsafe. WaveCel is unique, but under current testing standards, it does not score higher than MIPS and adds weight, hindering airflow; hence Bontrager also offers MIPS helmets.
This image clearly shows the structure of WaveCel, which is quite thick. Bontrager confidently claims that WaveCel improves concussion protection by 48 times compared to standard helmets, leading to significant disputes with MIPS.
2. MIPS
MIPS essentially consists of the sliding “plastic shell” inside the helmet, anchored to the helmet via rubber strips. It is very smooth with low friction, allowing it to slide relative to the helmet in any direction.
Very thin and smooth plastic liner
Anchored to the helmet by elastic rubber strips, allowing the liner to slide freely
Recently, MIPS has renamed their products to make it easier to distinguish different levels of protection performance, and they also released the MIPS Integra system, which is integrated into the helmet; however, this has not yet been used in bicycle helmets. MIPS Air, Evolve, and Essential are the new names that highlight the main features of these systems. Essential is the most basic protection system but sacrifices weight and breathability. Evolve is very suitable for bicycle helmets, akin to the relationship between bread and butter, providing a good fit, lightweight, and breathability; the showcased Bontrager Velocis uses it. Air is the newest, lightest system that uses a sliding liner anchored by elastic rubber, providing optimal ventilation; the showcased S-Works Prevail II Vent uses it.
The S-Works Prevail II Vent focuses on ventilation, thus it uses the new MIPS Air technology, and you can see that the inside of the helmet no longer has the plastic shell, only some sliding liners anchored by rubber, which look similar to helmets without anti-rotational impact technology.
The rubber anchor bears the MIPS mark, indicating it is MIPS patented technology
This photo of the liner illustrates its principle; the back side of the liner has a low-friction layer, anchored to the helmet by rubber. The friction between the rubber anchor and the liner is very low, allowing it to slide freely for 10-15mm.
3. SPIN
SPIN’s concept is simple yet ingenious; the silicone liner inside the helmet eliminates hard contact between the head and the helmet, absorbing impact forces from any direction through the sliding silicone liner.
POC Ventral Air WF SPIN may look similar to a regular helmet inside, except for the blue SPIN liner.
You might not expect that what makes SPIN work is this helmet liner, which differs from regular liners in that it has a silicone layer inside, allowing it to slide while also enhancing comfort.
The Lazer Z1, which does not have rotational impact protection technology, only has a sponge liner inside, but this helmet has also passed the CPCS certification, making it sufficiently safe for use.
Although the principles of the anti-rotational impact technologies used in helmets are quite simple, MIPS has profited greatly from its patents. Additionally, don’t ask BX-kun which helmet is the safest, BX-kun will not test that, and a separate article will be written for trials of several new helmets.
Finally, here are the weights of the helmets:
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Bontrager WaveCel XXX M/L size——385g
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Bontrager Velocis MIPS S/M size——277g
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Specialized S-Works Prevail II Vent M size——252g
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POC Ventral Air WF SPIN M size——267g
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Lazer Z1 L size——266g
How to Improve Ventilation by 20%, the S-Works Prevail II Vent’s Ingenious Design
Testing the Lazer Z1 Helmet for Ventilation and Comfort in the Hot Summer
Comfort, Ventilation, and Aerodynamics: Testing the POC Ventral Air WF SPIN Asian Version Helmet
