MIPS Cycle Helmet Testing
In the last few years, when shopping for a cycle helmet, chances are you would have encountered one with a MIPS addition and could easily recognize it through its yellow linings and dot on the outer part.
MIPS
MIPS, which is an abbreviation for Multi-directional Impact Protection, is a safety component that more than 120 organizations use in their headgear. In 2020, over 729 helmets containing MIPS technology were commercialized, with more than 7.3 million units purchased.
Many kinds of helmets utilized MIPS technology, such as those worn while cycling, riding a horse, building, and motorcycling.
The MIPS system is a layer inserted in between the EPS foam and the helmet liner that allows the helmet to slide up to 10 to 15mm in any direction with minimal resistance. The goal of this is to minimize the movement transmitted to your brain.
Studies have found that, while impacts which occur directly along the head can cause skull fractures and haemorrhaging, rotational impacts can cause concussion and severe head trauma, according to MIPS.
How does MIPS work
In a nutshell, MIPS minimizes the transmission of rotational impacts to your brain by using a sliding layer. As one might assume, the matter is much more intricate than it seems.
At its core, MIPS technology mimics your head’s own protective structure. Between your skull and your brain is a layer of cerebrospinal fluid,
It is logical to consider any instance in which you have tumbled off a bicycle or just stumbled. It is very unlikely that you would fall to the ground and just experience a straight-line force—there is usually an angle involved.
Peter Halldin, chief technical officer at MIPS, explains what happens when you fall at an angle and how the MIPS system counteracts the rotational forces caused because of this:
When you hit the floor, you have a forward movement in a horizontal direction, and the force of the impact creates a tangential force that causes the helmet and head to rotate.
We use the MIPS system to simulate someone slipping on ice. Instead of having the head “grab” into the ground and causing rotation, it’s like we are smoothly sliding on ice and can keep going in the direction we were meant to go.
The sliding layer within the helmet reduces the exposure of the head and brain to hazardous rotational force when an impact occurs, allowing them to both remain on a linear course.
It’s important to remember that the window for a helmet to protect against serious brain injuries is quite small.
“It is a very quick impact,” explains Halldin. The effects last for approximately 5-10 milliseconds. During the brief period, there is a large amount of force and speed exerted on the head. It is akin to having an extra heavy weight resting on the crown of your head.
Halldin claims that MIPS makes it possible for one to still move one’s head with the applied pressure and emphasizes that a helmet without a low friction layer would not be able to be adjusted on the head in the same way.
Importance of rotational force protection
MIPS
The team at MIPS have come up with two comparisons to highlight why it is crucial to stop angular forces from being transferred to the brain.
Halldin claims that the human brain is comparable to water when it comes to its characteristics.
Like water, the brain cannot be compressed. Halldin hypothesizes that if exposed to a linear force, the centre of a bowl of water or a human head experiences very little deformation. However, if a twisting force is applied, the strain values at the centre will be greater.
Marcus Seyffarth, chief of product design at MIPS, uses an illustration of stretching a rubber band to explain what influence these strain readings can have.
The more you pull an elastic band, the less easily it will go back to its original form, and the same can be applied to mental workings in the brain.
If a small amount of rotation takes place in the brain, no impact will be felt. If you suffer a mild concussion, you will be alright in the end, although it may not be comfortable. If you receive more than a small amount of trauma to the head, you could suffer a serious traumatic brain injury.
This serious damage to the brain can be displayed in various forms. The axons, or nerve fibres, in the brain can be cut, leading to diffuse axonal injury (DAI). Furthermore, the veins can rupture resulting in a subdural haematoma where blood accumulates between the brain and the skull. This can bring about different indications ranging from feeling nauseous to paralysis on one side of the body.
Does MIPS affect helmet size?
When MIPS initially rolled out its technology to the public, it implanted the sophisticated features into already existing helmets that were available for sale.
This resulted in a decrease in the dimension of the helmet because MIPS was introducing an extra layer with a measure of 0.5 to 0.8mm, which consumed some of the available space for the head.
Nevertheless, occurrences of this kind are much rarer nowadays, seeing as MIPS collaborates with helmet makers right from the design stage, embedding the protection features into them right off the bat.
This implies that companies can factor in the amount of room that MIPS requires and maintain their sizes as they were original.
Helmet Testing: MIPS
We went beyond what is necessary for bicycle helmets to be sold when assessing their safety of them by carrying out tests on six helmets.
Despite the reality that most bicycle head collisions happen at an angle, the majority of countries call for bike helmets to pass straight-impact tests to be sold.
Testing done by the US Consumer Product Safety Commission and the European Union’s Certification Network requires helmets to be dropped onto a flat, hard surface with an interior headform fashioned similarly to a human head, complete with weights and at least one accelerometer to measure the deceleration caused by the force of impact.
The crushable expanded polystyrene (EPS) foam liner effectively decreases the head’s velocity of motion in the majority of helmets.
The certification process for helmets entails dropping them onto different parts of the helmet (such as the top, front and sides), yet it does not simulate a crash typical of bike collisions with a hard angled surface.
Nonetheless, angling the anvil and topping it with sandpaper before the helmet with the instrumented headform inside hits it will make the helmet spin when it impacts.
Halldin has advocated for the incorporation of a 45-degree tilted incline into global helmet certification regulations, which undergo revisions every 5-15 years.
Our MIPS Helmet Test
The Virginia Tech Helmet Lab, which is responsible for developing the STAR helmet ratings for cyclists, tested six helmets for the magazine ‘VeloNews’ using a technique that measures both the perpendicular and rotational forces on the brain when an impact occurs.
In total, six different helmet models were tested that included two variations of the Rudy Project Racemaster, the Lazer Z1, and the Scott Spunto junior helmet, one with MIPS technology and one without.
We couldn’t compare helmets with non-MIPS anti-rotation technologies to those without them because the technology is built into the padding and thus it would be impossible to accurately assess the difference. This is because the helmets with such systems are so diverse from those without that a range of factors would be impacted.
At Virginia Tech, the STAR bicycle-helmet impact-testing process consists of dropping a helmet-enclosed NOCSAE instrumented headform onto a steel post that has been angled at 45 degrees and covered in 80-grit sandpaper which is changed after every fourth trial.
This examines how efficient a helmet is at preventing both the linear momentum and rotational speed of a person’s head from a cycling accident.
At Virginia Tech, the Summation of Tests for the Analysis of Risk (STAR) values are calculated by taking the average of the potential risks of head injuries that come from various sorts of helmet-impact testing setups.
The STAR system works out the outcomes from many different helmet assessments into one score (1-5 stars); it was initially made to figure out the probability of a college football player sustaining a concussion while wearing a certain helmet during a season.
A formula for calculating the potential risk of injury from concussion was created using the head-impact data obtained from sensors placed inside college football players’ helmets that had previously been diagnosed with concussions.
Testing bicycle helmets using the STAR approach was modified to now involve angular velocity, which has a close relationship to how much strain is placed on the brain that can cause concussions.
MIPS Helmet Testing Results
The Virginia Tech Helmet Lab administered two separate STAR evaluations on each headgear- first on the side (at point 1) and the second on the temple region on the opposite side (at point 2).
The speed at impact was 4.8 meters per second (10.7mph). The NOCSAE headform featured three accelerometers that measured the peak linear acceleration in terms of G-force, and its triaxial angular rate sensor documented the peak angular velocity, which is the same as peak rotational velocity.
The probability of experiencing a concussion was figured out by adding the PLA and PAV measurements into the injury-likelihood computation. A 0.10 risk rate is indicative of a 10% chance of sustaining a concussion.
For both impact locations, all PLA, PAV, and potential concussions were much less with the MIPS model than with the non-MIPS version.
At side impact, the concussion risk with the MIPS helmet was substantially lower than that of the non-MIPS Spunto, with a calculated risk that was only 16% of the latter.
The Rudy Project Racemaster had the least amount of risk reduction with a MIPS layer at the impact location 1, whereby the risk of concussion with the MIPS layer was only 74% of what the risk would be without a MIPS layer.
The Lazer Z1 saw approximately 50 per cent fewer concussions in side impacts (location 1) when wearing a MIPS layer, and around two-thirds fewer concussions in temple impacts (location 2).
Testing Drawbacks
It is necessary to run tests to determine how effectively the helmet will guard the individual who is wearing it in actual impacts. This necessitates the fabrication of more interfaces than current helmet testing takes into account.
Merely altering the angle of the impact surface and adjusting its coefficient of friction to emulate the collision between a helmet and the ground during a bicycle accident is not sufficient.
Accurately replicating the contact point between the scalp (or hair) and the helmet as well as the connection between the skin and the skull is necessary; contemporary head forms do not fulfil that requirement.
The following three commonly utilized head forms for impact testing of protective headgear wear for sports are the Hybrid III (known as “HIII”), developed for vehicle crash assessment, the magnesium EN960, which is employed for European motorcycle helmet trials, and the NOCSAE (National Operating Committee on Standards for Athletic Equipment), designed for tests on helmets used for football, hockey (ice and field), baseball and softball, polo, and lacrosse.
In addition to the magnesium EN960, these head forms have a vinyl or polyurethane coating covering them. The head form has that surface connected to it rather than loosely sliding on the skull like human skin does, and it is also more adhesive than the human scalp, regardless of whether there is hair or not.
Research has revealed that the contact force resistance of artificial heads is approximately four times greater than that of the human scalp and hair.
Would using a head form with a higher coefficient of friction than an actual human head be accurate in determining the effectiveness of a helmet that is designed to reduce friction between the head and the helmet?
MIPS Alternatives
There are other existing options to MIPS in regards to safeguarding against rotational impacts, some of which are recognized brands’ in-house solutions such as Kask’s WG11 rotational impact test and POC’s Spin technology. However, POC is currently transitioning to MIPS within all of its headgear.
Many helmets that are equipped with different types of safety systems get ratings that are similar to, or even better than, those of helmets that contain the MIPS technology.
An option that is offered is Bontrager’s WaveCel relevant technology, which, based on claims, can reduce rotational forces by nearly 3/4 and is 48 times more efficient in avoiding concussion when compared to helmets that don’t feature this technology.
The research conducted by Dr Steve Madey and Dr Michael Bottlang, who are the inventors of WaveCel, suggested that WaveCel offers more protection than MIPS.
According to Sam Foos from Bontrager, they have developed WaveCel- a type of foldable cellular material, which is said to be more proficient than standard foam helmets in guarding your head against harm that can happen during bicycling episodes. The process involves an alteration in the material composition of the item in three distinct steps, to absorb the rotational energy of the force of impact before it reaches your head.
Bontrager helmets with WaveCel technology have received the highest honour from Virginia Tech, according to Foos.
Bontrager chooses to utilize both WaveCel and MIPS in designing their helmets. When questioned about his choice, Foos explained that Bontrager provides a variety of items that suit cyclists’ needs by delivering the optimal combination of performance, comfort, cost, and aesthetic other considerations besides safety can
There are other considerations besides safety that can determine which technology is employed.
