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Scientific research has shown that the brain is particularly sensitive to rotation. For example, an oblique impact, as is usually the case when mountain biking, often leads to so-called dissections and injuries to the blood vessels. There is a risk of craniocerebral trauma. MIPS (Multi-Directional Impact Protection System) is designed to reduce rotational energy in the event of an impact by using a low-friction layer that allows the helmet to slide in a different direction to the head. This converts rotational energy into translational energy. As with a fall on ice, the head should continue to move in the original direction. So much for the theory. In reality, however, there is little resilient material available. We have conducted extensive tests to get to the bottom of how MIPS helmets work and their benefits
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MIPS - 25 years of research
In 2007, the Swedish company launched the first bicycle helmet equipped with MIPS onto the market. However, the safety system is based on 25 years of research and development. The Swedish neurosurgeon Hans van Holst began investigating the design of helmets back in 1996. He wanted to find out why so many patients were hospitalised with brain injuries even though they were wearing a helmet. Together with engineer Peter Halldin, a scientist at the Swedish Royal Institute of Technology, he realised that in most cases, a fall resulted in an oblique impact with the ground. In contrast to a frontal/straight impact, on which the design of conventional helmets is based, trauma caused by rotational forces occurs far more frequently in an oblique impact. Based on these findings, the two researchers developed a low-friction shell that would reduce the rotational forces acting on the head during a fall. MIPS was born.
Today, the rotation system can be found in well over 800 helmet models worldwide. There are now various versions of the MIPS system that allow a relative rotation between the helmet and head of 10 to 15 millimetres, which should significantly reduce the risk of concussion.
The different MIPS systems
The classic yellow low-friction layer (LFL) is still used in many current helmet models. However, the Swedes have now brought various further developments of the MIPS system onto the market. Some of the systems are so discreetly integrated into the helmet that you don't even recognise them at first glance. Here is a brief overview of the MIPS variants.
MIPS Essential Core
The classic MIPS with a yellow shell, the so-called LFL (Low Friction Layer), is used particularly in volume models (mass products) or inexpensive helmets. It is held in the helmet by small elastomers. In the test we have BrIC values (Brain Injury Criterion) measured between 6 and 26 per cent.
MIPS Evolve Core
Like Essential Core, MIPS Evolve Core sits between the helmet shell and padding. The LFL is designed to fit the helmet precisely to improve ventilation and reduce weight. Scott, Julbo and Troy Lee, for example, rely on this system, but only achieve moderately good results.
MIPS Air/Air Node
Here, the rotation protection is integrated almost invisibly into the helmet padding. This saves weight and does not impair ventilation with an additional layer. The sliding layer is located on the inside of the padding. IXS and Specialized achieved good results in the test.
MIPS Spherical/Integra Split
Bell and Giro rely on an elaborate construction that other manufacturers call Integra Split. The helmets consist of two separate shells that can be twisted against each other. The construction is complex and expensive. Both provide a good level of protection in the test.
MIPS Integra Fuse
MIPS Integra Fuse merges Poc's own SPIN system with MIPS. Here, the padding contains a type of silicone that can move in all directions. Similar to MIPS Air, the advantages are said to be low weight and good ventilation. In any case, the rotational protection is very good.
Other manufacturers have also developed their own rotation systems in the meantime. 100% calls its system SmartshockLeatt installs its so-called 360° Turbine Technology in the helmets and Kali relies on the Low Density Layer. Bontrager also has its own protection system in its programme - WaveCel. According to the manufacturers, the systems are designed to reduce the risk of concussion by up to 40 per cent.
Rotary systems from other manufacturers
Smartshock/100% Small, movable elastomers are integrated between the helmet shell and padding. The Smartshock buffers are designed to absorb shocks and dissipate the rotational energy that occurs in the event of an angled impact. On the test bench, Smartshock does not have a convincing effect.
360˚ Turbine/Leatt
Small, 360-degree movable discs made of flexible plastic on the inside of the helmet shell are designed to absorb linear impacts by up to 30 percent and reduce rotational acceleration by up to 40 percent. Compared to helmets with MIPS, the risk of concussion is significantly higher.
WaveCel/Bontrager
WaveCel is a compressible cell structure on the inside of the helmet shell. In the event of an impact, the cells bend, are then compressed like a bumper and are then designed to move to dissipate the energy away from the head. The system is below the average MIPS value.
LDL (Low Density Layer)/Kali
Like Leatt, Kali uses visco-elastic inserts on the inside of the helmet. They are designed to reduce hotspots on impact. The system is not able to deliver the advertised up to 25 per cent lower rotational forces and up to 30 per cent lower g-forces in the event of linear impacts. Compared to MIPS, the effect is rather limited.
Few independent studies on the effect of MIPS systems in helmets
As a rule, the manufacturers do not provide any proof of the effect. And the effect of MIPS can hardly be proven by independent studies. Even the TÜV cannot help here. The current test standard for helmets, EN 1078, does not include any testing of rotational forces. While a rotation test was also introduced in the motorbike sector in 2022 with ECE 22.06, an adaptation of the standard is still being discussed in the bicycle sector - the outcome is uncertain. However, researchers and developers who are discussing new test standards in the independent committees assume that a rotation test will also be anchored in the European test standard for helmets in three to four years' time. However, we didn't want to wait that long.
BIKE develops its own helmet test stand
In order to test the current generation of helmets realistically, we developed a helmet test stand ourselves in 2020 and orientated ourselves on the methods used in science and by research-based manufacturers. For the test, the helmet is fitted to an aluminium test head weighing 4.9 kilograms. During the simulated fall, the helmet and head are guided on a sled and hit a steel surface inclined at an angle of 45 degrees at a speed of 21 kilometres per hour. Sandpaper with 40 grit imitates the roughness of the surface.
This is analogous to the testing facilities at Virginia Tech, Folksam and other research institutions. The sled whizzes past the contact surface and releases the helmet, which bounces away after the impact. A six-component sensor in the test head records acceleration and rotation rates around the three axes in space on impact and in the subsequent flight phase. In the first approach, the helmet hits head-on, in the second on the side. We analyse the acceleration according to the highest resulting value - the lower the better. The average value from four measurements is given.
Risk of concussion averages 16 per cent
We convert the head rotation into a BrIC value (Brain Injury Criterion), which indicates how damaging the movement is to the brain. This method is widely used in science and allows us to make statements about the probability of a concussion using the so-called AIS code.
In our current test (BIKE 10/2023), the probability of suffering a concussion with a helmet equipped with MIPS (according to the AIS code) was around 16 per cent on average. The effectiveness of the individual systems depends heavily on how they are integrated into the helmet. In general, it is not possible to say that a particular design provides better protection than others. In the test, we measured concussion risks of between 6 and 26 per cent for the various MIPS systems.
MIPS significantly reduces the risk of concussion
In comparison, the risk for models without MIPS is 35.5 per cent in the current test. MIPS significantly reduces the risk of suffering a concussion, although this depends on the system installed. Only Bontrager's WaveCel technology delivers comparably good values with a probability of 7 per cent. The system was also convincing in the last helmet test with a probability of 15 per cent, albeit on a different model.
Rotation systems from other manufacturers with little effect
Incidentally, we were unable to confirm a positive effect of other rotation systems in the test. While the risk of a medium concussion with Smartshock was 35 per cent in the test (in 2020, the system only achieved a value of 50 per cent, also in another helmet model), 360° Turbine from Leatt is also not convincing. The value here is a very high 44 per cent. Kali was not represented in our 2023 test. However, the 2020 value of 33 per cent also suggests a significantly lower impact than MIPS.
Comparison with MIPS / without MIPS
Of course, the question of how well the MIPS system protects in direct comparison is also exciting. Some helmet models on the market are still available both with and without an additional MIPS layer. A direct comparison is therefore the best way to illustrate the effect of the Swedish safety system. To illustrate this, we tested the Lazer Impala MIPS as well as the identical model without MIPS in the BIKE 2020 test. Our experiment with the two Impala models clearly shows an improvement in the crash test values in favour of the MIPS helmet. The comparison of the IXS Trigger AM with and without MIPS also confirms this thesis. While the rotation values in the 2020 test were still 44 per cent, the use of MIPS in the 2023 test reduced the risk of concussion to just 10 per cent. A highly significant value.
Of course, MIPS does not only have advantages: On average, a helmet with MIPS costs around 25 euros more. Depending on the version used, the weight also increases by a few grams.
Lazer Impala vs Lazer Impala MIPS
At 130 euros, the Impala without MIPS 20 euros less and also saves 30 grams in weight. Otherwise, the two helmets have an identical design. The probability of suffering a moderate concussion in the event of a fall is 39 per cent, the acceleration force on impact is 109.8 g.
At the Lazer Impala MIPS The probability of suffering an average concussion is now only 26 per cent. The acceleration forces are also slightly reduced to 98.5 g. In our opinion, the thin, sliding shell inside the helmet has no negative impact on wearing comfort.
IXS Trigger AM vs. IXS Trigger AM MIPS
The difference is even clearer with the IXS Trigger. While the Helmet without MIPS has a 44 per cent probability of sustaining an average concussion, the Trigger AM with MIPS significantly better values. A reduction of just 10 per cent is enormous. The acceleration values change only slightly. While the price of the Trigger AM MIPS has been significantly increased to 189 euros, the weight has been reduced by a good 40 grams.
How does MIPS work in a helmet?
The effect of MIPS can also be visualised with a graphic from our helmet test bench. The graphic shows the measurement results of the Cube Heron (TOUR 6/2023) after a crash test. The six curves show what the six sensors in the helmet measured during an angled impact: three acceleration and three rotation values. The graph shows that the MIPS system dampens the rotation of the head to 400 °/s here. Without MIPS, we measured values of up to 1,500 °/s in the test.
Interview with Prof. Dr med. Stefan Lorenzl
BIKE: The standard sets a limit of 250 g for acceleration values for the head. What would be the consequences of such an impact?
Stefan Lorenzl: 250 times the acceleration due to gravity - that sounds like an incredible amount at first. But that can add up if you fall head-on from about one and a half metres. Without a helmet, this can be fatal. Put simply, the skull bone breaks.
The best helmets in the test are around 80 g. What about injuries?
That really is an acceptable figure. Since more and more cyclists are wearing helmets, there are significantly fewer serious and fatal injuries, especially among mountain bikers.
Wouldn't it make sense to adjust the limit value in the standard downwards?
I would definitely recommend that. We can also see that even with the current helmets, sometimes serious injuries can still occur. Particularly in road traffic, the forces at play are often quite different. Especially as the helmets are not tested for the different types of impact, but only for the linear impact.
In practice, however, the biker usually hits the surface at an angle.
Here, so-called dissections and injuries to the vessels caused by rotational forces occur much more frequently. All it takes is a quick movement backwards. The most serious consequence of this is that strokes can also occur.
How should the mode of action of MIPS be viewed from a medical perspective?
This technology is still the subject of controversial debate. So far, there are only a few good scientific studies on it, and there is often a lack of objectivity.
According to our test results, MIPS reduces the probability of an average concussion by 50 per cent on average.
Under these test conditions, the results are really interesting and the system actually seems to make sense. The values are highly significant. In research and development, risk reductions of 10 to 20 per cent would make people sit up and take notice. In any case, the range measured in the test is considerable. For me, the effectiveness seems plausible.
Conclusion - MIPS with measurable protection
Our measurements from the last two tests clearly show that MIPS can significantly reduce the damaging rotational forces on the head. However, the effect of MIPS depends heavily on the system installed and, above all, how well MIPS has been integrated into the respective helmet model. WaveCel from Bontrager is the only rotation system from another manufacturer that can keep up with the industry leader MIPS with very good values for rotation protection. According to our measurements, the other systems such as Smartshock, 360° Turbine or LDL either do not reduce dangerous forces at all or only to a very limited extent.
Even if helmets with MIPS provide better protection than models without the rotation system, no helmet can guarantee 100 per cent protection against concussions. In our eyes, however, the gain in safety is well worth the extra 10 to 15 euros for a helmet equipped with MIPS.
Stefan Frey
Editor
