Keep in mind that helmets are designed to absorb energy. In your accident it's clear that neither you, the bike, or your helmet had much traction. So instead of tumbling (caused by rotational acceleration) you just slide. I'd expect any good helmet to absorb that energy.

The unique claim WaveCell/MIPS is making is that they can absorb the energy that's trying to rotate your head. I've seen no indications that this is a problem. Tires have great traction, pretty much anything else (you, skin, bike, backpack, helmet, bike gloves, etc) have very poor traction so accidents rarely impart large rotational forces. Even if they did the WaveCell is only going to absorb a minimal amount since the helmet is strapped to your head.

Mips and WaveCel are claiming "Rotation causes injuries", engineering a solution to it, not proving it exists, and claiming they are safer because it.

Neither MIPS or WaveCel are claiming they absorb normal impacts better than normal helmets. Generally both ANSI and SNELL have picked an acceleration and penetration standard that's a compromise between rider comfort and safety. Helmets are tested against those standards.

MIPS and WaveCel have failed to prove any additional safety and instead of working with the safety standard folks are appealing directly to consumers to justify their 3-6 times price increase over other ANSI and SNELL approved helmets.

> In your accident it's clear that neither you, the bike, or your helmet had much traction.

The impact that you can't see in the video that damaged the helmet was in the collision with the side of the truck after it hit my left arm, rotating my handlebars to the right. This caused the counter-steer that slammed me into the side of the truck. The truck was moving faster than I was, so that was the source of the rotational acceleration.

Helmets are usually worn pretty loosely, after all you don't want your jaw forced close by an overly tight helmet strap. As such you can typically move a helmet around on the top of your head, especially with say the force of a truck hitting you.

So both WaveCel and non-WaveCel helmets help absorb impacts and reduce the peak acceleration of your brain. Imparting dangerous levels of rotational acceleration seems wildly improbable. Maybe if your helmet strap got caught on the trucks lugnuts? Even then the MIPS or WaveCel would absorb maybe 30 degrees of rotation?

I'm actually curious if you still have a working WaveCel. If you try to rotate your helmet for a normal helmet how much extra rotation do you get? Is it damped as you rotate, or rotating freely within the range available?

For the Wavecel to make a difference you'd need a very high traction to allow high torque which is required to reach a high peak rotational acceleration AND a very low total rotation. Even then I'd expect a normal helmet to rotate just as far.

Antanomically I just can't see it working. I've had my chin forced into my chest, landed on the wide of my head (forcing head onto the opposite shoulder), crushed the back my helmet. But generally there's not much friction between my hair and the helmet, or the helmet and the ground. So to transfer much energy requires an impact not a shear force or torque of any kind.

Can you propose an accident that would impact a sudden large torque to a normal helmet, but a low total rotation (compatible with keeping ones head attached)? Or really anything that allows a slippery layer inside the helmet to make a meaningful difference?

If WaveCel was actually better at absorbing impacts (which they show in their animation) than styrofoam I wouldn't expect them to make their helmet out of mostly styrofoam. If the WaveCel material is worse than the helmet is actually less good at absorbing impacts than a helmet of similar thickness and weight.

Seems safest to just buy the best styrofoam helmet you can buy and don't add cost, weight, and complexity to try to offset this theorized danger of peak rotational acceleration causing concussions that is somehow mitigated by Mips or WaveCel and not by a normal helmet worn normally.

It all happens during a split second of the impact, thr helmet won't be slipping while it is being pressed against your skull by the impact, hence the slip mechanisms. The strap is to make sure your helmet is still in the right place at the moment of impact and subsequent impacts not to stop it from moving during the impact.

Whether or not it's a marketing gimmick, it's the only good indicator we have as the research is inconclusive and I certainly don't have any better idea than the people making the helmets.

That said, what I typically look to for advice on what is a safe helmet is downhill mountain biking competition standards. If they think it will make the sport safer, and their insurance lower, then it's a good indicator that it is probably a good standard to have for my own head.

That gif made my stomach sink. I've taken spills like that, but not in traffic. Super glad you walked away with only some hand fractures. Be safe, friend.

Thank you for sharing your experience and I'm glad that you are OK. I currently have a MIPS helmet and was thinking about "upgrading" to the WaveCel. The one concern I have is that the WaveCel design looks like (I can't find a local store carry them to actually try them out) it will cause a lot more sweat on my head, and I'm a pretty sweaty person. Do you find it more sweaty than traditional helmets?

Really glad to hear you're ok, and also thank you for this first hand experience.

Very glad you are ok. That video is something, made my stomach turn.

Looked at the video - the truck clipped you while overtaking?