A couple of things. Re the Kask aero visor creating a bubble of circulating but static air the the main airflow goes around, this is a well known phenomenon with pick up trucks. The argument was whether you got better fuel efficiency with the tailgate up or down. Experiments ahowed that with the tailgate up, a bubble of recirculating air is created in the bed when the truck is moving, and the recirculating air bubble helps direct the airflow smoothly over the back of the truck, decreasing drag. Dropping the tailgate cause the recirculating air bubble to collapse and increases drag. The television show Mythbusters did a segment on it. It appears Kask has recreated the effect on a small scale and fools the air into thinking the helmet is wider than it is. On the Specialized TT5, I wonder if the flat portion at the back is effectively like the truncated teardrop shape you mentioned that we've seen on frames for some time.

This is so great. LOVE hearing how passionate (won't say nerdy 😃 ) you are about this. So interesting to see you break down how you think it's faster. Your insert shot about the Kask visor was very cool to hear - your curiosity and explanation. Love it.

Confusing why manufacturers continue to release these helmets without a public video explaining the design engineering

It's so beautiful this series of videos

When the explanation requires "counter-rotating vortices", I'll just take your word for it 🤣

Brilliant point about helmets being made for specific people.

Can you do an aero test between having a hole in your socks and fully intact socks 🧦

It strikes me that the flaps on the Kask are a similar in principle to car air curtains which are used to reduce a car’s drag by directing air around the turbulent areas of the wheel wells. It’s actually quite a sound theory, proven by the fact that it’s transferable to many models of car.

Great insight once more, Alex. So glad to see the swim hat get a shout out, even if it is hidden under the helmet. Still, could save a second for triathletes to leave it on through transition and a couple of seconds on the ride, with their helmet over the top. Maybe we could get a triathlete to test it?

Another guess on the flat part of the TT5: that matches Remco's (or our) back, so the top of the helmet doesnt stick out in front of the torso. I thought about this when you mentioned that the helmet was designed for him. I'm totally unqualified for aerodynamics, but love reducing my drag.

I was about to comment here that the Kask visor flaps were not a redirector until 13 mins into this video (they wouldn't be at that angle or height) but were instead to create pressure changes to help the air over the shoulders. Your homework and intuition on Gurney flaps was spot on Alex. However, they won't help most of us amateurs because we don't possess a high enough velocity to make them work. In fact, most of the pro's won't either. Best wishes, Bryce.

great idea doing the test on higher speed for the flaps. I would love to see more test whith lots more different speeds. like 25-30-35-40-45-50-55-60-65-70 as TTs arent allways flat we have lots of different speeds.

Get Dan Bigham on the channel, please! He could probably explain a lot of these things in detail (if he is allowed to speak freely). Also, Remco started using a shorter version of the visor for the TT5 helmet.

Any ducting inside the Kask? I would be curious to see if they are trying to move air to vent out the gap/slot you showed in your previous video behind the gurney flap. With regards to the Specialized, I think the idea is to provide an outlet for the high pressure area created in front of the shoulders. In a lot of Remco TT photos the back of the helmet is flush with his back but then you get a nice little gap between the rear edge of the shark fin and the collarbone. Some clean air gets pulled up through the visor gap you noted then moves around the smooth head/sock and out the rear duct. With right shape you might get a nice venturi which would then also pull air in through the gap between the shoulder and the shark fin, reducing pressure. Entire video series has been fascinating, BTW.

Your graphic illustration at 6:41 reminds me of the new giro - long at both front and back (as opposed to traditional tear drop which is only long at back and being most helmet designs)

From the testing I’ve been apart of with both track and road teams the Kask visor tends to work more on women due, the engineers seem to think it increases air flow attachment around the hips but equally everyone is aerodynamically unique

Interesting - very interesting. Once you see Ganna's (oh so perfect) head position vs yours in that helmet - in the Tunnel, and your explanation, I can see why you might be getting the results you were.

I notice a small clip of metal at the back of the POC. Is that there to make sure that you can feel that the back of helmet is on your upper back?

it is a vortex generator, you see them on the roof of some cars and on the wings of some planes. It adds a little bit of momentum to the oncoming air so that there will be less of a pressure difference when the air gets to the back, and this translates to less total drag

Soinds like the kask flap would work well on yhe track too with the higher speeds. Interestingly i had a quick look and Ganna wears it for his pursuits, but Bigham wears the older helmet but also rides with a drastically different head position. Very obvious in their worlds race against each other

when you talk about the flaps, I can't help but think of F1 aero dynamics... like the way they use floor edge designs to seal the underside of the floor. Basically using a small separated body of air to manipulate an adjacent body of air. It would've been cool to use that smoke wand thingie in the wind tunnel when testing the helmets to give us a look at how the air flows... next time?...

So for track sprinting, the aero visor could possibly be an advantage, as we often travel in excess of 60km/h? My helmet of choice is the Bambino Pro, which uses the same visor as the Mistral.

I'm really excited what you have found on the HJC, Aerohead and POC Procen. Will there also about a Video about them? Looking for an "alround" Helmet for Triathlon.

I guess you could have used flow visualisation like smoke coming out of a long tube, then you might have been able to see the vortices being generated by the Kask visor

Please do a road helmet like the poc ventral with and without a cycling cap underneath

Hey Alex, please give us your thoughts on MIPS, the helmet safety technology. I heard pros remove this from helmets to get a snugger fit, justified by MIPS being less effective in crashes at higher speeds. I have no idea if any of that is true. The skeptic in me says MIPS is half-scam and a nice excuse to charge more for helmets.

I wonder about the utility of a TT air speed optimised skull cap under any of these helmets with in helmet airflow. I'd assume you'd get significantly better performance with the sort of materials used in say aero socks or the shoulders of a speedsuit rather than a hydrodynamic optimised swim cap. Could be a growth market for say nopinz or huub, especially given the UCI banning the integrated balaclava

In diving the splashing off the surface is for the diver to better see the surface and judge his entry point it has nothing to do with à better or softer entry Btw love the nerdy aero séries keep the good work up Alex

Back in the early 1990s Johnathon Vaughters and Colby Pierce tried wearing pantyhose over their heads under their helmets for TTs. It had the effect of smoothing out the hair and ears, just like the Specialized snood. I have no idea where that idea came from, but it isn’t totally new. Colby worked with John Cobb (the inventor of the split nose saddle) quite a bit around that time and that guy came up with some really innovative stuff. For example, his Blackwell Engineering wheels were the first wheels I am aware of used the blunt inner edge.

So here's a question. If we know the aero sock in the TT5 is faster, and the UCI is going to ban it, is there a rule that would prevent a rider wearing a skinsuit with a hood like those used in speed skating? Should do the same thing as the aero sock... maybe even better... and it's not part of the helmet, so the UCI can't rule against it as "non-essential" to the helmet (although that doesn't mean they wouldn't find some other rule.) Of course, overheating would likely be an issue.

why does Remco run a shorter visor on the tt-5 helmet?

Is that a magnet on the POC tempor?

Something I wanted to point out: at least since TT worlds, Remco has been using an unreleased short visor with the edge above his nose, unlike the stock visor that extends below. I think it might lend credibility to the idea that the Specialized helmet in-part relies on airflow inside the helmet in the lower half.

So that’s what the fast men of yesteryear were wearing.. all those pics of Martin Pyne et al in balaclavas, the only thing missing was an aero helmet

I believe Ganna is using the Bambino pro though, not the Mistral.

You know you’ve made it when a production helmet is specifically designed to to for your shoulders and body position

As the integrated balaclava of the Specialized is banned, riders can use balaclavas which are made for Kart sports.

Now they've banned the head sock on the Specialized, what's stopping someone rocking up to their next TT with a cut out pair of tights on their head? I already wear a headband for the purpose of catching sweat during a TT, so why not just go the whole hog and cover the whole head?

Dowsett, radio holder or magnet on the tail of the tempor? (7:44 in)

I don't think they designed that specialized helmet specifically for Remco. They have decades of research. The bike and all the equipment presented in the WIN tunnel is all Specialized so they can focus on keeping all principles the same and only change out one element like the helmet to see the change. They also have triathletes, now Roglic and a consumer base to market the helmet to. It isn't just one rider in particular. The Kask flap, I thought it was for the larger riders like Ganna and Tarling? Everyone else is too small to take advantage of a device like that.

To me the specialised helmet looks like a cam tail itself. That's why its flat at the back.

Mmmmm Did wiggins lamb chops as a gurney flap deflector, or Ashton Lambie hirsute top lip, Quinn simmons full beard acting like a bladder....always something else to test. keep it up

"Flaps are now being played with"

Does Remco have a severely oval head shape? 🤣I love Specialized helmets, but man, they are made for seriously narrow heads. I always get the Asian fit, but even that is more narrow than a lot of helmets.

If you are not a person with expertise on Tt bikes and equipment I am a lemur….

homie needs a shower