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Time Trial Helmet Visor
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TOPIC: Time Trial Helmet Visor

Time Trial Helmet Visor 7 years, 7 months ago #14390

  • Dreadnought
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Some time trial helmets like the LG prologue come with a visor which presumably helps with aerodynamics. Many of the newer helmets like the Giro Advantage and the Bell Meteor II don't seem to have that option. I've seen pictures of many of the top time trialists using these helmets without the visor.

Here's my question. Does the visor make a difference. It would seem that it would make the airflow around the face less turbulent. Are there any wind tunnel tests?

Vizor 7 years, 7 months ago #14395

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At least AFM has tested a LG aero helmet with vizor vs. glasses in a tunnel. Hope he will reveal the secrets to you.

The problem seems to be with the Planet Venus effect: hot with no oxygen ) .

Cheers


A Finn

Re: Time Trial Helmet Visor 7 years, 7 months ago #14396

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i'm definitely interested too. i use a visor on my LG Rocket and it would seem much more aero, as the OP said, than with sunglasses/no visor. there's a decent sized little pocket on each side next to your eyes where i would think the helmet would act like a parachute catching the wind.

i never really seemed to have any overheating problems though because of it.

Re: Vizor 7 years, 7 months ago #14398

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A Finn wrote:
At least AFM has tested a LG aero helmet with vizor vs. glasses in a tunnel. Hope he will reveal the secrets to you.

The problem seems to be with the Planet Venus effect: hot with no oxygen ) .

Cheers


A Finn


Actually I didn't test the Rocket with and without the visor. I used my Rocket helmet (vents not taped) with visor for all the position variations and then used a Giro Advantage without visor on my best CdA positon at the end of the session. The Giro tested ~ 55 sec slower - very significant. I speculated that the visor might be part of that difference although I did note that the wind noise with the Giro (vents not taped) was noticeably greater - could not hear the test director on the microphone - so thought that most of the difference may have been related to air flow through the Giro ?? Also my sunglasses are prescription with bifocals (had to go that route to see the numbers on the SRM - getting old is not for sissy's () - the glasses probably aren't very aero as they don't wrap around so the visor probably helps with that. I haven't really noticed a problem with over heating using the visor - used it last year in Lake Los Angeles and in Arizona - both ~ 85F. Did not tape the Rocket vents.

Not sure if that helps but IMHO using a visor would seem to be of benefit ??

Re: Time Trial Helmet Visor 7 years, 7 months ago #14400

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Well...our new member Andy's test showed that the LG Rocket with the visor was just *slighltly* slower than without.

[url:29fv68xi]www.nyvelocity.com/content.php?id=1273[/url]

I'm thinking that might be "in the noise" though (no pun intended)...especially if judging by the reduction in wind noise I've noticed with the addition of a visor to my Rocket. The Rocket is a LOT quieter with the visor than without.

Actually, I'm just happy to have at least _something_ to shield my eyes...last year I wouldn't even use glasses since I'd end up looking over the tops of them anyway.

Re: Time Trial Helmet Visor 7 years, 7 months ago #14406

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not that i could build a device any better........but that rig seems like it would be full of flaws without a rider/bike, and higher windspeed.

just from the pictures of the helmets at the bottom of the screen, my guess would be that the helmets look most to least aero:
Uvex
Giro
LG
Spiuk
Rudy

though perhaps looks aren't that important, maybe that's how i got married?

Re: Time Trial Helmet Visor 7 years, 7 months ago #14413

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batesrt wrote:
i'm definitely interested too. i use a visor on my LG Rocket and it would seem much more aero, as the OP said, than with sunglasses/no visor. there's a decent sized little pocket on each side next to your eyes where i would think the helmet would act like a parachute catching the wind.

i never really seemed to have any overheating problems though because of it.


I wore a LG Rocket for the Quad Knopf. I too am stuck with prescription bifocals (Bolle ). I noticed definite "lift" pulling the helmet up when descending toward the finish line at 49 mph.

T. Field

Re: Time Trial Helmet Visor 7 years, 7 months ago #14418

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batesrt wrote:
not that i could build a device any better........but that rig seems like it would be full of flaws without a rider/bike, and higher windspeed.

just from the pictures of the helmets at the bottom of the screen, my guess would be that the helmets look most to least aero:
Uvex
Giro
LG
Spiuk
Rudy

though perhaps looks aren't that important, maybe that's how i got married?


Where would you put the LAS?
http://www.racycles.com/eq/catalog/las_ ... 733578.htm

Re: Time Trial Helmet Visor 7 years, 7 months ago #14421

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just below the Spiuk.....looks like it has a high bulge in the front part (very rounded) with a small tail that wouldn't hold airflow well. goes from real big to real small, instead of gradually reducing size.

who knows though, just a total guess opinion........

Re: Time Trial Helmet Visor 7 years, 7 months ago #14453

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I had a LG Prologue helmet.

I chanaged to a Rocket and sold the Prologue on ebay.

I kept the visor though from the rocket and I was able to fit this to the Rocket.

Re: Time Trial Helmet Visor 7 years, 7 months ago #14472

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Hello Dreadnought and All,

Using Andy's homemade test list:

Helmet with back............................Drag Grams $$

Rocket............................................109 419 170
Rocket w/ visor................................111 419 170 Plus Visor
Advantage.......................................129 310 149
Syton Open.....................................123 289 119
Spiuk Kronos...................................102 390 230
Uvex fp2.........................................107 280 253

Looks like the Uvex is the lightest if it is approved, and low drag.

For a long ride in a triathlon weight is a consideration for me as my neck gets tired and Uvex at 280 grams looks a lot better than a Rocket at 419 grams.

Also I like a visor.

But if Uvex is not approved for triathlon then is will not work.

(Weights and prices from internet and not sized or checked for reality.)

What do you think?

Cheers,

Neal

Re: Time Trial Helmet Visor 7 years, 7 months ago #14478

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i think it's a cool contraption, and better than i could do myself.........

but at the same time i think a real rider complete with body/bike would make all the difference in the world. not so much the bike, but definitely the body. the helmet would be in between two shoulders, which would drastically change the aeroflow, which would then probably drastically change the way it interacts with the helmet/back.

Re: Time Trial Helmet Visor 7 years, 7 months ago #14581

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Hello All,

Looks like helmet certification is a helmet selection qualifier for most races.

Many races seem to be revisiting the certification issue.

[url:3pip0jen]www.triathletemag.com/Departments/Traini...ts_OK_d_for_Kona.htm[/url]

A list of races and certification requirements would be helpful.

And a list of various certification standards.

[url:3pip0jen]www.bhsi.org/standard.htm[/url]

[url:3pip0jen]www.bhsi.org/stdchart.htm[/url]

[url:3pip0jen]www.usacycling.org/news/user/story.php?id=2109[/url]

Cheers,

Neal

Re: Time Trial Helmet Visor 7 years, 7 months ago #14586

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I recently sold my hookers to the guy in charge of helmets for project 96...

I asked about helmets and here was part of his reply:

All the helmets test better without the face shield...


g
wattagetraining.com

Re: Time Trial Helmet Visor 7 years, 7 months ago #14588

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gregclimbs wrote:
I recently sold my hookers to the guy in charge of helmets for project 96...

I asked about helmets and here was part of his reply:

All the helmets test better without the face shield...


g


Any speculation of why this is so??? It seems a bit counter-intuitive...

Re: Time Trial Helmet Visor 7 years, 7 months ago #14589

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i agree it's counter-intuitive, i just can't possibly imagine how a shield can't be faster.

air hits the shield and flows around my aerodynamically shaped helmet

or

that air would come right into the helmet gaps, flow over my big ears, then either trap in the helmet like a parachute, or hit the wall of foam at the back of the helmet then flow out somewhere (and where would that be since the tail should be flat on my back)?

Re: Time Trial Helmet Visor 7 years, 7 months ago #14590

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and creates funny vortexes coming off the lower edge?

dunno...

but he mentioned that removing the shield lowered the drag 30g...

he sent me a photo of the aerodyne in the tunnel...



g
wattagetraining.com

Re: Time Trial Helmet Visor 7 years, 7 months ago #14591

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gregclimbs wrote:
and creates funny vortexes coming off the lower edge?

dunno...

but he mentioned that removing the shield lowered the drag 30g...

he sent me a photo of the aerodyne in the tunnel...



g


Well...the main reason I ask is that I know with the Rocket, without the visor there's a LOT of wind noise...but with the visor, it's almost eerily quiet.

I can't imagine how air flow hitting my eye sockets and the leading edges of the ear flaps can be better than being smoothly directed around those things...then again, higher drag with the visor was seen in Andy's homemade test as well...

I wonder if the angle of the head makes any difference? My head is angled down so low, the trailing edge of the visor is almost horizontal...

BTW, what's the aerodyne?

Re: Time Trial Helmet Visor 7 years, 7 months ago #14592

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Tom_Anhalt wrote:
BTW, what's the aerodyne?




These date back to at least the '80's. Prior to the Vortex, Radius, AeroForce and Aerohead, they were the only legal aero helmet for a few years.

I think they weighed about 3lbs, and have the ventilation of a typical motorcycle helmet.

Re: Time Trial Helmet Visor 7 years, 7 months ago #14594

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Personally I don't like a visor, 'cause I sweat so much that it gets totally covered and my vision's distorted. And it's hard to reach in to wipe my eyes.

Just weighed the Garneau (437, size small) and Spiuk (397, only one size available). Don't have the other helmets here any more.

Re: Time Trial Helmet Visor 7 years, 7 months ago #14596

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T Field wrote:

I wore a LG Rocket for the Quad Knopf. I too am stuck with prescription bifocals (Bolle ). I noticed definite "lift" pulling the helmet up when descending toward the finish line at 49 mph.
T. Field


Same here. Andy's research actually persuaded me to take the visor off. There were several instances when I could feel the helmet pulling upward strongly.

I don't get that "lift" feeling when the visor is on. FWIW, the best power/speed ratios I've achieved on the local TT course have been with the visor.


-- jens

Re: Time Trial Helmet Visor 7 years, 7 months ago #14598

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Andy wrote:
Personally I don't like a visor, 'cause I sweat so much that it gets totally covered and my vision's distorted. And it's hard to reach in to wipe my eyes.


That's not a problem where I live now, with typical humidity below 15%. When I was in the Northeast, I wore a sweatband...I don't know how you people live there.

My visor died late last year anyway, so I'm glad that dovetails with this info.

Re: Time Trial Helmet Visor 7 years, 7 months ago #14601

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Andy wrote:
Personally I don't like a visor, 'cause I sweat so much that it gets totally covered and my vision's distorted. And it's hard to reach in to wipe my eyes.


I'm with you on that one - though, sometimes, if I go hard enough, even without a visor, my vision gets distorted. Is that normal!?

-kraig

Re: Time Trial Helmet Visor 7 years, 7 months ago #14605

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JV wrote:
I don't know how you people live there.

No daily constant gale force winds and there's actually some green stuff they call "vegetation" up here. You might remember it. It's a trade-off, JV.

Re: Time Trial Helmet Visor 7 years, 7 months ago #14614

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okay, so i did a little amateur science project...........

i took a small very thin dowel rod and connected some long strands of thin sewing string to the end. if you hold that in front of a powerful fan, it acts like one of the little smoke wands they use in the wind tunnel. you can see where the air goes by where the strings go.

so i tested my LG rocket with and without it on my head, with and without the visor. i think that the reason the visor is slower could be this......it seems to force air out in all directions from it, which makes the air in the helmet much lower pressure, and the air flowing around the outside of the helmet is obviously much higher pressure.

i noticed that with the visor on, the string kept wrapping around the visor and into the helmet, probably because the air naturally seeks lower pressure areas. likewise, with the helmet on my head and visor down, the strings kept flowing in and hitting me in the eyes and side of the head. so i think the air basically gets forced into the helmet anyway!

so basically without the visor, i think the majority of air still flows around the outside, but the pressure inside is closer to that of the outside, and therefore creates more constant flow.

i have to go use this on my aero bike now! try it and let me know what you come up with..................what do i win?
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