How much drag from a helmet?

simon_masterson

This isn't a 'time trial commuting' thread or anything silly like that, but how much drag does a typical road helmet introduce? As in, in comparison to not wearing one at all, or wearing a cap (backwards, forwards, brim up, brim down)

I don't recall having seen this discussed, probably because of mandatory helmet wearing these days; I'm guessing it's been done, though? I just had the thought the other day... It would be interesting to see a similar comparison between popular helmets, too; I'm sure one of the magazines must have done that.

imposter2.0

Simon Masterson wrote:

probably because of mandatory helmet wearing these days;

:?: :?:

smoggysteve

No law saying you have to wear a helmet. Just best to with so many idiots on the road.

simon_masterson

As in mandatory helmet wearing in plenty of organised cycling events and professional races under the auspices of the UCI. I.e. the effect of wearing a helmet is irrelevant if you have no choice but to wear one to compete.

smoggysteve

Considering the rest of the person between it and the bike is as aerodynamic as a house brick I dont think it makes much difference TBH

imposter2.0

The answer you are looking for is 'minimal'. And if helmet wearing is 'mandatory' then there is no advantage or disadvantage because everyone will be wearing one regardless.

simon_masterson

SmoggySteve wrote:

Considering the rest of the person between it and the bike is as aerodynamic as a house brick I dont think it makes much difference TBH

The same could be said of most of the enhancements that time triallists make to their setup, though; and we already know that a TT-specific hat can make - albeit in TT terms - a substantial difference. Not very interesting to anyone who isn't measuring seconds, perhaps, but interesting nonetheless.

LegendLust

What's 'time trial commuting'?

Is this the latest craze that's replacing Strava?

bernithebiker

I think a normal road helmet adds quite a bit of drag. Not only does it increase the size of your head by about 50%, but they're designed to alter airflow to cool around your head.

Changing the air's speed and direction = turbulence = drag. I think it's Kask making 'filled in' helmets now to smooth the air flow. Interesting, but they are heavier, and watch out on hot days....

lawrences

Helmets are generally the 2nd change to the kit when trying to save time in a TT. Just after Aero bars and before a deep section front wheel.

simon_masterson

LegendLust wrote:

What's 'time trial commuting'?

Is this the latest craze that's replacing Strava?

It really is. All you have to do is be a gullible beginner who's started riding to work, read some articles on this site about how aero bars/TT helmets/etc make you faster, and spend away!

buckmulligan

Yes for your average rider, obviously it's the least of your worries.

But I'm surprised it's taken the pro peloton so long to see the light on this. Bike and kit manufacturers spend millions on creating aerodynamic bikes and clothing and then the rider goes and sticks a massive lump of polystyrene with a load of wind scoops in it on their head and points it headlong into the wind all day. IT'S MADNESS I TELL YOU!

The ventless helmets may look daft (especially those god-awful dome-style ones that BMC are wearing this year) but I guess for the pros it makes a significant improvement.

buckmulligan

lawrences wrote:

Helmets are generally the 2nd change to the kit when trying to save time in a TT. Just after Aero bars and before a deep section front wheel.

This article would agree with you! And also goes to show how much difference a TT helmet makes, not massive but certainly worth considering.

http://www.bikeradar.com/road/gear/arti ... ero-19273/

lawrences

BuckMulligan wrote:

lawrences wrote:

Helmets are generally the 2nd change to the kit when trying to save time in a TT. Just after Aero bars and before a deep section front wheel.

This article would agree with you! And also goes to show how much difference a TT helmet makes, not massive but certainly worth considering.

http://www.bikeradar.com/road/gear/arti ... ero-19273/

I saw a good one on some Tri site recently that had different time savings in different price brackets. Too late to search for it now and not really related to this thread but if you like article but it's quite interesting.

buckmulligan

Ok, I'll have a look for that in a sec. I like these small studies and seeing whether they back up commonly held views.

Initially I was surprised that clip-on aero bars made that much difference vs the drops, but thinking about it, your body makes up such a massive proportion of the aerodynamic drag any miniscule improvement in your position is going to outweigh a couple of piddling helmet vents.

For years I've thought that regular road helmets were woefully unaerodynamic, but it's only the last 2-3 years that I've seen the pros do anything about it (TTs excepted of course). Presumably they're all stealing DB's 'marginal gains' philosophy?!

richk

lawrences wrote:

I saw a good one on some Tri site recently that had different time savings in different price brackets. Too late to search for it now and not really related to this thread but if you like article but it's quite interesting.

this one? http://www.cyclingtips.com.au/2010/04/b ... equipment/

♠ChumBucket♠

BuckMulligan wrote:

Yes for your average rider, obviously it's the least of your worries.

But I'm surprised it's taken the pro peloton so long to see the light on this. Bike and kit manufacturers spend millions on creating aerodynamic bikes and clothing and then the rider goes and sticks a massive lump of polystyrene with a load of wind scoops in it on their head and points it headlong into the wind all day. IT'S MADNESS I TELL YOU!

The ventless helmets may look daft (especially those god-awful dome-style ones that BMC are wearing this year) but I guess for the pros it makes a significant improvement.

I was surprised to see (given these millions spent) while watching Eurosport the other day- a "pro" team rider wearing a cap under his helmet with a great big peak sticking out the front of it!! He might as well have had an umbrella stuck up there some would argue?

buckmulligan

Haha, was that Milan-San Remo perchance? That race was an exception to every rule...

Brakeless

Cancellara just won E3 Harelbeke with a cap under his helmet and the peak stickng out!

♠ChumBucket♠

Which begs the question, in general, are some people a little "aero paraniod"? :shock:

lawrences

Brakeless wrote:

Cancellara just won E3 Harelbeke with a cap under his helmet and the peak stickng out!

...and massive legs. Massive fucking legs.

Bar Shaker

I have a Giro Ionos and although it comes with a winter liner that stops the 'wind tunnel' effect cooling your head in cold weather, I wondered if a layer of cling film over the outside would make it even warmer on really cold days.

The cling film would also make it more aero, I imagine.

I have a shrink wrap machine at work but am not sure I would risk using that!

Tom Dean

♠ChumBucket♠ wrote:

I was surprised to see (given these millions spent) while watching Eurosport the other day- a "pro" team rider wearing a cap under his helmet with a great big peak sticking out the front of it!! He might as well have had an umbrella stuck up there some would argue?

Umbrellas have their uses you know.