Ok, first, some questions from the original article answered. These are from the comments section as well as other message boards.
This is possibly the worst experiment ever, there’s reasons why they use real wind tunnels…..
Wrong. The worst experiment ever would have to involve a microwave and small animals. Maybe an M80. But seriously, feel free to rip the test to shreds, just give reasons. I’m trying to learn how to do this correctly myself.
Can you do a test with the vents taped closed?
The Spiuk had 2 grams less drag with vents taped closed. (More on what that number means next week).
I showed this to my wife and explained it and she said “Huh. Why does he want to know so badly?”
Actually, I don’t really want to know so badly. I’m racing with the Spiuk no matter what. What really drives me mad are overhyped products unsupported by sound research. When I do things like this I’m hoping to catch someone in the act of making something stupid. Plus, I clearly have too much time on my hands.
@##=#<1,L>@##=#You could easily test your “finished underside” hypothesis by just taping up the underside of the Rocket. That’d be a neat thing to add to the list of data. Maybe I’d end up taping up the underside of my Rocket.
There was no change in drag when the Garneau was tested alone, with and without tape (140 grams). However, when the panel was slipped under the tail, the drag went down to 122 with tape vs 129 without tape. So it seems that taping up the underside helps, but you have to keep the tail down to reap the benefits.
Uh….how do you know the fan really goes to 22mph?
I was going by the manufacturer’s specs. Since then I got my iBike back (I loaned it out to a friend) and was able to measure the wind speed. The fan blows at about 27 mph at 6 inches. The helmets were about 8 feet from the fan, where the wind speed had decreased to 13-4 mph.
Referencing Eugene ” measure the ambient air, windchill, etc.” There is NO WIND CHILL on inanimate objects.
A probe meat thermometer (I’m such a scientist) showed no drop in temperature.
The Shootout
Now, on to the new numbers. I got my hands on a Giro, Rudy, and Uvex to add to the test. I noticed that the numbers fluctuated quite a bit from day to day, so I tried to do the test as quickly as possible while monitoring room temperature. This test took place over 2 hours on a clear day. Room temperature didn’t change, and I’m hoping humidity and barometric pressure held steady as well. I tucked the helmet straps under, to eliminate another variable. The Garneau was tested with and without a visor. The Uvex was tested only with a visor – the velcro holding it on was a little loose, and I didn’t want to damage a borrowed helmet. All helmets were run alone and with a simulated back. I tilted the styrofoam head up a bit so all the helmets could sit pretty flush to the back, which was held in the same position for all helmets. This raised the drag of the bare head a bit. On to the numbers.
@##=#<3,R>@##=#Helmet Alone
Bare Head………………………………109
Spiuk Kronos…………………………..109
Uvex fp2 ……………………………….111
Garneau Rocket……………………….111
Garneau Rocket w/ visor…………….114
Rudy Syton Open……………………..129
Giro Advantage…………………………132
Helmet with back
Kronos………………………………………102
fp2…………………………………………..107
Rocket………………………………………109
Rocket w/ visor…………………………..111
Syton Open……………………………….123
Advantage………………………………….129
Once again, some disclaimers. I’m not a scientist, nor do I play one on TV. My wind source is a joke compared to a real tunnel. I don’t know my margin of error. I’m picking out one or two gram differences in the helmets, using a scale that’s sensitive to one gram. My simulated back may or may not interact with the helmet like a real back. So be skeptical – these results may mean something, or nothing at all.
Last week I wondered if the Spiuk had 60% of the drag of the Garneau, since it added 12g of drag vs 20. Now I know that’s totally the wrong way to think about it. This week the Spiuk added 0g of drag, which would make it infinitely better than the other helmets. Of course that’s ludicrous. Next week I’ll have a full mathematical analysis of the numbers, but for now just consider these numbers a means of comparison.
@##=#<2,L>@##=#I’ve heard that the MIT tunnel says that the Garneau is slower with a visor. Interestingly, these numbers agree.
The shocker is how badly the Giro did. Given the amount of research they claim to put in, I’m almost inclined to think that this result proves my methods suck. I was surprised enough to check it against the Spiuk two more times on different days, and always got substantially more drag with the Giro.
Now, trying to understand aerodynamics intuitively is a fool’s errand, so unlike last week, I’ll not speculate on why the numbers are as they are. I’ll just post photos and let you decide for yourselves. Check back next week for the deluxe mathlete dorkface conclusion. Now if you’ll excuse me, Schmalz is going to give me a wedgie and take my lunch money.
Thanks to SBR, Anthony Accardi, Paul Goldman, and Lee3 Malone for lending their helmets.
…then its a bummer for whoever spent the big $$$ on the Giro helmet.
…then its a bummer for whoever spent the big $$$ on the Giro helmet.
Bravo! I own a Bell Meteor, wonder how it would fare?
wouldn’t you think that the speed of the wind would need to be a lot higher for the readings to be accurate? no one TT’s at 13mph (except maybe in an uphill TT when you wouldn’t need the aero bling).
nice work Andy. I gotta get some glue on the velcro strip and be more careful with how I remove the visor. Good article!
Lightly used Giro Helmet for sale….I swear this is the fastest helmet made. Decent pedigree. I have not even broke a sweat in it. All resonable offers will be considered. Would consider trading for a Spiuk Kronos or a Cervelo P3.
Mike, that could very well be the big flaw in the test. I backed the fan away hoping the airflow would be smoother and more consistent, but maybe more speed would be better.
Big snow coming. Sat morning Grant’s Tomb looks iffy. Will a go/no go decision be posted somewhere in a timely manner (i.e. like the night before so I can sleep in if cancelled)?
spoke to grant’s tomb promoter from columbia…said any cancellation will be last minute if necessary
Andy, you’ve got to mount your test rig in the bed of a pickup truck with the arm hanging out the side. Have Schmalz drive at 30mph while you take the measurements. You’ve come this far, don’t give up now!
I feel vindicated knowing that one of the most prominent scientific minds in the cycling community has once and for all put a fork in the mind-chill myth; thanks Andy. And yes Chris M., I will lighten up(loose reference to previous post). It’s spring, no more wind chills ’till next winter.
How about some hate about the Polar CS600 with Power Cycling Computer with the hubless power meter??
since size does matter….what size are the respective helmets you’ve tested? It does cloud things a little since a medium giro is the same fit as a small rocket.
since size does matter….what size are the respective helmets you’ve tested? It does cloud things a little since a medium giro is the same fit as a small rocket.
Any chance you could run a few regular road helmets (like Giro Pneumo, hint, hint) for comparison?
is there anyway to find out the wind drag specs from the manufacturers of these helmets? it would be interesting to compare against your data. i know the giro has boasted extensive wind tunnel testing and claims this is the fastest helmet of it’s type in the world.
Here’s somethng else that could be tested….
What about testing the helmets ability to disipate heat. Perhaps you could aim a small heater into the helmet with the fan on and measure tempature after X number of minutes. Maybe boiling water under them. I don’t know, you seem to know what you are doing.
These helmets aren’t aero if I have to stop at an aid station to pour water on my head.
Aid station? Long time in heat? Is this dude Tri Guy or something?
Oh intrepid Andy,
Wind tunnel testing at home,
must have, stoic wife.
These aren’t heat sinks, the heat dissapation from a bicycle helmet is the heat dissapating from evaporation due to airflow across you head. The more airflow that goes between helmet and head (rather than passing over the helmet), means the greater "heat dissapation"
The way to measure that is getting a measurement of volume of space between head and helmet (in cm3), and then measuring the airspeed within the helmet (kmph)then you get a volume displacement per time period.
Why are you guys so hung up on testing things with thermometers. Do you miss mercury poisoning?
You can measure heat dissipation using the wind-chill formula! Set up the rig and ask the dummy head how he "feels" under the different conditions. Rate his feelings according to Bernoulli Real-Feel index, insert that value into the wind-chill formula, and voila!
It works every time!
the people with thor mancrushes needed more inspiration, you just had to post a link to that picture.
"This test took place over 2 hours on a clear day. "
Did you get grounded again?
Dammit Eugene! I swore off wind chills ’till next winter and now we’re back at it again! Of course this time you’re right on; I’ll leave heat index’s, Bernoulli Real Feels, and the likes to our resident mad scientist. Also, if you need a "dummy head" that can report back perceived exertion, etc. ; look me up at Central Park Sunday in the 3/4, I’m pretty sure I’ll qualify.
What about the Bell Meteor? It certainly appears to be the bomb, and, as any self-respecting masters racer knows, it’s all about how pro you look. Something about the inverse relationship between disposable income and physical ability.
What about the Bell Meteor? It certainly appears to be the bomb, and, as any self-respecting masters racer knows, it’s all about how pro you look. Something about the inverse relationship between disposable income and physical ability.
What about the Bell Meteor? It certainly appears to be the bomb, and, as any self-respecting masters racer knows, it’s all about how pro you look. Something about the inverse relationship between disposable income and physical ability.
What about the Bell Meteor? It certainly appears to be the bomb, and, as any self-respecting masters racer knows, it’s all about how pro you look. Something about the inverse relationship between disposable income and physical ability.
What about the Bell Meteor? It certainly appears to be the bomb, and, as any self-respecting masters racer knows, it’s all about how pro you look. Something about the inverse relationship between disposable income and physical ability.
What about the Bell Meteor? It certainly appears to be the bomb, and, as any self-respecting masters racer knows, it’s all about how pro you look. Something about the inverse relationship between disposable income and physical ability.
yeah, i really wanted to make my point – doh. Problem with the post not appearing and thinking it did not go through. Sorry about the repeat posts.
Maybe a problem with that inverse relationship between age and computing abilities?
nah, i’ve always been stupid
that’s pro as shit!
Hey, if you wear ten of those helmets you can go backwards in time!
I just checked the price of these things and ils sont tres, tres cher! A lot of dough for a sucky master rider to shell out for one or two time trials a year. . . is there any other practical application for these things that you can think of? I wonder what happens when you swim laps in that Spiuk?
One possible alternative to buying one of these would be to just subtract the "advantage" from one’s time with a normal helmet. Is there any accepted percentage figure for the time reduction you’d get from wearing one of the better tear-drop helmets (assuming clip-on aero bars and pretty good position)?
I just clicked on to your site from little old fashioned England. You guys sure do get into things deep.
As a 74 yrs old master I just get on and ride, maybe thats why I don’t win
we’re obviously very prone to wretched excess on this side of the pond. we love to obsess and sublimate as our culture unravels around us, but we do ride sometimes. . . although all my friends who’ve ridden in England come home saying they’ve had their asses kicked.
Note to England:
Last weekend’s racing was cancelled due to snow, the Spring fashions haven’t arrived yet, and our military haven’t bombed any small brown people recently. We need some entertainment.
Excellent link, thank you! Check the next installment for analysis, coming up 3/22.
I think that hits on the big limitations with the test–the lack of a real back, the straight neck, and both of those problems combining to give you the wrong helmet angle. I was watching a pro TT the other day and they all have the tail much higher than it looks like you do. Hard to tell from the photos.
says when he won final TT stage of 1989 TdF
his aero bars gained eight seconds
his aero helmet lost fifteen seconds
when he raised his head to look at the road,
or lowered his head to look at his pedaling,
it was drag he lost in those precious seconds.
this way he beat Fignon nonetheless.
Andy, I like the way you think. This reminds me of the show ‘Mythbusters’. I don’t think getting the fan closer to get a higher windspeed will change the relative results. Yes, the drag will be higher, but all the helmets will end up in the same relative position to each other. If you have the time you may want to build a wind tunnel using some thin cardboard. Tape the front around the fan and then leave the back open. Make a slot in the side just long enough for the arm supporting the helmet can move. You then have your own mini wind tunnel. The nice thing about this is that you can then use the same set up to test other small objects. You may even want to consider a fairing, again made out of cardboard, to put onto the supporting arm. But that is not that important since the drag on the arm will be the same for all the items you test. Another item to consider is getting a lamp dimmer. You could then plug the fan into the dimmer and use it to regulate fan speed. You could then use your wind meter to check fan speed. All your tests could be performed at known windspeeds on different days. Then you could compare results on different days. The only varialble would be humidity. Not sure how you would control that. I’m sure this set up would give you repeatable results, which is what is important. Nice job!
why not just pay to get tested at a real wind tunnel? seems like less work …
$1000/hr, that’s why. Well, that and I have a DIY mentality.
$1000/hr, that’s why. Well, that and I have a DIY mentality.
why not just pay to get tested at a real wind tunnel? seems like less work …
Andy, I like the way you think. This reminds me of the show ‘Mythbusters’. I don’t think getting the fan closer to get a higher windspeed will change the relative results. Yes, the drag will be higher, but all the helmets will end up in the same relative position to each other. If you have the time you may want to build a wind tunnel using some thin cardboard. Tape the front around the fan and then leave the back open. Make a slot in the side just long enough for the arm supporting the helmet can move. You then have your own mini wind tunnel. The nice thing about this is that you can then use the same set up to test other small objects. You may even want to consider a fairing, again made out of cardboard, to put onto the supporting arm. But that is not that important since the drag on the arm will be the same for all the items you test. Another item to consider is getting a lamp dimmer. You could then plug the fan into the dimmer and use it to regulate fan speed. You could then use your wind meter to check fan speed. All your tests could be performed at known windspeeds on different days. Then you could compare results on different days. The only varialble would be humidity. Not sure how you would control that. I’m sure this set up would give you repeatable results, which is what is important. Nice job!
says when he won final TT stage of 1989 TdF
his aero bars gained eight seconds
his aero helmet lost fifteen seconds
when he raised his head to look at the road,
or lowered his head to look at his pedaling,
it was drag he lost in those precious seconds.
this way he beat Fignon nonetheless.
Excellent link, thank you! Check the next installment for analysis, coming up 3/22.
I think that hits on the big limitations with the test–the lack of a real back, the straight neck, and both of those problems combining to give you the wrong helmet angle. I was watching a pro TT the other day and they all have the tail much higher than it looks like you do. Hard to tell from the photos.
Note to England:
Last weekend’s racing was cancelled due to snow, the Spring fashions haven’t arrived yet, and our military haven’t bombed any small brown people recently. We need some entertainment.
we’re obviously very prone to wretched excess on this side of the pond. we love to obsess and sublimate as our culture unravels around us, but we do ride sometimes. . . although all my friends who’ve ridden in England come home saying they’ve had their asses kicked.
I just clicked on to your site from little old fashioned England. You guys sure do get into things deep.
As a 74 yrs old master I just get on and ride, maybe thats why I don’t win
that’s pro as shit!
Hey, if you wear ten of those helmets you can go backwards in time!
I just checked the price of these things and ils sont tres, tres cher! A lot of dough for a sucky master rider to shell out for one or two time trials a year. . . is there any other practical application for these things that you can think of? I wonder what happens when you swim laps in that Spiuk?
One possible alternative to buying one of these would be to just subtract the "advantage" from one’s time with a normal helmet. Is there any accepted percentage figure for the time reduction you’d get from wearing one of the better tear-drop helmets (assuming clip-on aero bars and pretty good position)?
nah, i’ve always been stupid
Maybe a problem with that inverse relationship between age and computing abilities?
What about the Bell Meteor? It certainly appears to be the bomb, and, as any self-respecting masters racer knows, it’s all about how pro you look. Something about the inverse relationship between disposable income and physical ability.
yeah, i really wanted to make my point – doh. Problem with the post not appearing and thinking it did not go through. Sorry about the repeat posts.
What about the Bell Meteor? It certainly appears to be the bomb, and, as any self-respecting masters racer knows, it’s all about how pro you look. Something about the inverse relationship between disposable income and physical ability.
What about the Bell Meteor? It certainly appears to be the bomb, and, as any self-respecting masters racer knows, it’s all about how pro you look. Something about the inverse relationship between disposable income and physical ability.
What about the Bell Meteor? It certainly appears to be the bomb, and, as any self-respecting masters racer knows, it’s all about how pro you look. Something about the inverse relationship between disposable income and physical ability.
What about the Bell Meteor? It certainly appears to be the bomb, and, as any self-respecting masters racer knows, it’s all about how pro you look. Something about the inverse relationship between disposable income and physical ability.
What about the Bell Meteor? It certainly appears to be the bomb, and, as any self-respecting masters racer knows, it’s all about how pro you look. Something about the inverse relationship between disposable income and physical ability.
"This test took place over 2 hours on a clear day. "
Did you get grounded again?
Dammit Eugene! I swore off wind chills ’till next winter and now we’re back at it again! Of course this time you’re right on; I’ll leave heat index’s, Bernoulli Real Feels, and the likes to our resident mad scientist. Also, if you need a "dummy head" that can report back perceived exertion, etc. ; look me up at Central Park Sunday in the 3/4, I’m pretty sure I’ll qualify.
the people with thor mancrushes needed more inspiration, you just had to post a link to that picture.
You can measure heat dissipation using the wind-chill formula! Set up the rig and ask the dummy head how he "feels" under the different conditions. Rate his feelings according to Bernoulli Real-Feel index, insert that value into the wind-chill formula, and voila!
It works every time!
These aren’t heat sinks, the heat dissapation from a bicycle helmet is the heat dissapating from evaporation due to airflow across you head. The more airflow that goes between helmet and head (rather than passing over the helmet), means the greater "heat dissapation"
The way to measure that is getting a measurement of volume of space between head and helmet (in cm3), and then measuring the airspeed within the helmet (kmph)then you get a volume displacement per time period.
Why are you guys so hung up on testing things with thermometers. Do you miss mercury poisoning?
Aid station? Long time in heat? Is this dude Tri Guy or something?
Oh intrepid Andy,
Wind tunnel testing at home,
must have, stoic wife.
Here’s somethng else that could be tested….
What about testing the helmets ability to disipate heat. Perhaps you could aim a small heater into the helmet with the fan on and measure tempature after X number of minutes. Maybe boiling water under them. I don’t know, you seem to know what you are doing.
These helmets aren’t aero if I have to stop at an aid station to pour water on my head.
is there anyway to find out the wind drag specs from the manufacturers of these helmets? it would be interesting to compare against your data. i know the giro has boasted extensive wind tunnel testing and claims this is the fastest helmet of it’s type in the world.
Any chance you could run a few regular road helmets (like Giro Pneumo, hint, hint) for comparison?
since size does matter….what size are the respective helmets you’ve tested? It does cloud things a little since a medium giro is the same fit as a small rocket.
I feel vindicated knowing that one of the most prominent scientific minds in the cycling community has once and for all put a fork in the mind-chill myth; thanks Andy. And yes Chris M., I will lighten up(loose reference to previous post). It’s spring, no more wind chills ’till next winter.
How about some hate about the Polar CS600 with Power Cycling Computer with the hubless power meter??
since size does matter….what size are the respective helmets you’ve tested? It does cloud things a little since a medium giro is the same fit as a small rocket.
spoke to grant’s tomb promoter from columbia…said any cancellation will be last minute if necessary
Andy, you’ve got to mount your test rig in the bed of a pickup truck with the arm hanging out the side. Have Schmalz drive at 30mph while you take the measurements. You’ve come this far, don’t give up now!
Big snow coming. Sat morning Grant’s Tomb looks iffy. Will a go/no go decision be posted somewhere in a timely manner (i.e. like the night before so I can sleep in if cancelled)?
Mike, that could very well be the big flaw in the test. I backed the fan away hoping the airflow would be smoother and more consistent, but maybe more speed would be better.
nice work Andy. I gotta get some glue on the velcro strip and be more careful with how I remove the visor. Good article!
Lightly used Giro Helmet for sale….I swear this is the fastest helmet made. Decent pedigree. I have not even broke a sweat in it. All resonable offers will be considered. Would consider trading for a Spiuk Kronos or a Cervelo P3.
wouldn’t you think that the speed of the wind would need to be a lot higher for the readings to be accurate? no one TT’s at 13mph (except maybe in an uphill TT when you wouldn’t need the aero bling).
Bravo! I own a Bell Meteor, wonder how it would fare?
…then its a bummer for whoever spent the big $$$ on the Giro helmet.
…then its a bummer for whoever spent the big $$$ on the Giro helmet.