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SubscribeSpiuk Kronos Hate
Wed, 03/07/2007 - 1:00am by alex
I wanted to review Spiuk's new, very flash TT helmet, the Kronos. But, absent wind tunnel data, all I could've done was yammer on about how pretty it is and how it makes me a total chick magnet. Or maybe I could've written a thousand word essay about my taint, but apparently I'm more reticent than some people. So I did what any reasonable person would do: I built a rig to measure the drag of TT helmets. (Full disclosure: Spiuk is a team sponsor, so I was sorta hoping the helmet would do well.) (Full disclosure 2: measuring TT helmet drag doesn't make you a chick magnet.)
I know, I know, my place is a mess.
The rig is built around an old wheel. A crossbar is attached to the wheel, which is mounted in a workstand laid on its side. The wheel's there just for its bearings. A styrofoam head is attached to one end of the crossbar. Monofilament is wound around the rim, then goes over a hub acting as a pulley, and a basket is hooked to the end. The crossbar only rotates a few degrees. When the forces balance and the crossbar teeters 3-5 millimeters from one of its stops the basket is removed and weighed. I rented a fan that blows up to 22 mph, reasoning that the greater the drag force, the more the rig's friction would be negated. The rig turned out to be amazingly sensitive – a mere 1.5 gram washer could make the crossbar move.
Of course, the setup is flawed. Even though the channel of air is pretty focused (about 2' in diameter), it still blows on parts of the rig, adding to the total drag. The airflow is certainly less consistent than real world conditions. The foam head is smaller than a typical head, and the whole thing isn't attached to a body or a bike. So take these results with a grain of salt.
I ran tests with the Kronos, my Garneau Rocket, my Spiuk Nexion (a regular helmet), and the head alone. Each was run three times and averaged. The numbers are meaningless in absolute terms.
Kronos.....................120g
Rocket.....................128g
Nexion.....................178g
Bare Head................108g
The bare head number might seem low, but as stated earlier, the foam head is small. I took frontal shots of my disturbingly pointy head next to it and found that my head's about 1.2 times bigger. And since drag increases in direct proportion to frontal area (I'm assuming the two heads have the same coefficient of drag), my disembodied head would have registered about 130 grams (or less, depending on how much the crossbar is adding to the total drag). Assuming that number is accurate, then these TT helmets are faster than a bare head (you listening, Mr. Fignon?). I'm sure one of those slim illegal fairings (that don't offer protection) would be even faster. And of course, a TT helmet is much faster than a regular helmet.
If you read the data as 'how much drag does the helmet add to the base rig', you get the Kronos with 12g, Rocket 20g, Nexion 70g. Interpreting the data this way would mean that the Kronos has 60% of the drag of the Rocket. I'm not positive this is the correct way to read the data, but if so it's quite surprising. I suspect the Spiuk's closed bottom has something to do with this.
Next I added a flat panel under the helmet to simulate a back. Would the Rocket lose its disadvantage if its open bottom sat flush against a back? I did runs with the helmets as close to the panel as possible, and with the helmet tails 3" off the panel. Once again, three runs each.
Kronos flush.....................112g
Kronos raised 3"...............121g
Rocket flush.....................128g
Rocket raised 3"...............130g
Bare head........................106g
This was pretty surprising. The Spiuk got a bigger boost by sitting flush against the 'back', while the Garneau basically saw little or no change. I have no clue as to why this is, but I do know that you better not drop your head and let that helmet come off your back.
Time for Hate
Well, it's $230. But it is pretty and fast.
Where does that leave us?
I'll try to amass more helmets and do more testing. In fact, if you're in the NY area and have a LAS, Rudy, Bell, or Uvex (I have a Giro lined up already), drop me a line using the 'info' link in the top banner. I'll also try to get in some other dumbass pseudoscience experiments – saran wrapped helmets, shoe covers, mankinis, whatever.
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Comments
Add a commentJust happened on this while looking for reviews on aero helmets... wicked cool idea. Who cares about 100% scientific validity in terms of conditions, you did an A vs. B vs. C test in like conditions, and the results stand. Thanks for posting this.
saved a few steps if you just had the other end of your moment arm press into the scale to measure the drag force... instead of fishing line.
There are some things in life that should be left to the professionals, for example brain surgery and incompressible aerodynamics. The work here should be applauded for the innovative efforts, but the test conditions (too small of flow area, flow not properly simulated since the body of the rider is not included, incorrect incoming turbulence levels from a house fan, etc etc) are so poorly simulated that the results are highly suspect. In fact, they may lead to totally false conclusions.
Jesus, Captain Ed, cant you just hear the snarky sarcastic tone as Eugene wrote that?...lighten up my man!
Referencing Eugene " measure the ambient air, windchill, etc." There is NO WIND CHILL on inanimate objects. Didn't we put this myth to bed a coupla weeks ago? Andy, please do the world a favor. You obviously have a very scientific mind ( and way too much time on your hands), measure the air temperature in the room and the air coming off the fan. Prove to the uneducated masses once and for all that the temperature will be the same with the possible addition of a little motor heat. And by the way how much time can I shave off my 1:07 40k TT with the Spiuk?
ping pong at Andy's house:
video.google.com/videoplay?docid=-8079411349144989883
Truly frightening.
schmalz...I belly laughed out loud when i read you road runner comment...
andy...nice test, but more importantly: when is the ping pong tournament?
Can you do a test with the vents taped closed?
You've told shared this mind-boggling info with "Kramer" and his recently converted teammate, F-bomb, right? They'll be creaming over it. Nice work, Andy.
Anyone know the details of the CRCA TT races? individual/3 men, place etc etc.
I felt faster in the ML kit... LOL...
Could you try tapping the openings closed on the Spiuk?
"how do you know the fan really goes to 22mph?"
Put a thermometer in front of it and measure the difference from the ambient air temperature. Insert that temperature difference into the wind-chill formula, and voila!
And if it doesn't work, then something must be wrong....
The other cycling web sites should just quit now, NYVC is in a league of its own now..
Uh....how do you know the fan really goes to 22mph?
Now is the time for Andy's friends to gather for an intervention. This is a cry for help if I've ever seen one...
I wonder why the Spiuk has a mesh covered vent on the tail. Once a bee gets in my bonnet, I want to give it a way out!
Alls I can say is.. NO YOU DIDNT!
just awsome...
You have completely lost your mind. There's no turning back, Andy.
Andy you are my hero, not only do you come up with these fantastic homemade testing devices, but you have figured out a way to convince your signficant other that this is an ok use of your time. How do you do it?
but do you think it works with our kit?
This is genius, mad genius. You can make it up to your wife by sending the styrofoam man out with a camera to shoot the races while you sleep in.
I perform a service. Oh my poor wife.
I can show it too my wife and say "See honey, you could have it a lot worse"
This is possibly the worst experiment ever, theres reasons why they use real wind tunnels.....
You're my new hero. I've done some whacky experiments at home, and I've seen some cool rigs, but this one is probably the best I've seen.
There is a wig store somewhere in Manhattan wondering what happened to their display... Dude, this is the trippiest experiment you have done yet - even better than the cat bike in terms of mechanical genius... NICE!
This reminds me of that breakfast machine that I made in my playhouse. Huh HUH
Wind tunnel? We don't need no stinking wind tunnel!
if it had nothing to do with time trialing
i'll be by later on for TT positioning. you're going to need a bigger basket.
Mr. Goldberg would be proud.
Where exactly in this whole contraption is the spot to put the bird feed to catch the Road Runner with?
pretty sure this doesn't count as "using your powers for good," but at least you aren't using them for evil. ...did you win your high school science fair?
saved a few steps if you just had the other end of your moment arm press into the scale to measure the drag force... instead of fishing line.
There are some things in life that should be left to the professionals, for example brain surgery and incompressible aerodynamics. The work here should be applauded for the innovative efforts, but the test conditions (too small of flow area, flow not properly simulated since the body of the rider is not included, incorrect incoming turbulence levels from a house fan, etc etc) are so poorly simulated that the results are highly suspect. In fact, they may lead to totally false conclusions.
Jesus, Captain Ed, cant you just hear the snarky sarcastic tone as Eugene wrote that?...lighten up my man!
Referencing Eugene " measure the ambient air, windchill, etc." There is NO WIND CHILL on inanimate objects. Didn't we put this myth to bed a coupla weeks ago? Andy, please do the world a favor. You obviously have a very scientific mind ( and way too much time on your hands), measure the air temperature in the room and the air coming off the fan. Prove to the uneducated masses once and for all that the temperature will be the same with the possible addition of a little motor heat. And by the way how much time can I shave off my 1:07 40k TT with the Spiuk?
ping pong at Andy's house:
video.google.com/videoplay?docid=-8079411349144989883
Truly frightening.
schmalz...I belly laughed out loud when i read you road runner comment...
andy...nice test, but more importantly: when is the ping pong tournament?
Can you do a test with the vents taped closed?
You've told shared this mind-boggling info with "Kramer" and his recently converted teammate, F-bomb, right? They'll be creaming over it. Nice work, Andy.
Anyone know the details of the CRCA TT races? individual/3 men, place etc etc.
I felt faster in the ML kit... LOL...
Could you try tapping the openings closed on the Spiuk?
"how do you know the fan really goes to 22mph?"
Put a thermometer in front of it and measure the difference from the ambient air temperature. Insert that temperature difference into the wind-chill formula, and voila!
And if it doesn't work, then something must be wrong....
The other cycling web sites should just quit now, NYVC is in a league of its own now..
Uh....how do you know the fan really goes to 22mph?
Now is the time for Andy's friends to gather for an intervention. This is a cry for help if I've ever seen one...
I wonder why the Spiuk has a mesh covered vent on the tail. Once a bee gets in my bonnet, I want to give it a way out!
Alls I can say is.. NO YOU DIDNT!
just awsome...
You have completely lost your mind. There's no turning back, Andy.
Andy you are my hero, not only do you come up with these fantastic homemade testing devices, but you have figured out a way to convince your signficant other that this is an ok use of your time. How do you do it?
but do you think it works with our kit?
This is genius, mad genius. You can make it up to your wife by sending the styrofoam man out with a camera to shoot the races while you sleep in.
I perform a service. Oh my poor wife.
I can show it too my wife and say "See honey, you could have it a lot worse"
This is possibly the worst experiment ever, theres reasons why they use real wind tunnels.....
You're my new hero. I've done some whacky experiments at home, and I've seen some cool rigs, but this one is probably the best I've seen.
There is a wig store somewhere in Manhattan wondering what happened to their display... Dude, this is the trippiest experiment you have done yet - even better than the cat bike in terms of mechanical genius... NICE!
This reminds me of that breakfast machine that I made in my playhouse. Huh HUH
Wind tunnel? We don't need no stinking wind tunnel!
if it had nothing to do with time trialing
i'll be by later on for TT positioning. you're going to need a bigger basket.
Mr. Goldberg would be proud.
Where exactly in this whole contraption is the spot to put the bird feed to catch the Road Runner with?
pretty sure this doesn't count as "using your powers for good," but at least you aren't using them for evil. ...did you win your high school science fair?
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