i have a pecialized aurora helmet and was wondering how much you would gain by taping the vents.
well it will make you look funny thats for sure…
Gains in internal head temperature , or gains in how much sweat will pour into your eyes ?
These are COOLING vents - the more the better in my opinion, especially in a race where you are straining to the max.
A no-vent helmet is probably more aerodynamic, but won’t help you if you are “cooked” too early.
This is a bad idea. You will overheat and your day will be over before you get to T2.
At the Lifetime Fitness Triathlon, the 3rd place guy had the front 1/2 of his helmet taped with clear tape. It didn’t seem to hurt him at all on the way to the day’s 2nd fastest bike split.
You can get previous year models “real” aero helmets for less than $100 on eBay or the classifieds here.
A great investment - probably the most seconds saved per dollar out of any upgrade you can do on the bike.
My winter commuter helmet vents are duck taped inside and outside !
I’t really helps a lot keeping the head warm.
I was referring to an Ironman. In a Olympic or sprint race, it may not be an issue, but I have to wonder how much would you really save. If you are going to do it, do it in training on a real hot day then you’ll know how hot it will be.
I did before I finally coughed up for a real aero helmet. Probably almost as aero as the rest of the aero helmets. I used the temporary cellephane style winter window insulation that we use in northern climes. Blow it on with a hair dryer to shrink wrap it and it makes a nice neat job. You had to look closely to even notice the vents are covered so it was tidier than using something like packing tape. Didn’t have an overheating problem.
that has got to be the tip of the day
it is a great idea for them cooler or colder rides/races
and it is like almost free speed
Kona Express I hope you are recovering
I mised seeing you at IMLP
you are racing IMFL ???
thom
My problem is bees flying into the vents on my helmet. I have a somewhat cheap helmet and there’s no “screens” over the vents. Are there helmets with screens? I’ve never taken the time to check that out, but every long ride I end up slamming on the brakes, unclipping and pulling my helmet off before the bee can sting.
no such thing as screens on a helmet. you’re cool
well, ok, you’d have to go back to the lycra covered styrofoam days of the late 80’s/early 90’s to find them. I remember my first Giro had a mesh material over the holes back then.
i dont claim to be any kind of rocket scientist, but i’ll advise that in our visit to MIT Windtunnel, with Mark Cote, who has a great reputation for being a guru of all things aero… we tried many, many changes and the biggest drag pounds lost , for me, was going from the Spiuk to the Giro Adv II. then we taped up that cavity behind the head where the helmet comes to a tip. just ran packing tape from edge to edge in a triangle shape. and then put tape on the vent holes. so to answer your question, or atleast referring you to Mark Cote’s advise to me…those vent holes provide minimal if any real venting. they are aesthetic features for making the helmet look sporty. remember, mark is a aero maniac and is driving to find every aero gain possible…
but i wil say this, we dropped the drag about 1/2 lb of drag in total with taping the vents, and taping the cavity.
oh, and the tail 2inches off my back was far better than on my back .
the video for it can be found on our forum, www.westwoodvelo.com there is a Need for Speed thread and an MIT thread, and in there is the link to the youtube videos. i think it might be the 5th video. but i think you can hear him discussing it, and if not, you see him taping it up and the resultant change in drag.
Gains in internal head temperature , or gains in how much sweat will pour into your eyes ?
These are COOLING vents - the more the better in my opinion, especially in a race where you are straining to the max.
A no-vent helmet is probably more aerodynamic, but won’t help you if you are “cooked” too early.
Hee, hee, I think I see the super secret “behind the headtube bottle” in some of those pictures :
http://results.westwoodvelo.com/images/MIT/florida%20101.jpg
http://results.westwoodvelo.com/images/MIT/florida%20116.jpg.
can you equate what a half pound of drag means in speed over a 24 mile ride?
please dont quote me because i’m , well, a dummie…but per Zipp, i believe that negative 80grams = 10 watts. they did a study on their Zipp Clinchers which have a bulge near the rim surface. i think its actually a 404 rim molded to a disc, and that bulge really improve aerodynamics of the rear wheel. they were doing cartwheels. claiming negative 80grams of drag saving. they claimed this equated to 10watts…they then went on to say 10watts should typically equal about 40 seconds in the standard (40k, 30mph).
on analtyical cycling, (dont know exactly url here at home) they have all kinds of calculators for stuff like, if you lose X pounds of weight, how much faster will you go, further would you go…they have a calc for negative grams of drag and how that results to watts and distance.
on our site, a ver sharp fellow dave linenberg has furthered a power/cda spreadsheet. again, for me, at my weight, 10watts savings typically, if my power for a 40k TT was consistent at my FT of 350, i would realize maybe about 36 seconds or so. thats a lot.
check out our Need for Speed thread and look for Dave’s thread. might be back a few days, maybe 2 weeks or so. neat spradsheet. i presonally dont get that analytical. he’s a maniac and good at it. he just worked upa CDA spreadsheet for a TT he just won and based on his CDA that mark Cote gave him from our MIT visit, his time was within a second of estimated time. perfectly flat TT.
A few other notes from Mark: only first 1/3 of bike matters, and mark started talking about how rear wheel, disc, might not even matteer in the least. he feels only first 1/3 and top1/3 of bike matters. he was actually suggesting an 808 or 404 rear for weight savings,except for the flywheel effect, and sound/psychology, feelig fast. from an aero perspective, he felt much in the back was meaningless. then again, he’s all about aero and not really studying power or weight/power issues, just aero.
yes, that is a sneak of his bottle. very slick. with all other bottles, drag went up pretty good. with his, on some bikes was abreak even, no change…and on some, an improvement.
Thanks for taking so much time with that response. Good information.
can you equate what a half pound of drag means in speed over a 24 mile ride?
Here’s a handy “rule of thumb” for stuff like this that I stole from Andy Coggan:
0.1 lbs of drag (@ 30 mph) = 0.5 s/km = 5W = .005 m^2 of CdA
So, 0.5 lbs would equate to 2.5 s/km. 24 miles = 38.6km. So, you’re talking a savings of 38.6km x 2.5s/km = 97 seconds.
Hope that helps.
…and mark started talking about how rear wheel, disc, might not even matteer in the least. he feels only first 1/3 and top1/3 of bike matters. he was actually suggesting an 808 or 404 rear for weight savings,except for the flywheel effect, and sound/psychology, feelig fast.
Hmmm…really? Did he qualify that with any caveats about wind angle? Did you ask him if he’s ever ridden a TT WITHOUT a rear disk? Just curious 