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Re: Giro Aerohead [jeffp] [ In reply to ]
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jeffp wrote:
the watts for the rider listed are really a red herring. if the helmet reduces drag by X amount at Y speed, the things that are relevant are the X and the Y, not the Z power output as the rest of the rider/bike system might be assumed to remain unchanged. Give that the number posted make no sense on the Giro site, ie 1g reduction = 1w means they either need to correct their data or tel us why they are testing at 50 mph instead of 30mph(or whatever speed they are testing at , as it is not listed on the site) While Jim may be giving good insight, the giro site really looks like bad marketing spin that was not checked before uploading to the interwebs


There REALLY needs to be an insistence on drag values and differences being reported in terms of CdA (and in m^2...I'm looking at YOU, A2). They can still do all of the calculations for time and power for various speeds, but at least report the most universally useful value. It's not that hard :-/

http://bikeblather.blogspot.com/
Last edited by: Tom A.: May 20, 16 8:10
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Re: Giro Aerohead [pyrahna] [ In reply to ]
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pyrahna wrote:
Surface area or frontal area?

Frontal.
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Re: Giro Aerohead [Tom A.] [ In reply to ]
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I agree there needs to be a standard reporting metric. And I agree with the way you want to do it. On the other hand asking marketing people and the average athlete to comprehend drag in M^2 units is a pretty big ask. I am actually impressed with how well most companies' marketing depts are getting at reporting this data responsibly, even if it is in force (grams).

And in response to your comment about A2, as long as A2 is owned by Aerodyne, and is located in the greater Charlotte area the units will be in imperial. I know plenty of aerodynamicists that spend countless hours at Aerodyne that would be fine with metric units, but the people that they are producing data for would pretty much go sideways if information was presented to them in metric. And they more than occasionally attend tests, so the data has to be in imperial. As is usually the case, follow the money.
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Re: Giro Aerohead [Tom A.] [ In reply to ]
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especially when it appears Giro cannot even get the numbers they use to even agree on the same page on their website. (grams drag and watts not even close based on stnd conversions used) CdA would be so much more useful. Right now you can look at what they provided and guess which is what they intended and which is a typo
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Re: Giro Aerohead [pyrahna] [ In reply to ]
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I noticed while looking through the Grio website, if you're looking to justify the Ultimate vs the standard, the ultimate comes with the clamshell and an extra lens, a $110 value and the standard does not.

Also, the textreme looks cool, so that's gotta be worth something.
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Re: Giro Aerohead [pyrahna] [ In reply to ]
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pyrahna wrote:
Surface area or frontal area?


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The other major difference is the shell material: the Aerohead Ulimate MIPS uses TeXtreme carbon fiber while the Aerohead uses the traditional plastic. The use of TeXtreme allows Giro to reduce the frontal area by 2%.
(Cyclingnews)

I'd be curious to know the technical reason that TeXtreme allows the 2% reduction in frontal area. I'd assume it has something to do with passing a Snell test (or whatever the certifying test is) since I think the plastic cover has basically no significant stress on it except in crashes? And I'd thought that carbon fiber isn't that great at handling the kinds of impacts you'd expect in a crash.

The cynic in me suspects it could be just a way to justify a higher margin on a premium helmet.
Last edited by: trail: May 20, 16 9:35
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Re: Giro Aerohead [trail] [ In reply to ]
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I don't know, but I suspect that the textreme allows the impact force to spread over a larger area of foam....thereby needing less to pass the test.
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Re: Giro Aerohead [pyrahna] [ In reply to ]
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pyrahna wrote:
I agree there needs to be a standard reporting metric. And I agree with the way you want to do it. On the other hand asking marketing people and the average athlete to comprehend drag in M^2 units is a pretty big ask. I am actually impressed with how well most companies' marketing depts are getting at reporting this data responsibly, even if it is in force (grams).

And in response to your comment about A2, as long as A2 is owned by Aerodyne, and is located in the greater Charlotte area the units will be in imperial. I know plenty of aerodynamicists that spend countless hours at Aerodyne that would be fine with metric units, but the people that they are producing data for would pretty much go sideways if information was presented to them in metric. And they more than occasionally attend tests, so the data has to be in imperial. As is usually the case, follow the money.

That's why I said that it's still ok to "translate" into typical watts, typical time savings, etc. but at least provide the CdA values since those "typical" values require specific assumptions (that tend not to be specified).

The units thing is funny and really isn't a big deal IF the people using the non-standard units actually list them. I looked at a recent A2 output and the fact that they didn't label the units on the CdA column was causing some confusion. In any case, what's the big deal about using m^2 anyway? They already list the balance reading in grams and calculate the power estimates in watts :-/ Besides, the units on the CdA value don't just represent area, but actually "drag area" which most people really don't have an intuitive feel for anyway, so it's really just a scaling number. Not reporting in m^2 for their cycling equipment tests is just being lazy. It's not the raw output, but a standardized calculated value. Just change the danged cycling test spreadsheet, no?

http://bikeblather.blogspot.com/
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Re: Giro Aerohead [Tony5] [ In reply to ]
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Tony5 wrote:
TriTamp wrote:
Regarding the shield. How difficult would it be to take shield off and attach on top of helmet while riding? I'm thinking if it starts to rain and I need to remove the shield.


It is not easy, but not impossible. The six magnets are quite strong. I would say it would be more difficult to remove the visor from the top of the helmet to use it again than to initially take it off.

Tony V

That is probably what I am most interested in for this helmet and the drag data with the shield on top. That or the capability of the shield to shed water. For some reason, most of my events have either some rain or heavy mist and I have to lift the visor of my current helmet in order to see. After things dry out a bit it is very easy to put back down.
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Re: Giro Aerohead [LOW2000] [ In reply to ]
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LOW2000 wrote:
Also, the textreme looks cool, so that's gotta be worth something.

The textreme look makes it worth the $550.
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Re: Giro Aerohead [jeffp] [ In reply to ]
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jeffp wrote:
especially when it appears Giro cannot even get the numbers they use to even agree on the same page on their website. (grams drag and watts not even close based on stnd conversions used) CdA would be so much more useful. Right now you can look at what they provided and guess which is what they intended and which is a typo

Yeah I hadn't seen that page. It's clearly messed up. Jim said the aerogeeks article quoted the ERO numbers and here's what that article said:

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"At the track, Giro found the Aerohead saved 15 watts when compared to the Advantage (nine watts versus the Air Attack Shield), and the Ultimate saved an additional two watts."
I'm betting this is in fact what Jim measured. Jim's testing would have been on the track so probably 25-30mph range, though I'm not 100% sure what speed the watts difference is calculated at. Whether we believe it's truly this large a difference on average across different riders is another question. Also noone ever seems to want to report standard errors, but I suppose we have to get them to report units first (preferably CdA) and work on s.e.'s later!
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Re: Giro Aerohead [TriTamp] [ In reply to ]
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TriTamp wrote:
Regarding the shield. How difficult would it be to take shield off and attach on top of helmet while riding? I'm thinking if it starts to rain and I need to remove the shield.

They showed this helmet on this week's GCN show...specifically removing the visor and snapping it higher up and upside down.
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Re: Giro Aerohead [trail] [ In reply to ]
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I also found it odd that the CF-shell helmet would weigh the same. Density of the CF is ~1.8 vs PC at ~1.2. You should be able to produce a thinner shell and get equivalent or greater stiffness from the composite shell. They also chose to play with the geometry. So a bit tough to say for sure - just unlikely that it all shakes out at the same weight.
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Re: Giro Aerohead [SBRinSD] [ In reply to ]
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SBRinSD wrote:
I also found it odd that the CF-shell helmet would weigh the same. Density of the CF is ~1.8 vs PC at ~1.2. You should be able to produce a thinner shell and get equivalent or greater stiffness from the composite shell. They also chose to play with the geometry. So a bit tough to say for sure - just unlikely that it all shakes out at the same weight.

The other thing to consider, is that the Ultimate is solid while the base Aerohead is vented, so that may account for that difference as well. I have only been able to test the Aerohead.
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Re: Giro Aerohead [lanierb] [ In reply to ]
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except folks testing at track had before commented on how bad the attack was(not by name but by inference) and that the a2 was to go to helmet when you don't test based on their testing there. this however says the salad bowl is better
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Re: Giro Aerohead [jeffp] [ In reply to ]
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jeffp wrote:
except folks testing at track had before commented on how bad the attack was(not by name but by inference) and that the a2 was to go to helmet when you don't test based on their testing there. this however says the salad bowl is better
One of the problems of all this folk lore is it's hard to collect and verify. I've talked to Jim extensively and tested the Advantage on the track versus maybe 6-8 other helmets, and I never heard Jim say that, and certainly didn't find that myself, but that doesn't mean it isn't what other people found. My experience has been that the newer helmets have generally been better than the Advantage, but that many of them are about the same as each other (for me). I thought that Jim was a fan of the Specialized, but I might not be remembering right.
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Re: Giro Aerohead [lanierb] [ In reply to ]
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I never heard anything positive about the attack other than to not get it.

a2 works best for me, thus far vs quite a few other lids I have tried, but I really rotate it back
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Re: Giro Aerohead [Tom A.] [ In reply to ]
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When we started testing a lot there we insisted on m^2. All of A2's spreadsheets for bike testing has that column now.



Heath Dotson
HD Coaching:Website |Twitter: 140 Characters or Less|Facebook:Follow us on Facebook
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Re: Giro Aerohead [jeffp] [ In reply to ]
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I've never seen the salad bowl test better. I've seen a few tested too. Again it is rider dependant.

The A2 has been, probably 95% of the time, in the top three of all tested helmets. It is rarely the fastest helmet. The Selector is pretty good overall as well.

My intel on the new AeroHead has been the same. It has been the best for everyone that has tested. Hopefully I'll personally get back into A2 Wind Tunnel and give it a whirl soon. All my time there lately has been from the outside looking in.


jeffp wrote:
except folks testing at track had before commented on how bad the attack was(not by name but by inference) and that the a2 was to go to helmet when you don't test based on their testing there. this however says the salad bowl is better



Heath Dotson
HD Coaching:Website |Twitter: 140 Characters or Less|Facebook:Follow us on Facebook
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Re: Giro Aerohead [chrisgrigsby] [ In reply to ]
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Anyone?


chrisgrigsby wrote:
Anyone care to break down the fine print for me on the Giro time/drag savings chart here: http://www.giro.com/...tm_campaign=homepage

I wouldn't come anywhere near putting out 400 watts over 40k, so how do I scale this to my own FTP? Could I use the wind average drag data deltas to equate it to my typical average power output and speed?

Also, is the baseline the original Advantage or the Advantage 2 helmet?

Best,
Chris
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Re: Giro Aerohead [Jim@EROsports] [ In reply to ]
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Any regular people used or tested one of these yet?
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Re: Giro Aerohead [AforEffort] [ In reply to ]
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I've got one of these ordered from Trisports coming backordered for August
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Re: Giro Aerohead [iron snorks] [ In reply to ]
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Which one did you order?

blog
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Re: Giro Aerohead [Jim@EROsports] [ In reply to ]
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Looking forward to this one... may have to buy a new aero lid in early 2017.
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Re: Giro Aerohead [iron snorks] [ In reply to ]
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I have seen two stores now that list 6/30 as the expected delivery date. However most other locations say "expected August delivery". I am thinking about trying the 6/30 stores and hope for the best. I just wanted to use my tri sports discount
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