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PostPosted: Thu Jun 28, 2012 4:08 am 
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Sorry spytech if I misread into your previous comment. My fault.


For your answer, the typical number is that 80% of a rider's power is used to overcome the effects of aero drag. 2/3rds of that is caused by the rider and 1/3rd by the bike. Weight and rolling resistance have smaller effects. So obviously a more aero/better fit bike will make a bigger difference than a frame upon which you sit more upright and ride like a "parachute" in the wind.

Image

So if you are optimally positioned on a frame and have good flexibility to ride a large drop, you have theoretically maxed out the drag caused by the rider (can add more aero helmet, clothing, shoe covers....etc.). However there is still that 1/3rd hanging out there for the drag of the frame. If you are looking to save every watt, your position is already maximized, have aero wheels, then the frame leaves one of the last places to save some time. At least that is how I see it.


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PostPosted: Thu Jun 28, 2012 3:11 pm 
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Trek's white papers are the benchmark of the industry. Still no error bars and some information lacking about their testing protocols but the presentation is really good

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PostPosted: Thu Jun 28, 2012 5:29 pm 
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spytech wrote:
i wasnt trying to argue, i was trying to know what the difference is. and how much of a difference does an aero frame make compared to the overall effect your body and frame have.


A frame's around 15% of total drag and around 3% of total mass. So I think if you buy this "relative magnitude" argument you're on the wrong forum. Nobody denies we're obsessing with marginal differences here.

I was more interested in handlebar-rider interactions than frame-rider interactions. They include handlebar differences in their test, which they claim is 90 grams (sic) drag reduction. So if I assume bars interact with rider (I think it's no-brainer they do) and matter much less than this, try adding 90 grams to the Trek Madone 7.9 curve here and see if that affects things:

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added: I now see they use "spec'ed" wheels in the test, as well. So this plot is virtually useless.

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PostPosted: Thu Jun 28, 2012 5:54 pm 
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Could someone who has the white paper please post a pdf copy of it or post a link to some place we can read it? Thanks.

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PostPosted: Thu Jun 28, 2012 6:08 pm 
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Will there be a problem riding wider wheels like the new FC Zipps in the frame?

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PostPosted: Thu Jun 28, 2012 6:10 pm 
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djconnel wrote:
A frame's around 15% of total drag and around 3% of total mass. So I think if you buy this "relative magnitude" argument you're on the wrong forum. Nobody denies we're obsessing with marginal differences here.

I was more interested in handlebar-rider interactions than frame-rider interactions. They include handlebar differences in their test, which they claim is 90 grams (sic) drag reduction. So if I assume bars interact with rider (I think it's no-brainer they do) and matter much less than this, try adding 90 grams to the Trek Madone 7.9 curve here and see if that affects things



Doubtful. This is the forum where people buy certain bike parts to save them a few grams of weight. And spend good coin in that process too. If anything, this is a perfect place as people are looking to save minute amounts of weight to make their bike lighter and "faster". However ignore the benefits of being more aero. I also would not call those marginal differences myself, but we probably have different definitions of "marginal." If I could save watts and get "free speed" I would be all over that. Especially if racing put the food on the table for me (which it doesn't).


The typical number as I stated above is 80% of a rider's power is used to overcome aero drag. 2/3rds of that is rider and 1/3rd is bike. That means the bike makes up around 26.67% of the total drag, rider makes up 53.33%, and 20% is other. I would not consider the frame drag to be marginal as there is time to gain there. 90g of additional drag is a lot. At 40 km/h you save 50s over a 40K for 100g of drag reduction. I will take the benefit of being more aero. Being aero also works riding in the peleton, not just being on a solo breakaway.


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PostPosted: Thu Jun 28, 2012 6:44 pm 
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djconnel wrote:
added: I now see they use "spec'ed" wheels in the test, as well. So this plot is virtually useless.


Not as a marketing tool it isn't :wink:


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PostPosted: Thu Jun 28, 2012 6:47 pm 
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tranzformer wrote:
Could someone who has the white paper please post a pdf copy of it or post a link to some place we can read it? Thanks.


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PostPosted: Thu Jun 28, 2012 7:11 pm 
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@ 53x12: Thanks for the explanation. That makes sense.

@ DJ: Thanks. I missed that post with the white paper.

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PostPosted: Thu Jun 28, 2012 8:52 pm 
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djconnel wrote:
A frame's around 15% of total drag and around 3% of total mass. ... Nobody denies we're obsessing with marginal differences here.

Why spoil thing? That's like saying (spoiler warning) that there is no Santa.


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PostPosted: Thu Jun 28, 2012 9:16 pm 
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Seems Velonews got their hands on the new bikes, and it looks pretty hot in the pictures. The front end is certainly better looking than it was when it showed up as a prototype a few weeks ago. The clean front brake, and the absence of the rear brake really make it look nice. I guess I didn't understand the Trek pages, the rear brake is a single bolt brake? It looks just like the painfully unreliable brakes that I've had on Tri bikes. Something about the extra long internal cable, tight clearances, and difficulty to adjust on the fly, always seem to make these a bit finicky.

I really, really like the bike, but I think the rear brake thing is a deal breaker for me.

http://velonews.competitor.com/2012/06/ ... one_225938


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PostPosted: Thu Jun 28, 2012 9:19 pm 
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^ I don't see why Trek wouldn't think through those things. Especially with their dealer network.

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PostPosted: Thu Jun 28, 2012 9:47 pm 
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i really like the bike, but i just looked at the u5 vapor sub 5g paint - its $1049 option. WOW. how much will the frameset cost for 7 series? how much was the 6.9ssl frameset?


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PostPosted: Thu Jun 28, 2012 9:55 pm 
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"I now see they use "spec'ed" wheels in the test, as well. So this plot is virtually useless." - DJ

I agreee with DJ here. That plot is virtually worthless as far as judging aerodynamics. I can see using different handlebars, but to use different wheels is like shooting Cervelo(Fulcrum Racing Ts?) in the foot, at least the Venge had 45mm deep wheels.


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PostPosted: Thu Jun 28, 2012 10:10 pm 
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Yeah, front brake looks 100x better then it did from the initial RSNT shots.

tranzformer wrote:
Will there be a problem riding wider wheels like the new FC Zipps in the frame?


Looks like a lot of chain stay clearance.

http://velonews.competitor.com/files/20 ... IK5447.jpg

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Posted: Thu Jun 28, 2012 10:10 pm 


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