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Jorgan




Joined: 12 Nov 2007
Posts: 15909
Location: alles was ich bin, alles was ich war

PostPosted: Wed Mar 15, 2017 10:34 am    Post subject: Reply with quote

SGreg wrote:
The sensation of dragging the F**$ing disc up endless hills will be there the entire race and lead me to bad moods and a less enjoyable bike.


A disc, or a wheel with a cover? A good quality tubular disc can weigh less than a carbon deep rim:

My '2003 pattern' Zipp 900 tubular: 950g
2017MY 900 disc (tub): 935g
808 FC Tubular Rear: 930g
808 FC Clincher Rear: 1030g

If you put a Ti cassette like the Shimano DA on a disc, and a standard cassette on a deep clincher rim, the difference will be even more. So you can ride a lighter, faster wheel, that makes you sound like a Boss.... or a deep clincher.

It is all in your head. Case closed Wink
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jibberjim




Joined: 15 Aug 2008
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PostPosted: Wed Mar 15, 2017 11:18 am    Post subject: Reply with quote

Jorgan wrote:
A disc is nearly always the fastest wheel.


I'm pretty sure that the site is just doing 0 yaw, where disc is almost irrelevant, but of course, 0 yaw is unknown.
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SGreg




Joined: 30 Jun 2010
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PostPosted: Wed Mar 15, 2017 11:25 am    Post subject: Reply with quote

No sorry Me and andy916 were discussing covers.

They will always be heavier.
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Jorgan




Joined: 12 Nov 2007
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PostPosted: Wed Mar 15, 2017 11:31 am    Post subject: Reply with quote

jibberjim wrote:
Jorgan wrote:
A disc is nearly always the fastest wheel.


I'm pretty sure that the site is just doing 0 yaw, where disc is almost irrelevant, but of course, 0 yaw is unknown.


You mean people don't race in wind tunnels? Idea

There have been a few studies on the most common yaw angle experienced, and of course it depends on weather and speed ridden, but 95% of your time under 10 degrees seems popular, but that doesn't mean it's 0 yaw!
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Andy916




Joined: 08 Oct 2011
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PostPosted: Wed Mar 15, 2017 12:28 pm    Post subject: Reply with quote

SGreg wrote:
I also fear Aerodynamics may not be the limiting factor in my descending speed, Overuse of the brakes will be Crying or Very sad


Practice the course once or twice beforehand if you can. Look and think further ahead. The course is moderately tricky; I fitted decent brakes to my P2C (Magura hydraulics) before taking it to Wales, as IMUK and Lanza were sketchy at times on the standard calipers (Reynolds blue pads to match the carbon rims).
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Cat5 in the Hat




Joined: 14 Mar 2011
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Location: Berks

PostPosted: Wed Mar 15, 2017 12:58 pm    Post subject: Reply with quote

Jorgan wrote:
jibberjim wrote:
Jorgan wrote:
A disc is nearly always the fastest wheel.


I'm pretty sure that the site is just doing 0 yaw, where disc is almost irrelevant, but of course, 0 yaw is unknown.


You mean people don't race in wind tunnels? Idea

There have been a few studies on the most common yaw angle experienced, and of course it depends on weather and speed ridden, but 95% of your time under 10 degrees seems popular, but that doesn't mean it's 0 yaw!


There is a huge difference in yaw between TTers and Triathletes and this should be considered when reviewing data. Always check the quoted speed that the test was run at.

TTing is a typically higher speed sport, meaning the yaw angle (i.e. relative airflow angle) will tend towards 0degrees but be reasonably low.

Slower moving traffic such as IM Triathletes, and to some extent shorter distance triatletes, will experience a greater yaw angle.
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jibberjim




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PostPosted: Wed Mar 15, 2017 1:07 pm    Post subject: Reply with quote

Cat5 in the Hat wrote:
There is a huge difference in yaw between TTers and Triathletes and this should be considered when reviewing data. Always check the quoted speed that the test was run at.


Are you suggesting that triathletes are slow?
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Jorgan




Joined: 12 Nov 2007
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PostPosted: Wed Mar 15, 2017 1:48 pm    Post subject: Reply with quote

Cat5 in the Hat wrote:

Slower moving traffic such as IM Triathletes, and to some extent shorter distance triatletes, will experience a greater yaw angle.


But I'm thinking about it from my perspective, not someone who does a 15h Ironman. People who take 7h to do the bike probably aren't sweating the (equipment) details. If you're here discussing this, I'd like to think it's because it does matter in reality, rather than you just need to stop eating pies and train more.
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Chrace




Joined: 28 Apr 2010
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PostPosted: Wed Mar 15, 2017 1:53 pm    Post subject: Reply with quote

Jorgan wrote:
Cat5 in the Hat wrote:

Slower moving traffic such as IM Triathletes, and to some extent shorter distance triatletes, will experience a greater yaw angle.


But I'm thinking about it from my perspective, not someone who does a 15h Ironman. People who take 7h to do the bike probably aren't sweating the (equipment) details. If you're here discussing this, I'd like to think it's because it does matter in reality, rather than you just need to stop eating pies and train more.

Surplus income and midlife crisis makes pie-habit irrelevant and bling the king.
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Jorgan




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PostPosted: Wed Mar 15, 2017 2:24 pm    Post subject: Reply with quote

Chrace wrote:

Surplus income and midlife crisis makes pie-habit irrelevant and bling the king.


Best buy a disc then! In reality, I think a lot of people are 'afraid' of buying a piece of kit like a disc, because it makes a statement. Yet they hope no-one will notice them pedaling their P5 at 16 mph.
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Cat5 in the Hat




Joined: 14 Mar 2011
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PostPosted: Wed Mar 15, 2017 5:39 pm    Post subject: Reply with quote

Jorgan wrote:
Cat5 in the Hat wrote:

Slower moving traffic such as IM Triathletes, and to some extent shorter distance triatletes, will experience a greater yaw angle.


But I'm thinking about it from my perspective, not someone who does a 15h Ironman. People who take 7h to do the bike probably aren't sweating the (equipment) details. If you're here discussing this, I'd like to think it's because it does matter in reality, rather than you just need to stop eating pies and train more.


Are you spying on me? 6 months of minimal training has me looking like a pie-eater and I do need to train more Mad

For a given crosswind vector the yaw angle will reduce the faster you travel.

In-line with your original comment it was the Flo guys who found most (83%) of wind was 10degree yaw or less based on a 3 HIMs and Kona link.

There is a world apart from someone doing 42kph over a 25mi TT or a 112 mi IM course (4:20 ish bike) compared to someone doing a 6hr bike (30kph).

A lot of the tunnel and testing data is shown at a speed that is rarely attained by regular triathletes. Flo seem to be bucking this trend with their information, which is a Good Thing.

Anyhow, I think it matters. Disc is always the correct answer.
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Cat5 in the Hat




Joined: 14 Mar 2011
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PostPosted: Wed Mar 15, 2017 5:41 pm    Post subject: Reply with quote

jibberjim wrote:
Cat5 in the Hat wrote:
There is a huge difference in yaw between TTers and Triathletes and this should be considered when reviewing data. Always check the quoted speed that the test was run at.


Are you suggesting that triathletes are slow?


Not when it comes to opening their wallets for 'free speed'.
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JaRok2300




Joined: 01 May 2014
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PostPosted: Thu Mar 16, 2017 8:23 am    Post subject: Reply with quote

Is there not an argument that slower riders benefit just as much (if not more) than faster ones because, although the absolute saving from aero is less, they benefit from it over a longer period of time.
I definitely get the comment about making a statement, I only recently bought a disc cover and second hand aero helmet for exactly that reason. Not sure if it was because I got any faster or just thicker skinned.
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Jorgan




Joined: 12 Nov 2007
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PostPosted: Thu Mar 16, 2017 8:51 am    Post subject: Reply with quote

It's also worth remembering that aurally, not all discs are created equal. A cover or a 'skinned' disc wheel like a Flo or HED does not make the Airwolf sound of a structural disc. I seem to remember the HED Jet sounding a bit like a biscuit tin, rather than the desired 'Air Cav' scene in Apocalypse Now.
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Chrace




Joined: 28 Apr 2010
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PostPosted: Thu Mar 16, 2017 9:30 am    Post subject: Reply with quote

Cat5 in the Hat wrote:
A lot of the tunnel and testing data is shown at a speed that is rarely attained by regular triathletes. Flo seem to be bucking this trend with their information, which is a Good Thing.

Indeed. When I see "Saves you 156w at 30mph!" I kind of have to ignore it. Going downhill at 30mph I start considering whether it's worth to keep pedaling, and certainly not at any significant power. Smile
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