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Improving your Aerodynamics -Good Website
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Jorgan




Joined: 12 Nov 2007
Posts: 16097
Location: alles was ich bin, alles was ich war

PostPosted: Mon Mar 13, 2017 9:49 am    Post subject: Improving your Aerodynamics -Good Website Reply with quote

I happened upon this spreadsheet; a good guide to the best/most cost effective ways to improve your CdA.

http://aeroweenie.com/aero-assistant.html

If you're racing me this year, move along......
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SidSnot




Joined: 02 Sep 2005
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PostPosted: Mon Mar 13, 2017 10:00 am    Post subject: Reply with quote

I like the fact that if Disc Brakes is selected "for shame" is the comment
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Doca




Joined: 27 Feb 2014
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PostPosted: Mon Mar 13, 2017 10:19 am    Post subject: Reply with quote

Looks like I need some new tires Sad
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Gus




Joined: 07 Sep 2007
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Location: Freezing my nads off in Aberdoom

PostPosted: Mon Mar 13, 2017 10:25 am    Post subject: Reply with quote

If this site could speak:

"In a head-wind, you will go backwards. In a tail-wind you will win every race."
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PhilleusPhogg




Joined: 11 May 2015
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PostPosted: Mon Mar 13, 2017 11:16 am    Post subject: Reply with quote

Cheers for the link, humerous and useful!

I'm shocked that upgrading to a disc from say 808s would only buy 4s, whereas different skewers could be an 11s saving. I didn't even know that was a thing Smile

Nicely reiterates: position, position, position .... then get a skin suit
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Jorgan




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

PostPosted: Mon Mar 13, 2017 11:55 am    Post subject: Reply with quote

Yes, forget bothering to upgrade your P2/3 to P5 for example.

My main areas were: position (surprise), fully integrated aerobar or high-end (fragile) tyres. That said, for the purposes of longer distance events, I think I might struggle to get a much better position, without the Tunnel and even then it could compromise comfort/power.

At the moment I'm going after the very small stuff, that all adds up.
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Jorgan




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

PostPosted: Mon Mar 13, 2017 11:55 am    Post subject: Reply with quote

Yes, forget bothering to upgrade your P2/3 to P5 for example.

My main areas were: position (surprise), fully integrated aerobar or high-end (fragile) tyres. That said, for the purposes of longer distance events, I think I might struggle to get a much better position, without the Tunnel and even then it could compromise comfort/power.

At the moment I'm going after the very small stuff, that all adds up.
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explorerJC




Joined: 20 Oct 2005
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PostPosted: Mon Mar 13, 2017 12:37 pm    Post subject: Reply with quote

yep, drop 8k on a new bike to save 4 seconds...
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Jorgan




Joined: 12 Nov 2007
Posts: 16097
Location: alles was ich bin, alles was ich war

PostPosted: Mon Mar 13, 2017 2:38 pm    Post subject: Reply with quote

I'd love to stick Tri Rig Alpha X bars on my bike, but I don't have $1k plus import charges to spare!
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Andy916




Joined: 08 Oct 2011
Posts: 644
Location: Cambridge

PostPosted: Tue Mar 14, 2017 11:33 am    Post subject: Reply with quote

PhilleusPhogg wrote:
<snip> I'm shocked that upgrading to a disc from say 808s would only buy 4s


I'm sceptical about that particular prediction so browsed the blog to get some background on the author. Useful, down-to-earth stuff, and happily some of it aimed at a very similar spec of P2C to mine ("venerable, still competitive").

My own testing gave me a 30-60s saving using a cover as opposed to without, on a 66mm Reynolds Strike on a P2C, on a 20 mile / 60 min undulating test route. That was based on 6 replicate runs of each, at almost-identical heart-rate and perceived effort (power measurements unavailable for that particular test as I use Powertap and a Wattbike). The consistency and magnitude of the difference surprised me, and I used the cover for IMW on the basis of that (gut feeling comparing to surrounding riders was that the cover was approx neutral on the hillier Pembrokeshire course). Have since bought a Flo alloy/carbon disk and will repeat the test including that at some point.
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SGreg




Joined: 30 Jun 2010
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PostPosted: Tue Mar 14, 2017 11:51 am    Post subject: Reply with quote

Hmmm I was certainly not considering the Disc cover at Wales!

And your Gut feeling of Neutrality would lead me to stay with that decision.

As I assume the disc was providing a perceived advantage on the flats/downs, but a perceived hindrance on the climbs.

As far as I am concerned I do not need any more hindrance on the endless climbs in a wales and any perceived hindrance will only lead to further frustration. I am sure that mental boost would offset the possible gains made in the downs/flat.

I have always found the Extra rotational weight to be the biggest noticeable factor of the disc cover. I don't find the Aero benefits to be perceivable. I'm sure they are when timed and analysed but I can't tell 99% of the time its an improvement. But on climbing I feel I can notice it!

And that in itself is enough to leave it at home for wales.
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Andy916




Joined: 08 Oct 2011
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PostPosted: Tue Mar 14, 2017 3:21 pm    Post subject: Reply with quote

SGreg wrote:
As I assume the disc was providing a perceived advantage on the flats/downs, but a perceived hindrance on the climbs.

...

I have always found the Extra rotational weight to be the biggest noticeable factor of the disc cover. I don't find the Aero benefits to be perceivable. I'm sure they are when timed and analysed but I can't tell 99% of the time its an improvement. But on climbing I feel I can notice it!


Yup, I was within sight of a few riders for 1-2hrs at a time and I would fall back slightly on the climbs and catch up elsewhere. Could be that we managed the variability differently of course, but at 60kg I normally climb well. My bike split was 6:23, compared to 6:05 IMUK, 6:15 at Lanza and 5:58 at Forestman (the last 3 on the same setup minus the wheel cover)

Yes, you feel the extra weight immediately but careful timing tells another story.
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Jorgan




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

PostPosted: Wed Mar 15, 2017 9:52 am    Post subject: Reply with quote

I have an old-school Zipp 900 (pre dimple) and it weighs relatively little (950g). Add a Dura Ace ti cassette to that, and the whole thing with a tub is surprisingly light, and I would use it on any hilly course. Wind is the only reason not to use a disc in my opinion, and it would have to be a very strong crosswind.

You can feel the 'sail effect' of a disc, especially on motor circuits or airfield courses. Also, when I freewheel downhill in a tuck, I always catch people. That might be the rest of my set-up as well as the disc, but it certainly helps.

A disc is nearly always the fastest wheel.
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explorerJC




Joined: 20 Oct 2005
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PostPosted: Wed Mar 15, 2017 10:06 am    Post subject: Reply with quote

Jorgan wrote:
I have an old-school Zipp 900 (pre dimple) and it weighs relatively little (950g). Add a Dura Ace ti cassette to that, and the whole thing with a tub is surprisingly light, and I would use it on any hilly course. Wind is the only reason not to use a disc in my opinion, and it would have to be a very strong crosswind.

You can feel the 'sail effect' of a disc, especially on motor circuits or airfield courses. Also, when I freewheel downhill in a tuck, I always catch people. That might be the rest of my set-up as well as the disc, but it certainly helps.

A disc is nearly always the fastest wheel.


a fond memory of a very highly talented duathlete sitting in transition because a late notice banned discs at a world champs....not only did he train with a disc, he commuted with one Smile
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SGreg




Joined: 30 Jun 2010
Posts: 831
Location: High Peak

PostPosted: Wed Mar 15, 2017 10:25 am    Post subject: Reply with quote

Jorgan wrote:
You can feel the 'sail effect' of a disc, especially on motor circuits or airfield courses.



I said 99% of the time I can't feel it. I have felt the Sail effect plenty of times but it probably accounts for 1% of my riding.

I'm not doubting the disc is faster on most course's and even possibly faster on Wales.

I'm still not going to use it. I won't be near the Kona spots so 2-3 mins is neither here nor there. 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.

I've had this on Sprint courses that were lumpier than expected. I don't need it in wales.

Remember Ironman is 90% mental!!!

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