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Slowtwitch Forums: Triathlon Forum:
2010 Trek TTX - Yes or No???

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pyrahna

Jul 6, 09 8:52

Post #51 of 77 (1111 views)

Re: 2010 Trek TTX - Yes or No??? [Carl] [In reply to]	Can't Post

Out of curiosity what did you test it against? If you tested it against a p3 and a transition then you could do a percentage difference between your test and theirs. It's not ideal but gets you int he ball park.
Also what was the justification for the vertical dropouts and not having the seatstay/seattube junction being inline w/ the airflow? Really nice work overall though and it's interesting to see someone bring something different to the table (i.e. the kamm tail and the completley hidden cables.

Carl

Jul 6, 09 8:52

Post #52 of 77 (1111 views)

Re: 2010 Trek TTX - Yes or No??? [dcsxtri10] [In reply to]	Can't Post

For now I have nothing more to offer than what Dean (Gore) already is quoted as saying in the article. I think we're in the same boat as a lot of folks when it comes to the real answer to that question, though.

Carl
Trek Speed Design

Tom A.

Jul 6, 09 8:53

Post #53 of 77 (1107 views)

Re: 2010 Trek TTX - Yes or No??? [Carl] [In reply to]	Can't Post

In Reply To:

Unfortunately a static shot from what is actually a composite high-speed video (i.e. each shape shot separately and then lined up side by side for the comparison) doesn't let you appreciate the full effect. What you'd see is that the flow detaches at the on the leeward side of each shape at the same place.

Thanks Carl...but are you saying that it actually IS "identical" drag to an 8:1 section...or is it actually just better than an equivalent width 3:1 section? (Which is still a good thing, of course ;-)

desert dude

Jul 6, 09 9:11

Post #54 of 77 (1074 views)

Re: 2010 Trek TTX - Yes or No??? [Rappstar] [In reply to]	Can't Post

Both bikes fit nicely, by virtue of their design, into the "fit is critical" message that Trek and Specialized are putting forth.

Quote:

Then it's going to be close to vaporware as the majority of Specialized and Trek dealers that I've been in do not stock the TT bikes. Nor, even though many of them have been to a fit school of some sort, can most of them fit a bike properly to save their life.

Brian Stover Accelerate3 Coaching, Blog
Save at TriSports.com - use code BSTOV-S

rmur

Jul 6, 09 9:23

Post #55 of 77 (1058 views)

Re: 2010 Trek TTX - Yes or No??? [Carl] [In reply to]	Can't Post

In Reply To:

All in good time...we just got back from the tunnel last week. Won't be able to compare to Specialized's data anyway...we didn't have a Shiv, used a different tunnel, different setup on the bike, etc etc.

Carl

okay fair enough on the different setup and tunnel ....

How about absolute or % reduction in drag compared to your older TTX (vs. yaw)? You must have had a control bike/setup with you?
_________________________________
Gizmo marketing specialist :-)

Paulo Sousa

Jul 6, 09 9:29

Post #56 of 77 (1050 views)

Re: 2010 Trek TTX - Yes or No??? [Carl] [In reply to]	Can't Post

It would appear that Trek is revolutionizing low-speed airfoil design...
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pstriathlon.com

Carl

Jul 6, 09 9:30

Post #57 of 77 (1046 views)

Re: 2010 Trek TTX - Yes or No??? [pyrahna] [In reply to]	Can't Post

You would think that percentage difference (or offset) calculation would be straightforward, but things like that tare subtraction they did complicate matters because the contribution of the fixture drag to the overall drag varies as you sweep thru yaw. Our stance on vertical dropouts hasn't changed since the first TTX. And finally, as far as the wind is concerned, that junction at the seattube-seatstay is inline with the airflow. Not an easy visualization, I'll grant you.

Carl
Trek Speed Design

Paulo Sousa

Jul 6, 09 9:38

Post #58 of 77 (1031 views)

Re: 2010 Trek TTX - Yes or No??? [renegade027] [In reply to]	Can't Post

In Reply To:

Paulo, would you care to explain a bit more, please [..]

No, not really ;-)

Here's some reading if you're interested: http://www.prod.sandia.gov/...l.pl/2008/081781.pdf
-

pstriathlon.com

Carl

Jul 6, 09 9:51

Post #59 of 77 (1003 views)

Re: 2010 Trek TTX - Yes or No??? [Tom A.] [In reply to]	Can't Post

Yes ;-)

In the end it's all about pushing that stall point out as far as you can to give the bike the broadest possible band of low drag. What's nifty is how the Kamm virtual tail delays the stall point (in part) by bending as yaw increases. Hard to capture with the high-speed and smoke, but easy to see in CFD...for those with the means and the motive to check it out on their own.

Carl
Trek Speed Design

pyrahna

Jul 6, 09 9:52

Post #60 of 77 (1000 views)

Re: 2010 Trek TTX - Yes or No??? [Paulo Sousa] [In reply to]	Can't Post

It seems as though this paper says that a cut off tail is not as good as a full tail. I think that is obvious despite what cyclingnews quoted trek as saying. The question that is much more pertinent is whether a cut off tail of a much higher aspect ratio foil can be better than a smaller aspect ratio foil imposed by a goofey sanctioning body.

edit- Carl is actually saying for high degrees of yaw the kamm is as good as a high aspect ratio foil. This is where it gets really fuzzy (with my very limited experience) because cars certainly don't live in the high yaw areas that bikes do.

(This post was edited by pyrahna on Jul 6, 09 9:55)

Paulo Sousa

Jul 6, 09 9:55

Post #61 of 77 (993 views)

Re: 2010 Trek TTX - Yes or No??? [Carl] [In reply to]	Can't Post

In Reply To:

So what was the Re number for the CFD simulations?
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pstriathlon.com

littlefoot

Jul 6, 09 10:09

Post #62 of 77 (961 views)

Re: 2010 Trek TTX - Yes or No??? [dcsxtri10] [In reply to]	Can't Post

that was funny-HIV! :)

Carl

Jul 6, 09 10:14

Post #63 of 77 (945 views)

Re: 2010 Trek TTX - Yes or No??? [rmur] [In reply to]	Can't Post

Sounds like a good thing to put into a second edition of our white paper, eh? I hate being cagey, but like I said we're just back from our latest tunnel trip. Good stories can be told poorly if they're rushed. Perhaps more so in the detail-driven world of Slowtwitch, wouldn't you say?

(and yes, we did have a control frame...same one from our first white paper, in fact)

Carl - who really needs to get back to work
Trek Speed Design

Paulo Sousa

Jul 6, 09 10:32

Post #64 of 77 (927 views)

Re: 2010 Trek TTX - Yes or No??? [Carl] [In reply to]	Can't Post

In Reply To:

Carl - who really needs to get back to work

Can you reply to my question before you go back to work? Thanks.
-

pstriathlon.com

Carl

Jul 6, 09 10:58

Post #65 of 77 (884 views)

Re: 2010 Trek TTX - Yes or No??? [Paulo Sousa] [In reply to]	Can't Post

No, but I'll reply between mouthfuls.

We'll add that request to our list of "what do we put in the paper?" items.

Carl
Trek Speed Design

rmur

Jul 6, 09 11:31

Post #66 of 77 (845 views)

Re: 2010 Trek TTX - Yes or No??? [Carl] [In reply to]	Can't Post

In Reply To:

Just the facts will be fine sir ;-)
_________________________________
Gizmo marketing specialist :-)

istanford

Jul 6, 09 17:19

Post #67 of 77 (770 views)

Re: 2010 Trek TTX - Yes or No??? [usctriguy] [In reply to]	Can't Post

The Trek. No one, I mean no one, puts more time and money into their TT frames than Trek. There were not a lot of changes to the TTX because it works. Buried cables, Bayonet headset, and shortened seat stays added with stiffer and lighter carbon than the RED carbon.
All these bikes are coming up to par to each other. The Specialized, The Scott, the Giant, the P4, and Trek. I am looking at what is the simplest. Trek has been working on this bike for some time now and working with the guys who know the tech of this stuff. In the end though, if you can afford any of them you will not go wrong. Just remember, you have to live up to that bike. That is the hard part!

MITaerobike

Jul 7, 09 9:35

Post #68 of 77 (652 views)

Re: 2010 Trek TTX - Yes or No??? [Carl] [In reply to]	Can't Post

In Reply To:

Carl

We're game to do an independent wind tunnel test whenever you want. We've had excellent repeatability at A2 so I think that'd be a good choice.

Let me know or contact Mike Giraud at the tunnel directly and we can get the specifics figured out. Roughly 30 mph, +/-20 deg yaw at 5 deg increments, figure out specific stack and reach, components, etc.

You can contact me directly if you want via PM.

Thanks,

Mark Cote
Specialized Bicycle Components
Road Engineer/Aerodynamicist
--
Mark Cote
MITAerobike (ST, Twitter)
Specialized Bicycle Components
Road Engineer/Aerodynamicist

pyrahna

Jul 7, 09 9:55

Post #69 of 77 (606 views)

Re: 2010 Trek TTX - Yes or No??? [MITaerobike] [In reply to]	Can't Post

Can we get a P4 there too?

And I'll volunteer to be a 3rd party observer if you guys want it.

Tom A.

Jul 7, 09 10:09

Post #70 of 77 (587 views)

Re: 2010 Trek TTX - Yes or No??? [MITaerobike] [In reply to]	Can't Post

In Reply To:

Who are you guys going to appoint to run this "independent" test? :-)

MITaerobike

Jul 7, 09 10:51

Post #71 of 77 (528 views)

Re: 2010 Trek TTX - Yes or No??? [Tom A.] [In reply to]	Can't Post

Ideally one of the tunnels and their operators -- someone unbiased with a ton of tunnel experience. The rules would have to be mutually agreed upon between the companies.

Mark
--
Mark Cote
MITAerobike (ST, Twitter)
Specialized Bicycle Components
Road Engineer/Aerodynamicist

Rappstar

Jul 7, 09 10:54

Post #72 of 77 (520 views)

Re: 2010 Trek TTX - Yes or No??? [Tom A.] [In reply to]	Can't Post

In Reply To:

Who are you guys going to appoint to run this "independent" test? :-)

Assuming there is actual interest, I'm in favor of having a Slowtwitch contest. A2 is close to Herbert, so he can go and cover it. And we can have an essay-based (i.e., not just random) raffle for a slowtwitch referee from among the readers. I'm thinking something like you'd be responsible for airfare to around A2, and then (assuming a male), you and Herbert could stay together. H, I hope you don't mind me pimping you out here... Thoughts?

Andrew Coggan

Jul 7, 09 10:57

Post #73 of 77 (506 views)

Re: 2010 Trek TTX - Yes or No??? [Tom A.] [In reply to]	Can't Post

In Reply To:

Who are you guys going to appoint to run this "independent" test? :-)

I nominate Jim Martin.

p.VDB

Jul 7, 09 12:19

Post #74 of 77 (444 views)

Re: 2010 Trek TTX - Yes or No??? [pyrahna] [In reply to]	Can't Post

In Reply To:

Can we get a P4 there too?

And I'll volunteer to be a 3rd party observer if you guys want it.

I am already getting hungry!! Can't wait when you guys will publish the results.
_____________________
Paul | Medisch Forum

renegade027

Jul 7, 09 13:49

Post #75 of 77 (329 views)

Re: 2010 Trek TTX - Yes or No??? [Paulo Sousa] [In reply to]	Can't Post

Thanks for the reading :)

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