Hehe...I'll bet Cees would have something to say about that assumption... ;-)

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http://bikeblather.blogspot.com/

Somewhat along the same lines, I'm not convinced that air being dragged into the gap between the tire and the seat tube would increase the rotational drag enough to really matter in the first place.

The funny thing is...IIRC, the guy in the video repeated the same silly (IMO) claim...or did he just accidentally leave a word out too? ;-) I do remember that it's in the text accompanying the vid.

edit: I misremembered...the claim about the spinning wheels wasn't in the video...mea culpa. BUT, it IS in the accompanying text.

The video doesn't really add much, if anything, beyond what has been claimed in print IMHO.

BTW, I seem to recall actual drag curves on the P4 coming out after interbike. Now, granted, these weren't necessarily intended to be released by Cervelo (or were they??), but they're still "out there"...

Also, I take umbrage at your implication of holding manufacturers to differing standards...I'm an equal opportunity skeptic :-)

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http://bikeblather.blogspot.com/

I did? Where? I said I was going to inquire with LOOK. And it wasn't a mistranslated piece of a marketing material, it was from James Huang's piece on the bike (bikeradar.com & cyclingnews.com) - "Unfortunately we have no easy way of verifying that claim (Look says its wind tunnel facility at the Magny Cours race track in France is perhaps the only place that can run a test with spinning wheels) but the idea is intriguing and might carry some merit. In fact, LeMans cars are fitted with fender louvres specifically to relieve the high pressure buildup that Look calls to attention here. Whether or not this matters at the slower speeds typically encountered in a time trial is another matter entirely but it’s an intriguing idea nonetheless." [http://www.bikeradar.com/...amp;SOURCE=BRGENNEWS]

I have the catalog in front of me, which says what Chas says it does. But nevertheless there is a press piece out there that says otherwise. I simply said I was going to contact LOOK to find out what was going on.

For the record, I really like this bike, appreciate the work LOOK has done on it, and have been spending a fair bit of time going back and forth with LOOK so that I can really understand the geometry of the bike in order to write up and article.

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"Non est ad astra mollis e terris via." - Seneca | rappstar.com | FB - Rappstar Racing | IG - @jordanrapp

Yes...it's a place to store your Benito's Pizza slices...

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http://bikeblather.blogspot.com/

Dang! Why didn't this come up before I did those fairing tests using my wife's P3C? :-)

Did you cut up a pizza box for your "fairing"? If not...perhaps that's why you didn't see much difference? :-)

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http://bikeblather.blogspot.com/

My apologies...Tom A actually made the "credibility" statement and you quoted his response when making your own. When I mess up, I admit it. So, my bad.

Bob

So then, to be accurate, I never...and I quote you... "dismissed in hand their statements about the wheel gap simply because a word was missing from a translated piece of marketing material" either.

I just said that if that was TRULY what they were claiming (i.e. not a typo, or mispoken marketing gibberish), then that would put a "big dent in their credibility."

So...explain to me how what I originally said was "juvenile"? I think you were reading more into it than what was actually there... :-P

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http://bikeblather.blogspot.com/

Although the pizza box would work too. Never heard of Benitos pizza before though.

Tom A, reading what you've added here I am inferring that you don't buy into Look's contention of the distance between the frame and the wheel as an aerodynamic benefit. It that a good read?

What do you think of what Look is claiming about the distance from the wheel to the frame and the airflow through it? Any validity to this?

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Tom Demerly
The Tri Shop.com

No. I'm fairly convinced that for the design iterations they analyzed and tested that they ultimately went with the one that worked the best on that frame given the constraints of how they configured other features on it (i.e. the seatstay junction). In other words, it's most likely a benefit for their design and their constraints.

However, a lot of the presentation of this feature on the 596 (i.e. the large gap) has inferred that they discovered that for some reason everyone else is doing it wrong. Don't get me wrong...they don't come out and explicitly say that, it's just the general tenor of how it's been rolled out.

Granted, I can understand how a lot of the attention being paid to this is because they knew they would have to answer to why they used a big gap. So...they addressed it from the start. That's fine...and honestly, I give them credit for actually analyzing and testing it and going with what they thought is best for that bike. But, if the real reason they did it this way is because they had other design constraints they were working against (even if it was something like their ProTour sponsored teams didn't want horizontal dropouts or something), they shouldn't try to imply that how they did it is better than what is done in other designs that don't have those same constraints.



Honestly, I really don't know what to think, since besides some generic flow diagrams there really isn't much to judge by.

But, one thing the whole concept (as it's been presented) hinges on is that the wheel/tire interacting with the viscosity of the air "pulls" enough air into that gap to be a hindrance. I'm not convinced that is the case. After all, a simple thing you could do to "calibrate" yourself to the magnitude (if any) of the speculated effect is to just grab your P3C and put it in a bike stand and then time how long it takes to coast down your rear disc between 2 given speeds. Do this with a wide gap and then with a small gap and see if there's a difference. Now, I haven't done this myself (I don't have a bike with a significant wheel cutout...just my lowly P2K) but my guess would be that you wouldn't be able to measure a difference. If the wheel can't pull a significant enough amount of air into that gap when it's in still air, how would one expect for any to be pulled in there when air is flowing back across the frame?

You know...taking a look at that first flow image again...I wonder what the flow would look like if the space behind the seatstays was filled in with a tapering shape that continued to follow the curvature of the tire? Hmmm...now where have I seen something like that recently? ;-)

All that said, I'm willing to be convinced otherwise. Just "show me the data"...and the most important data in the end is how it stacks up overall to other TT/Tri frames. If it's as fast or faster than some of the other top end frames, who cares how big the gap is! ;-)

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http://bikeblather.blogspot.com/

"I have a power point presentation (from Look France) that i'm trying to convert for the masses. It outlines the steps they took to design what they feel is a top level Tri/TT frame. There is plenty of empirical data so hopefully I can get this going soo."

Just curious if you ever got the powerpoint presentation converted?

That black cap is, I believe, the cable housing stop for the derailleur cable. One on each side of the frame.