That may be realistic. The Cd of a flat plate is 30X higher a good aerofoil. Does a downtube have more than 30X the frontal area of a FD tab? Probably somewhere around that number. So not exactly out of the realm of possibility on a first order approximation.

I think that it is more of a comment of how little drag the downtube generates, that the FD tab being a large amount of drag. The downtube gets a nice long airfoil since it is angled, so it is very low drag part of the bike.

Those fhing with a frame isnt unique. Eddy Merckx did that in 2012

https://www.youtube.com/watch?v=0J2mfi2iKoI

Maybe this was covered already and maybe this is a dumb question, but how do you mount your water bottle on a split downtube? Seems like in the picture everything would be at angle.

The split downtube may help prevent separation at high yaw, kind of like a slat or flap on a wing. Even that might be dubious though considering they're parallel to each other..

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I like analyzing things - http://engineeringfitness.org

I agree with you so I can only guess that the bosses weren't designed for a standard cage.

Given that part of the marketing for the bike is a native BTA solution and bosses on the seat tube they may well have a very specific storage option in mind for the down tube. A custom solution may also blend in more aesthetically with the split down tube but I'm struggling to imagine what it will look like.

So if you use both the bosses on the downtube, would it not defeat the purpose of a spilt downtube because you essentially cover it with a bottle?

Air would probably still go in and then not be able to flow through?
Would love to see win tunnel testing for this vs. any other established tt/tri bike.

The only "new" parts are the storage from what I can see. The frame has been around since last year. Closer view of the split on pics here: https://www.bikerumor.com/...ke-splits-time-road/

Air won't go in unless it's also coming out.... not necessarily via a direct route, or from front to back, and almost certainly worse than a simple single tube with a bottle on the back.

Personally, I can't see any engineering or aerodynamic merit in this design.
It appears to be complication and weight increase for the sake of it.

Hasn't it been established by now that a downtube bottle is a bad idea? Bottle between the arms, bottle behind the seat is all you need for racing, and the aero doesn't matter when your training.

This. But it made me think of the Colnago Bititanio. Beautiful bike and I still lust after one. The Carbitubo was ugly.

https://www.bikerumor.com/...ne-caliper-one-disc/