The reason that you dont see super deep frame sections is because UCI regulations limit the aspect ratio (width to depth) that is allowed with frame tubing. I believe it it limited to 4:1 but am too lazy to look it up.

Prior to UCI regulations you had a lot of super deep non standard frames, think Lotus, Corima, Pinarello and the Australian Institute of Sport superbikes.

I remember the Trimble frames, dont recall aerodynamic data but supposedly they were a crosswind handfull.

KR

So because of UCI, the only place we might expect to see inovation in the frame area is in something like RAAM?

Very strange that the UCI is so worried about frame aspect ratios.

We should also see it in triathlon, but.....that's where the big marketing department comes in. Cervelo/Trek have them, B9, Softride, Titanflex don't.

Given the huge number of Ironman competitors who arent bound by UCI regulations and the fact that most USCF categorized racers are also unaffected it is surprising you dont see a lot more Lotus style or beam style bikes out there in triathlon or TT's.

The large manufacturers use the pro tour teams for marketing purposes so their bikes have to be UCI legal. I guess it would be too expensive for Cervelo or Trek to make a non UCI legal bike. It is good to see Blackwell making non UCI legal forks for example.

KR

How much do you think the manufacturers of bikes labled as Tri bikes depend on the Time trial Market to sell bikes too, in their profit margins? Does this influence design?

Although the majority of time trials are proabably not governed by the UCI rules, time trialists are probably more awear of the types of bikes used by the UCI pro's which may effect their buying decisions?

I would say that there is a huge influence by what pro tour teams use. That is why Softride are no longer making bikes and other companies like Titan Flex and Cheetah are very much niche makers.

That doesnt mean that it makes sense.

KR

The fully faired frame mentioned earlier was done by James Trimble (not to be confused with Brent Trimble who did a very cool monocogue carbon mtn bike in the early 90's) the pictures below were lifted from http://www.mountainbikes.net/.../Trimble_Aero_91.htm



check out the access door:



I'm not sure how these would compare to modern day bikes, but I know that at the time they were less aero than the Zipp 2001 frames, but at the time nothing was as aero as a 2001 (even the Lotus). I'm not sure how anything modern compares as we haven't done any further testing on frames since 1998 when we quite making them.

josh

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"...but at the time nothing was as aero as a 2001 (even the Lotus). "

No disrespect Josh but you are incorrect. Unless you are talking about some strange condition with a yaw angle the Lotus Superbike is unquestionably more aero than a 2001. I have both and the Zipp 2001 is thick and bulbus compared to the thin and sleek design of the Lotus. Further the Lotus is the only bike to produce a sub-pound of drag.

Unless you are talking about a custom superbike (think Brusford) there isn't anything that can touch a Lotus. Anyone who says otherwise is either misinformed or trying to sell you something.