Interbike - Felt AR

One of the things I looked forward to at Interbike was a look at all of the aero road bikes out there. I figured that there had to be a bunch introduced. With the announcement of the Felt AR, I thought that other companies would follow suit. With the AR introduced so late in the season, it would make sense for competitors to unveil similar framesets at the fall season IB.

Alas there were no framesets out there that met my criteria for an "aero road bike" - wind tunnel tested framesets designed to give an advantage to racers at any speed where wind resistance became a factor. I looked to a couple places to "judge" a frame - the fork/downtube area, the seat tube, and the downtube. All of these areas receive a lot of attention with TT bikes, so it follows that they should receive attention on aero road bikes.

Felt, it seems, is the only one out there with a truly aero road frame. I'd judge some other frames to be close, but not with the most up to date aero refinements.

Without further ado, my take on the Felt AR.

Rear quarter shot. Frame looks squashed from this angle.

I took this picture to capture just how thin the bike is when viewed as the wind sees it. The downtube especially loses a lot of width, something not obvious in the normal profile shots.

Bottom bracket. Cables run inside the frame.

The bottom bracket area has to retain some stiffness, so Felt increases the width of the frame until it appears pretty much normal just above the BB shell. A friend rode this bike (with the new mechanical Dura Ace) and raved about everything. Even on a very large size (he rode some enormous size - like a Magnus size) the frame exhibits adequate stiffness. I'd want to try one too, just to see, but if the rigidity is there, I wouldn't see any compelling functional reason not to use the frame. Yes, cost, yes, sponsorship, but any "logical" reason?

None.

To run the cables inside, you have to insert them somewhere.

The top tube, just behind the head tube, is a popular spot to insert cables. With the stem already disrupting airflow, this is a great spot to stick vertical, unaerodynamic cable housing. It has to be a low stress area too - I don't recall manufacturers welding reinforcements to the top of the top tubes on BMX bikes, for example.

Fork to downtube relationship.

One of the areas pinpointed in time trial frames is the fork-downtube area. Trek came out and declared it relatively important in their latest TT frameset design. Felt deals with it by dropping the downtube so that it allows airflow to smoothly come off the fork crown.

The downtube - tire detail. The tubing is so smoothly seductive.

The downtube continues its air flow smoothing effects by following the front wheel profile. Apparently this spot is where the air really separates from the tire, and the little notch helps pick up the turbulence and gives it a smooth surface to follow.

A blurry rear stay.

Although not a clear picture (a problem apparently occured with the nut that holds the camera), it's apparent that the rear seat stay is faired in pretty well. No lumps presented to the wind. Well, not until you install the rear brake.

And there's the problem.

With all this aero frame stuff, suddenly the components look, well, un-aerodynamic.

I think that'll be the next component group thing - more aero brakes, more aero derailleurs. With normal road frames going aero, there'll be demand for more aerodynamic components. Hanging a big lunky brake on a smooth, sleek fork simply won't cut it anymore. Nor will the big, lunky bottles.

Here's my prediction for today:

I figure in the next few years we'll see a lot of aero bottles (with a somewhat standard cage shape for versatility) and narrow profile major brand (Shimano, Campy, SRAM, FSA) brakes on aero road bikes in mass start road races. Think of a reincarnation of DuraAce AX, but this time the components will be light, functional, and stiff.