Some Initial Impressions on the 2009 Kestrel Airfoil Pro

posted Aug 27, 2009, 6:04 AM by Donald Vescio   [ updated Sep 12, 2011, 8:10 AM ]

I’ve always been a huge fan of Kestrel’s products.  Several years ago, I used to TT on their Talon model and had great results; my only complaint with this specific frame was that its stack was too tall and its reach too short for it to fit me properly.  As a result, I drifted over to long and low frames, first settling on a Cervelo P3, and then a P3C.  I’ve been racing the P3C for the past three years.  I normally will post the fastest bike times in most events and will average around 30 mph on a flat course (putting me in the hills is a whole ‘nother story, though!).  For me, a frame has to perform well in order for me to use it.

Cervelo makes a great product and their designs have proven reliable and fast.  But as nice as my P3C is, I still missed the ride of my old Kestrel—there was some intangible quality to it that kept making me go back and rebuild the bike to try to make it fit.  I finally swapped Talon over to one of Elaine’s clients to put an end to my dithering.

So when I saw that Kestrel redesigned its Airfoil for 2009, I was intrigued.  I compared stack and reach with my P3C,  realized that the 52cm Airfoil would be a perfect fit, and took delivery of the frame last week.  What I want to do is share some of my initial thoughts about the 2009 Airfoil for now and later post specific data on its performance after testing.

As much as I liked the Talon, it had one design aspect that I loathed—it was one of the most difficult frames to run cables that I’ve ever seen.  One the cables are run through the frame, future replacements should be relatively easy, provided that one remembers to run housing through the frame prior to pulling the cables out.  If this step is missed, then assume that you will  spend a good amount of time fishing cables through the down tube.

But for 2009,  I would rate the Airfoil’s internal cable runs as one of the easiest that I have ever used.  Assembly of the frame was fast and easy, requiring no special accommodations or preparations.  The bottom bracket insert was properly threaded and faced; the front hanger even has an angle adjustment to fine position the derailleur.    The frame uses an internal headset based on what appears—unfortunately—to be an emerging standard: 1 1/8” top bearings and 1 1/4” bottom.  This design limits the availability of aftermarket forks, if one decides to try a different front end.  The Airfoil accepts either as standard 27.2 round seat post (with the use of a drop-in adaptor) or Kestrel’s aero post.  While Kestrel’s post is relatively heavy compared to some other models, it is remarkably stiff and has the best saddle clamping system of any frame out there—it has none of the fussing and worry associated with Cevelo’s or Felt’s seat posts, for instance, and the ability to use a standard round post is a great option in the event that some catastrophe occurs at a race location.  The seat post is clamped by a simple set screw; there is a gap between the seat tube and the aero post when installed that could admit water, so I will want to work out a solution for this in the near future.

The frameset itself is fascinating and the most notable aspect of its design is the absence of a seat tube.  Its top tube has a flat top and bottom profile and is nicely faired by the head tube; the down tube has a sharp trailing edge, as do the seat stays.  The down tube flairs significantly between the front derailleur mast and bottom bracket—it is massive. Give that this location already is aerodynamically compromised by spinning cranks, pedals, etc., I don’t anticipate that there will be a significant aerodynamic tradeoff for the stability that Airfoil’s bottom bracket should offer.  Above the derailleur mast—the bulk of the down tube—the profile is quite thin and appears well-shaped.    

The stock Kestrel fork has plenty of space in it crown and between its legs, looking like it should be a good match for my preferred front wheel, Hed’s H3.  Because of the bottom 1 1/4” bearings, I will not be able to swap in my Blackwell Time Bandit fork, which is the fastest (albeit non-UCI legal) fork that I’ve ever used.  The current fork, though, appears to have a solid profile and certainly is stiff.    The only other quirky design feature is that the Airfoil uses horizontal dropouts, which came as a big surprise to me.  Horizontal dropouts are great if one wants to be able to position a variety of wheel/tire combos close to the seat tube.  But given that the Airfoil has no seat tube, I am kind of baffled by this element (and, to be honest, I was looking forward to the simplicity of vertical dropouts).    After more though, I have reconciled to the horizontal dropouts by recalling an old Gios Compact that I used to have, remembering how I liked having the ability to adjust the effective length of my chain stays. My current build of the Airfoil has the rear wheel positioned all the way forward.

I took my first ride on the Airfoil last evening and was extremely pleased with its ride.  It seemed to have a very slight vertical compliance that made it a bit more comfortable than my P3C, but the biggest difference was its stiffness—this frame is, by far, stiffer and more lively than my P3C.  I did collect some initial throw-away data last evening and I can say that the bike is fast, too, though I want to run through a series of extended tests to make a final determination.

Before: Don plugging away on a Kestrel Talon