The bike industry is a lot like like the national press: Nothing is whispered; everything is shouted. If there isn’t any big news, elevate the small news to big. Whether it’s philandering minor congressmen, all-out war or anthrax, the urgency in the rhetoric and the type size of the headline is the same.

The difficulty is in being able to discern what really is important. Having attended the Interbike show earlier this month it was obvious to me what road bike makers thought was big: carbon. Not necessarily carbon bikes. Carbon parts of bikes, and carbon parts on bikes. What I mean is, yes, there were carbon seat posts, handlebars, cranks, stems and saddles. But there were also aluminum and titanium frames that featured carbon subassemblies inserted here and there.

The “here” and the “there” were of a theme: forks and seatstays. We know about the forks. The reason I wanted to road-test this bike was because of its arse-end. Is there really anything to this carbon seatstay thing? Is it peace in the Middle East? Or is it just a flippy-flapping congressman?

I chose to road test the 2002 Yaqui Carbo because it is precisely the same bike as the one I’ve been riding for quite a few months, with the exception of the carbon stay arrangement. The way much of the world of road bikes has decided to go is toward a unified, monocoque, monostay, wishbone thingamajig––basically a fork turned around backwards.

If you’re a bike manufacturer, there are three reasons why you’d want to put this on your bike. First, it looks sexy, and if you can’t figure out what else to do that’s new, you can do this. Second, you’re pretty sure other bike makers are going to use carbon seatstays, and you don’t want to get outsexed by them, so you do it for defensive reasons. (This is the single biggest reason there are so many of these out there for next year.)

Then there’s the turd reason––as the Yugoslavian (San Marcos, California-based) maker of Yaqui bikes will sometimes say, without meaning anything by it––and it’s this reason on which I’ll focus. It’s vibration absorption. Basically all metals vibrate the same way, but carbon doesn’t follow this pattern. So if you’ve got an aluminum or titanium bike, you could put this carbon stay between the rear axle and your saddle and the vibration will not get past the stays.

Vibration is the name of the game here. You can only make this comfort argument––it seems to me––if you bring the discussion back to vibration. I say this because the other potential shock absorber––vertical compliance––is not at issue here. By "vertical compliance" I mean something like the springs in your car. A Softride’s beam is a good example of vertical compliance. That's the only way you want your bike to be compliant. Horizontal compliance means your bike sways side to side (or front to back, I suppose, which is what you'd get if your headset was loose). Movement along those two "horizontal axes" is not considered desirable.

There aren’t many places where a bike can become compliant in the vertical plane. Perhaps in the bend of the fork blades, especially in an older-style steel fork. You get some vertical compliance in the tires, perhaps a bit in the wheel, certainly in the saddle rails and in the padding of the saddle itself. But seat stays are positioned in a fashion in which there is no compliance possible because the force of a bump travels up the length of the stay, not across its width. The only possibility for compliance would be in curved stays, as is the case in some models of Litespeed and Serotta bikes I’ve seen. Or if you put a shock absorber in the stays, as is the case with Moots’ YBB suspension system, in which the chainstays are the “spring” and the YBB is the damper.

As for these carbon monostay arrangements, there are two makers who are trying to get some compliance into them by curving them like the titanium-stayed bikes mentioned above. One is Reynolds (the bad picture at right, taken at Interbike, will give the reader some idea of what Reynolds is trying to do with its monostay), the other is Litespeed. Their carbon unistays are arched, and it’ll be interesting to see what applications they're used for. I notice––if I remember right––that the arched stays are in Litespeed’s ti bikes, but not in QR’s aluminum bikes, which also feature carbon unistays. (Litespeed owns QR.) There are two possible reasons for this. Either it’s just that Litespeed wants this curved-stay feature for its own brand or––in an act of brilliant foresight––it may realize that adding compliance (allowing an arched stay to bend) might be the death of an aluminum bike. What I mean is, if an arched carbon unistay really works––if arching the stay really does allow for compliance, like an archer’s bow––that means the chainstays will have to bend as well. A titanium chainstay will bend, to a point. An aluminum chainstay won’t, or to put it another way, it will, but not for very many cycles.

Most of the carbon unistays don’t have an arc in them, and I believe that’s a good thing, if such stays are meant to go into aluminum bikes as well as titanium. Therefore, we’re back to the real reason the stays are going into these bikes, which is to damp or absorb vibration. Does it really work?

By riding the Carbo it’s hard to tell. The bike was very comfortable to ride, but then so was––is––my Yaqui Mariola. The Carbo, like the Mariola, is comfortable mostly because it fits me perfectly, and that is because Yaqui’s Ves Mandaric understands tri geometry. It’s also comfortable because it’s got Easton’s Scandium tubing in it. I doubt there’s anything magical about the chemistry of the alloy, other than the fact that the alloy is so strong that the tubes are both narrower and thinner. Why does narrower, thinner tubing feel more comfortable? I couldn’t tell you. It just does––at least according to the signals my hind-end transmits to my brain.

The ride was sufficiently close to that of my Mariola that I think the only way to actually tell whether the Carbo was more comfortable would be to have both bikes out in the same place at the same time and ride them over the same stretch of road, probably switching the same set of wheels back and forth. Perhaps that's the test that will come next, in which case everything down to the same brand and pressure of tire will have to be identical.

Here’s the interesting thing. There is one real benefit to the Carbo––irrespective of the fact that whenever I hear the name of this bike I think of the word “party.” (It means “carbon” in Italian.) I doubt whether anybody thought of this when they were dreaming up the carbon unistay feature. The fact is, regardless of what it does in the vertical plane, it is mambo-stiff in the horizontal plane. This is welcome because the one thing about aero-tubed bikes––especially legitimately aero tubes, like those the Carbo uses––is that they aren’t going to be as resistant to lateral stresses as would their round cousins (i.e., they're compliant in the horizontal axis). It has always been assumed (at least by me) that there wasn’t really anything you could do to seat stays to aid in lateral stiffness––all that work would have to be done by the downtube, chainstays, and seat tube, in that order––so you might as well make the seat stays as light and insignificant as possible. As a bike maker, that’s what I always did. And that’s what I’d still do, if the stays were made out of aluminum or steel.

But the unistay that Mandaric has put in his new Yaqui is an entirely different animal. It’s robust. It ain't gonna move. It gives the bike, I believe, an added amount of lateral stiffness, which might not be necessary in a round-tubed road race bike but is a nice gift to a bike with a downtube only 26mm wide across its minor diameter.

So, simply put, I found the Carbo an absolute dream to ride—and perhaps it's my imagination, but some of the “metallic” sounds my Mariola made upon shifting aren’t there in the Carbo. Maybe some vibration is being absorbed.

There are some bike makers who have chosen to eschew the carbon stay craze, and I frankly can’t blame them. Cervelo has yet to jump on board, and this company has less reason to than others to go to a carbon stay. Cervelo also obviously makes legitimate aero tubes, and it makes its tubes in such a way that it doesn’t have a problem with lateral flex. I’ve always found the Cervelos I've ridden plenty comfortable––perhaps because its stays enter the seat tube down further toward the bottom bracket, not jammed right up your arse.

But for the right bike I can see the reasoning behind the carbon stays. I just wonder how many bike makers are thinking through all the ramifications of the carbon unistay feature––whether they’re using it for the right reasons––and consequently when and whether they’re choosing the right carbon stay for the bikes they make.

The Carbo is the newest in the Yaqui lineup, and it will cost $1,950 for frame and fork. The fork Yaqui chooses for this bike is the Reynolds Ouzo ProAero, although Mandaric uses what looks to me like a larger, non-arched––and perhaps better suited for its particular bikes––unistay than the one Reynolds makes. (I like the Reynolds stay for titanium bikes.) The Carbo can be purchased in a stock size or custom-built to the customer’s geometry and specs. It can be sold as a complete bike as well, with either Campagnolo or Shimano components. A Dura Ace-equipped Carbo with all the bells and whistles will go for $3,695, or $4,150 with either Hed3s or Zipp 404s.

Yaqui––made by Mandaric Cycles––can be reached at 760-736-4427.

(OTHER TRI BIKE REVIEWS)