Hey guys, there is a lot of conjecture here, so I will tell you our position on some of these things, hopefully it will help.
The weight/aero debate will forever rage, but my personal feeling is that for most people aero will almost always triumph. The 202 is an incredible hillclimb TT or road racing in the Alps wheelset, but is designed for road racing, and not Tri. The reason is that a roadies need the weight and inertia advantage to make very high wattage intense efforts at key points in a race. Looking at a most any Tour stage in the Alps, the 202 is disadvantaged to a 404 for more than 80% of the course, but will be advantageous in making or following an attack at a key point of a climb. In actuality, the 404 aero advantage offsets its weight over a 202 up to about 7-8% grade depending on rider output. So even in the hilliest of courses, the 202 at best will only be advantageous in very specific terrains. Having said that, however, in road racing, that attack coming out of a hairpin turn onto a 12% section of the climb can be critical, and just 1-2 watts of efficiency gain suddenly becomes a few seconds in a hundred or so meters. This can be pivotal tactically in this type of event. In triathlon, the power requirements are much more stable throughout an event, and will almost always favor the more aero wheel. A rider may lose a few seconds over a very steep pitch, but likely has gained many seconds up to that point and will continue to gain many more seconds after that point. When we run the computer models of the Alpe stages, the 404 always overcomes the lighter wheelsets, generally by a few minutes or so, and thus we have always recommended the 404 depth wheels, but after working with CSC last year, and looking at the power requirements on various stages, we have begun to understand exactly what these guys need, and realize that our computer models more accurately represent a TT over the stage, but do not account for tactics, attacks, or other factors.
As for rim design, our patents on rim shape help to insure that our rims behave as if they are much deeper than they are, so many comparisons are hard to make to other rims. The 202 is in fact similar aerodynamically to the old 340 rim shape, which was that of a 'V' and the new 303 is comparable to the original 440 rim which was a 'V' shape. Compared to 'V' shaped designs, the 38mm 303 behaves similar to a 'V' shaped 55-58mm rim, and the 404 behaves similarly to a 75-80mm deep 'V' shaped rim. In all, the difference between a 202 and 404 at 30mph on flat land is between 10-14 watts depending on wind angle, and the advantage of a 202 to a 404 at 8% grade at 15mph is roughly 1-2 watts (the two are equal at about 7% according to computer modeling). The real beauty of the Zipp rim shape is that the rims maintain their aero advantage when used with tires wider than the rim (but less than 105% of the width of the bulge), which is the real difficulty with 'V' shaped rims. This allows you to have solid aerodynamics with a 21 or 22 mm tire, whereas you are losing 10-15% efficiency with one of these tires on a 19 or 20mm 'V' shaped rim. This was the real discovery, and in my opinion is the real meat behind the Zipp rim shape patent, especially for roadies who prefer the better grip of a wider tire, and ironman distance triathletes who can use the additional comfort of a slightly wider tire.
Lastly, I wanted to address the comment made about our hubs. I agree with woodenshoes that the AC hub is a great hub, but there is a tendency for people to think that the Zipp hub is not the most advanced hub on the market because they come in prebuilt wheels. We have spent the last 4 years designing and perfecting our hubs, here are a few facts that people tend to overlook:
Zipp makes all hubs completely in house, each designed specifically for the rims they are used with. So a 404 hub has spoke angles precisely for that rim, etc, and on a straight pull hub this is very important. Every Zipp hub is made entirely in the USA in our Speedway, Indiana facility. The Zipp hub uses 4 proprietary grades and heat treatments of 7000 series aluminum, all drawn specifically for our hubsets by Alcoa in Lafayette, Indiana, each type of aluminum and heat treat is specific to a particular part or function of the hub. Zipp hubs are manufactured on dual spindled lathes with live tooling, meaning that most every part can be made in one operation, removing tolerance stackup that occurs when parts have to be removed and fixtured in multiple steps. Because of this the bearings bores are more than twice as concentric and planar as with other manufacturing techniquea. All Zipp hub internals are turned on Swiss watch lathes, these machines were originally designed for manufacturing precision timekeeping components, and are generally only used to make precision aircraft fittings, bone screws and orthopedic inserts joint replacement. The incredibly high accuracy of these manufacruring techniques allows us to use much higher grade ball bearings and races, and results in hubs that spin with lower friction and increased bearing life, while weighing less than other designs. Zipp is the only company in the industry using Swiss made ball bearings, and the only company to use grade 10 balls, which are more than twice as round and 4 times as expensive as grade 25 balls which are the highest precision balls used in the bicycle industry otherwise. There are numerous other very nice hubs on the market, but we feel that we have the finest designed and manufactured hubsets on the planet.
Whichever rim, hub, or manufacturer you go with, my suggestion would be to prioritize aero over weight. If you do go with a 'V' shaped rim, you will need a tire either equal in width or slightly narrower than the rim, in order for the rim to behave to it's potential from an aerodynamic perspective, and if you go with the Zipp products, we recommend 21mm or smaller tires for the 202 and 303 wheelsets, and up to 22.5mm tires on the 404 wheelsets.
Best of luck
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