Triathlon - What's the difference in the various Zipp disc wheels?

So there is a Zipp 900, a Sub 9 and a Super 9. The 900 is the lightest at a claimed 936g (tubular) - and also the cheapest. The other two wheels are much the same price - nearly $500 dearer than the 900 - and slightly heavier (998 and 995g respectively). So why would you buy the Sub 9 or the Super 9?

The sub 9 is essentially a 1080 rim with a 900 disc core in the middle. This is done for aerodynamics, there is not as much of an aerodynamic penalty when using a 23mm tire and it is more comfortable because the bulge area has a little bit of give whereas the 900 is a solid core so more harsh.

The 900 clincher is actually more like the sub9 than the 900. It has an 808 clincher rim with a 900 center core. It's the only clincher disc that Zipp does.

The super 9 is similar to the Firecrest wheels in its technology, Zipp has even said things along the lines of "it is the original firecrest before we created that name." The Super 9 is stiffer than the 900, and because of it's wide rim it is more aerodynamic, again particularly with a 23mm tire.

So, a lot of long course pros prefer the Sub 9 over the 900 or the super 9 because of the comfort. Short course racers tend to use the Super 9 more often because of it's stiffness. The 900 is the lightest but you should run a 20-21mm tire to get the most out of it aerodynamically.

Finally, depending on your bike you may choose a different model. Because of the width of the Sub9 bulge, it doesn't fit in some frames. Because of the Super 9's wide brake track it may be a difficult fit on some of the newer less adjustable proprietary brakes. The 900 has no issues with any bikes that I'm aware of.

Thanks for the detailed reply!

Your welcome.

One other thing I would note if you're considering the Zipp 900, is that many companies sell a relabeled version of the undimpled 900. American Classic, Rolf Prima and a couple others have their own versions. The American Classic is another $200-400 cheaper than the Zipp 900 and has essentially the same characteristics as the current Zipp 900 but without the dimples.

I'm guessing that your in Australia, which probably means pricing and availability may vary for you.

Your welcome.

One other thing I would note if you're considering the Zipp 900, is that many companies sell a relabeled version of the undimpled 900. American Classic, Rolf Prima and a couple others have their own versions. The American Classic is another $200-400 cheaper than the Zipp 900 and has essentially the same characteristics as the current Zipp 900 but without the dimples.

I'm guessing that your in Australia, which probably means pricing and availability may vary for you.

Yeah thanks. I have actually just purchased a used Zipp 900 (tub) - seemed like a good deal for $1000 (PBK are $17XX). I plan to run a 21mm tyre, same as my front 404. I wasn't aware that other companies re-label Zipp products and sell them as their own.

Pls help me guys... i just got my zipp900 clincher version... but i have had problem inflating it... i was ask by my mechanic to hold the adapter on the wheel in one hand and use the other to pump it... how the hell will i ever reach 100PSI this way? i also found out that guys using CO2 on this wheel face a problem of the CO2 gas getting too cold on their finger and had to let go the grip...

So what happen if i had a flat on road while out riding alone???

Any help, tips or advice on better ways to inflat this awesome wheel are welcome.

Thanks

Hey Stonely,
First, the C02 thing really shouldn't be a problem(its no different than flatting on any other wheel), and if it really is, I guess get one of these: http://www.google.com/products/catalog?hl=en&biw=1280&bih=539&q=co2+bike+tire+inflator&um=1&ie=UTF-8&cid=12256309113412070197&sa=X&ei=MwPKTarMDM7TiALNifWpBQ&ved=0CEIQ8wIwAA#

that way you don't touch the cannister, though you really shouldn't have problems.

Second, I've pumped one handed while holding the adaptor up to 100psi, it takes practice. But usually, if you need it, you are at a race and there should be hundreds of helpers around. Everyone I've ever asked is more than happy to help.

Third, if you need, this is a locking silca disc pump adaptor: http://www.coloradocyclist.com/product/item/SILPXQF9

Another thing to consider with a rear wheel in terms of aero performance is the frame down tube. With a front wheel the air flowing onto the tire and rim is clean and free of turbulence. This is where the profile of the rim just behind the tire bead is important for attached flow and hence the generation of aerodynamic side lift.
With the rear wheel the air flow is disturbed and hence will already be separated and therefore the side lift is less. Essentially the wheel (thinking of it as a wing) is stalled, but you still get the sail thrust effect by virtue of the sail area. I would guess that disk wheels are wind tunnel tested without the bike frame and this makes the results invalid for the real world. Also those dimples don't make any difference to drag. They are used on a golf ball to induce flow separation and hence reduce the drag for a ball, a disk doesn't have the same flow pattern and therefore it's just a sales gimmick.

I am also looking for a rear disc. The big issue I have is trying to keep a close brake pad gap (since the rear brakes are not adjustable, BMC TM01 with Campagnolo levers) whilst avoiding brake rub.
Any one have any experience with the stiffness of different disks?