I wrote last week an observation of mine, which I can’t get past, about CADEX wheels. The implications are starting to sink in, hence this update. CADEX is part of the Giant group of brands, and so far the brand’s products of which I’ve become familiar are its high-end road and aero wheels and tires. Specifically, CADEX makes a 42mm road (which has been liberally ridden on gravel as well, regardless of its intended use case) and its 65mm aero wheels. And then there is its 28mm road tire.

I’m sure CADEX hoped I would recognize the typical value proposition that attach to skinny tired road/tri products: aerodynamics, ride quality, puncture resistance, weight and the like. And I will. The more that I ride around on various wheels, the more I learn, about CADEX and the other wheels and tires I ride the more I’ll write. But I noticed something unprecedented about this product, as you know if you’ve been reading my articles about CADEX: They don’t leak down. They hold air like a tire with a butyl tube. And this is before I put any sealant in there.

This is just not normal, and it’s abnormal in a good way. I explained why I felt that this was important to the parent brand Giant: Because it can send a tubeless system tubeless, rather than sending a tubeless system with a tube in it, forcing the user to switch the system to tubeless.

Last week I wrote that it’s the wheels. This is how Giant has achieved no-leak tubeless. I spoke too early. What I wrote is that Schwalbe Pro One tires also don’t leak down on CADEX wheels. However, as I’ve let these systems stand for a week – as opposed to only 3 days – the CADEX tires remained inflated to a high pressure (within 3 pounds of the 75psi I blew in there a week earlier), whereas the Schwalbe tires did eventually lose more pressure on the CADEX wheels. Therefore, I repent of my earlier conclusion. While Schwalbe tires are a very good option for CADEX wheels, there is some magic about the CADEX complete system. Let me tell you why I think that might be.

The catapult that will launch tubeless into ubiquitous use is the ETRTO standard for tubeless bicycle wheels, released in 2019 (Greg Kopecky wrote about the 2020 edition of ETRTO standards for bike wheels). The ETRTO is the organization that sets standards for all wheels in Europe. Not just bike wheels. Tractor, truck, airplane, motorcycle, automobile wheels. Maybe not wheelbarrow wheels. But just about everything else. There is another standards organization, ISO, but the ETRTO has so much power over what manufacturers do that it is the de facto standard. In fact, what I’ve heard is that the ISO is prepared just to stipulate to the ETRTO’s design standards for bicycle tubeless, which renders any question moot.

Note that I write “wheels.” The ETRTO doesn’t publish standards for tires; but this places an even tougher burden for tire companies. Wheel makers know exactly what to make. The ETRTO publishes the standard. Tire companies must manufacture to the wheel standard, but are given no guidance. Certain brands have taken it upon themselves to test tires, and to form their own tests, and ENVE is at or near the top of the heap as regards this. Here is ENVE’s lab, and in my opinion what the ISO could do is look hard at what ENVE is doing, with an eye toward adopting some of its tests as industry standards.

That drawing above is my own rendering, not to scale, of the design constraints placed on wheel makers, as regards hookless rims. In a future article I’ll write about why hookless is the thing, because of how much better you can make a wheel if you begin with a hookless design. Within the past year our Greg Kopecky covered this pretty well. The larger point is this: You can now design your products specific to a standard. Let’s take something as simple as a tubeless valve stem. The ETRTO has told all makers exactly what the contour of the rim well is to be. When I look at an aftermarket valve stem for universal deployment, such as that made by Stans No Tubes, that will work. But it isn’t designed (as well as I can tell) to work specifically for the ETRTO standard.

One of the reasons I give for why I think the CADEX system holds air so well is the extremely snug, precise, fit of its valve stem into its rim well. there may be some secret sauce here, in the density and elasticity of the rubber used in the valve stem, and in the sealant tape. I don’t know. (Yet.) But the contour is known, assuming CADEX is following the ETRTO standard.

There are implications to this. We can start using better valve stems in our wheels. Nobody to my knowledge is advertising a valve stem made in specific to 2019 (and thereafter) ETRTO design standards. I would be a lot more likely to buy that stem if I knew this stem was designed for the ETRTO standard, because most of the wheels I’m riding now are built to this standard. This makes life very easy when I know that both a wheel, and a valve stem – regardless of who makes each – is in compliance with this ETRTO standard.

It doesn’t stop there. Now tire companies can make tires specific to the ETRTO standard, and for rims with hookless beads. This is what Schwalbe did with its 2019 release of the Pro One and the Pro One TT, and I presume this is what CADEX did as well. If you think about it, this should make it very easy to make a wheel/tire system that honors aerodynamics. Look at the image of a CADEX 65mm aero wheel, with a CADEX 28mm tire mounted on it, and tell me if that doesn’t look pretty darned aero to you, at least as regards the meeting of the wheel and the tire. That hourglass contour is gone; now it's just a smooth mating, tire to wheel. For decades I was a confirmed tubular tire user, for racing, and no tubie glued to a wheel ever looked like this.

I had a discussion with the folks at Zipp last week, and they confirmed that they are wholly on board with ETRTO compliance, and the 303 models released within the past year – the Firecrest and the S – are both hookless and ETRTO compliant. Zipp has embraced this notion of tire design wedded to the same spec, and told me that not only their own tires, but those of Pirelli, Schwalbe, Goodyear and Panaracer affirm compliance with Zipp wheels. The one tire company that – according to Zipp – has confirmed Zipp non-compliance is Continental. I have not spoken to Continental about this.

But when I consider Zipp’s posture on this, here is the train of thought. Zipp makes hookless wheels that conform to 2019 ETRTO compliance. There isn’t a lot of wiggle room here. You see the tight metrics in the ETRTO specs. Can you be Zipp non-compliant while remaining hookless ETRTO compliant? Perhaps, but Conti will need to tell me how. The point here is that if CADEX, Zipp, ENVE and other wheel brands are making rims that comply to this standard, and as more and more wheel makers make new wheels that conform, tire companies that don’t make tires to this standard appear to me to have a smaller and smaller use window.

ETRTO hookless specs give tire makers a golden opportunity to build a tire that works with every new wheel – is aerodynamic with every new wheel – because there are now constraints to how how those wheels are made.

It is my uneducated – but observant – guess that one reason Schwalbe tires work pretty darned well on CADEX wheels is that Schwalbe built its latest generation Pro Ones to be ETRTO compliant, and they affirm their tires are Zipp compliant, which means they are pretty darned likely to be a good match for CADEX’s wheels.

But they are still not quite as airtight on CADEX wheels as are CADEX’s tires. More on the in a future installment, as my workshop investigations proceed.