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Our lightest construction method uses an exclusive unidirectional prepreg with a very low fiber areal weight. A variable thickness nipple bed reinforces key areas around the spoke holes, eliminating excess material. A blend of Toray T700 and T800 offers the weight saving benefits of T800 carbon without compromising the strength or stiffness of the rim.
What Are the Ultralight Carbon Bike Rims?
If it isn't clear from the name, the Ultralight are the lightest rims available from Xyz Carbon Wheels and for that matter, some the very lightest available on the market. Despite what you might think, the Ultralight does not refer to a particular carbon rim, but rather a construction process. We'll talk a lot of exactly what this process is later in Xyz Sports, but the short version is that Ultralight carbon rims are built to be as light as possible by using a blend of Toray T700 and T800 carbon, a new prepreg, and a new layup. The result is that each rim built using the Ultralight construction process drops anywhere from 30-100g compared to the same mould using our standard rim construction. So far XYZ has launched the RIM-A930S 29" MTB XC carbon rims (265g), the RIM-A935S 29” MTB XC carbon rims (280g), the RIM-D20S carbon road clincher tubeless rims (270g), and the RIM-D50S 700c carbon clincher rims (380g), ect are using Ultralight construction, but as we continue to develop the process and update our lineup, more and more rims will become available with Ultralight Construction.


New Construction Process
We modified three main processes in our construction to make the Ultralight carbon rims as light as they are:
1) We used a blend of Toray T800 and T700,
2) We used a lower FAW (fiber areal weight) and new preg and,
3) We used a new layup design at the nipple bed to reduce the amount of material needed.

As we were saying, the flyweights rims are built using a mix of Toray T800 and Toray T700 carbon fiber. What does this mean? Most of the rims that we build and, for that matter, that anyone else builds use exclusively Toray T700. The reason for that is quite simple; T700 is a little heavier, but far more robust than a Toray T800 rim. A rim Toray T800 is would be far too stiff, because of that, be quite brittle and crack easily. However, for the past number of year we have been experimenting with using a blend of Toray T700 and T800 to build a super lightweight rim that is still tough enough to race on. The result of this is the Ultralight construction process.
One of the keys to the Ultralight process and what is largely responsible to allowing us to use Toray T700 and T800 in the same rim is our new Prepreg. The new Prepreg has a much lower Fiber Areal Weight and we can create a more adjustable layup. This means that the stress between layers is reduced and the T800 can be used without creating the stiffness problem that typically comes with building a Toray T800 rim.
Another feature of the Ultralight construction process is a new nipple bed layup. On the ultralight we build up the layers differently depending on what the spoke hole drilling is going to be. The layup takes quite a bit longer to perform than our standard layup, but results in those no compromise marginal weight gains that we wanted out of a race wheelset.

Strength and Testing
You're probably wondering, are these super light XC rims strong and stiff enough? The short answer? Yes. Although they are intended as a race wheelset, one of the main priorities with the Ultralight was to make a race oriented rim that could handle whatever even the most technical XC tracks through its way.
Not only did we use lab testing to make sure that this was the case, but we also sent some of the first Ultralight rims to riders that are more likely to be found racing Enduro than they are to be found on a Cross Country course and told them to ride them the same way they’d ride their Enduro wheels.
We even had one of our 175lbs test riders drop the pressure far below what we would recommend and rip down a double black diamond trail just to check the Ultralight impact resistance. Despite bottoming out the rims on rocks numerous times, he didn't break it.
Obviously that kind of riding isn’t recommended for these, or any rims, but we wanted to see what type of real world forces our Ultralight XC carbon rim could handle. The answer? A whole lot more than you’ll find on a cross country trails.


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