RCG36 Disc Wheels

carbon disc gravel RCG

We've entered the middle stages of the component carbon rim era. For us, disc brake market penetration has made us take a really long, really hard look at carbon rims and where they're going. The significant liberation of not having to deal with brake heat just plain makes it easier to build better rims. The supply market has shifted radically, with newer and different players taking over for more established ones. Evolution has happened fast, which creates opportunities (in both the good sense and the bad).

I don't want to bury the lede the way I do so often, so here it is: we've got a new carbon rim-based build series which we are calling the RCG36. RCG stands for "Road/Cross/Gravel," which are the uses the wheels are designed and perfectly suited to cover. The quality is as good or better than than a lot of the more expensive stuff we build with, all the business parts (including proper product liability coverage) work out, and the value is compelling. The rims are made in China by a manufacturer (yes, we're sure) that you're likely to have heard of, and to be blunt you can get rims from them yourself. We'll spare you the market's typical BS, but we feel like we're the brand that counts in this equation. That's as deep as we'll go there.

The rim specs are 700c, 36mm deep (hence the RCG36 part), 21.5mm wide internal, 28.5mm wide external, 420g/rim weight, tubeless ready, 100% disc specific, and symmetrical. The 36mm depth, for us, is primarily about wheel structure rather than aerodynamics. Many of the shallower carbon rims compress so much under tire load that the build becomes unstable. There is minimal tire-related tension drop with these.

The internal width is perfect for anything from a 28mm (which would probably say "25mm" on it) road tire to a 42mm gravel tire. Road tires work best with rims wider relative to the tire, where on gravel tires a bit of "muffin top" adds to the suspension you're getting from the tire, ensures that the tire tread works properly, and protects the rim. For cross, we've found that this width is ideal, and try as we might we could not burp them. The external width kind of follows the internal width, but if you're looking for that ideal tire to rim match, a 25mm Conti 4k or Vittoria Corsa G+ is just a hair narrower than the rim, and a 28mm version of either is just a bit wider than the rim. 

We're working with different 27.5" options now, which will be wider. Our thought is that a worthwhile 650b wheel is a complement to a great 700c wheel, not just a smaller version of it. 

The weight won't wow the weight weenies, but they are light, and their weight is appropriate. We expect that people will want to use these, and use them, and use them, and use them and use them again. We're very satisfied with the weight, and we don't want to compromise durability just to chase a gram spec. And it's easy to build a set of these that are markedly lighter than Zipp 202 rim brake clinchers. By weight category, they're climbing wheels. 

A perpetual quest for a great "mid ground" disc hub that offers something more than the OEM-level stuff at the low end and the expensive stuff at the top has ended with the Aivee MP2. To have one in your hands, you think you're holding a way more expensive hub, but they are very reasonable. We never loved their road hub geometry, but the disc stuff works great. The final gate was unlocked when they produced a center lock version (which are en route to us now, hence no picture). We looked at a bunch of 6 bolt hubs, and a lot had a lot of offer, but at the end of it we just much prefer center lock

Complete builds with CX Rays start at $1095, with all of our more popular hub and lacing options available. As we get started and fill the supply pipeline, we'll launch a pre-order (haven't done one of those in a while) since initial delivery will be a bit over our standard 2 weeks. 


Older Post Newer Post


  • dave on

    Hi Al – The primary thing that offsets do is simply increase off side tension relative to on side tension. They do a tiny bit to stiffen the wheel, but these absolutely don’t need any more lateral stiffness. The 650b rim we’re doing with this supplier is offset, but these are their rim designs, not ours. I can’t say that a blank sheet of paper would have us definitively go in either direction, there are arguments both ways.

  • Al on
    Seems like a great price point. Curiously, why you decided not to go with a 2 mm offset? You’re 24 spoke wheel would be stiffer than a 28,at least laterally. Especially since you’re promoting this as a RCG product?
  • Dave on

    Sterling – Thanks, and that is a PHENOMENAL question, and it will undoubtedly be fully addressed (inasmuch as we can) in a forthcoming post.

    Briefly, you get more hub for the money with the HED build. HEDs with Kings are just a bit more than RCGs with Aivees. Not that Aivees are deficient hubs at all – they might actually be the buried lede in this post. But I think if two sets of hubs were on the table and “pick one,” you and I and everyone else would pick the Kings, right? So there’s that.

    I’d rather hit something sort of “big but relatively incidental” with RCGs rather than HEDs, because the RCGs are going to shrug off a lot of things that would dent and perhaps even terminalize an alloy rim. If I hit a granite curb at full mach, I’d rather replace a HED rim than an RCG, because the HED costs less.

    Speed wise? Is there anything in it? If you held a gun to my head and said “pick the faster one” I’d pick the RCG. Would I have made the right choice? Would we ever find out? I don’t know. HED builds are very stable, but we can (and have) put an RCG on this rack deal we have and jump up and down on the spokes and can’t move it out of true. Alloys eventually move when you do that.

    For cross, RCG hands down. So far as we can tell it’s nearly unburpable.

    That’s about what I can put in a comment.

  • Sterling E on

    These look awesome – bigly.
    Would be curious on how these compare to the HED Belgium + disc builds. Deeper wider lighter and not much more $, but any other performance differences worth noting?

  • Dave on

    Mike – Glad you think so, we think a lot of people will as well.

    Eli – Nothing deeper planned, no. Wider and less circumference-y, yes. Widest part is just about at the outside edge, which makes sense for this depth of rim, and really though these are in absolutely every likelihood just fine in the wind tunnel, asymptotic aerodynamic optimization was not on the podium of consideration in getting to these.



Leave a comment