Our disc brake carbon rim lineup consists of four different rims leading to an infinite number of possible build combinations, and though there is significant overlap in their use cases, each has specific purposes to which we think it's better suited than the others. Well, there's really not any overlap between the GX24 and any of the others - that's more of a complementary situation.
The GX24 is a 650b/27/5" rim that's ideal for gravel and cross country/all mountain mountain biking. The 24mm inner width (also the depth) sets up perfectly with tires from 45mm to 2.3" wide. The 385g rim weight is light, generally saving you around 50g per rim compared to alloy alternatives, but at that weight the big thing is its strength. There are lighter rims out there, but we've never seen a lighter rim of similar dimensions as stiff and strong as the G24. As with all of the other rims in this group, it's easy to set up tubeless. A small offset equalizes on and off side spoke tensions.
The GOAT28 is good for anything, or Great On All Terrains as the name says. Very slightly wider than the RCG36 and Cafe Racer 46 at 22.5mm internal and 29.5 external, with a 28mm depth and again a small offset to help equalize on and off side spoke tensions. Very stable, quite stiff (there's almost no spoke tension drop when you install a tire) and light at 375g per rim. It's pretty easy to do a set of these under 1350g, if that's your thing, and they're still good for very hard use at that built weight.
The RCG36 is also versatile, an outstanding choice. Like the Cafe Racer, it's 21.5mm internal and 28.5 external width, and center drilled with no offset. We feel that the offset is better suited to lower profile rims which naturally have worse bracing angles than deeper rims. 410g rim weight puts it into climbing wheel territory (under 1400g is easy to do).
The Cafe Racer 46 is a sexy beast. It's been scientifically proven that road bikes look the most badass with this depth of rim. At 435g/rim, you're still getting climbing wheel built weights despite the depth, and the cross wind manners are impeccable.
So here's a quick run through of which uses you might possibly have, and our quick take on which rim would best suit each:
650b bike of any type: GX24
Dedicated cross racing bike: GOAT28 - it's light and tough and holds a tubeless tire on like crazy. Get 2 sets for the price of a single set of equal (if even that) quality from most brands and you can easily cover all your race conditions and have pit wheels that you'll actually want to use. RCG36 is also a fantastic dedicated CX rim.
Adventure bike: GOAT28 - you're going to use wide tires and you might as well go light and strong along with that width.
Cross bike that gets used as an everything bike: RCG36 or GOAT28. The RCG36 might be better suited to group rides and racier paved stuff while giving almost nothing away when used for cross or gravel rides. The GOAT28 is absolutely perfect for cross and gravel, while giving away very little on the group rides and racier paved stuff.
Gravel race bike: GOAT28, RCG36, or heck even Cafe Racer (though in that order). I'd choose the lightest, widest rim for myself here, so that would be GOAT28. If you had a set of RCG36s, though, you'd be darn near perfect with those. And there are plenty of people looking for the maximum aero even on gravel racing, so the Cafe Racers are far from wrong.
Dedicated climbing bike: Always kind of surprised by how many people have these, but GOAT28. Set up with latex tubes or tubeless with a pair of 25mm road tires, you get crazy light weight to help you go up fast (even if the help is just knowing that your setup is light), unbelievable handling to get you down fast, and zero effects from crosswinds to sap energy or take you off your line.
Gran fondo/general nice long rides bike: RCG36. Light, great handling and manners, strong and tough. Higher volume road tires from 25 through 38 and bigger set up sublimely on RCGs, while they're still perfectly happy with 23s if that's your bag or that's what fits in your bike (because a lot of "23s" are going to be almost 28 on them).
Fast to faster road riding and racing: Cafe Racer. Not only do they look cool, they make a very awesome whooshing noise at pace, and they do crit type cornering as well as anything I've ever seen or used. Very likely the fastest of all the wheels and the easy equal of anything similarly deep. Very well mannered in cross winds. Dead sexy.
As always, how these get put together, and the components they're built with, are as important as anything else. Our goal standard for every build is absolute perfection (which you very rarely get, but man do we get close a lot), and we offer a range of hubs and spokes that cover your preferences and budget options.
Because it bears mentioning every time, we'll again mention that there's nothing magical about carbon and we quite haven't abandoned alloy. But with rims now not being wear items thanks to disc brakes, and the better chemistry and constructibility that disc brakes afford, the toughness and weight advantages of carbon rims do become compelling when combined with the "not really that big" price premium that these builds ask.