Tubeless continues to be the source of a lot of questions, so I thought a brief primer would be in order.
Tubeless is a subset of clincher, by which I mean that all tubeless tires are clincher tires, and all tubeless rims are clincher rims. A tubeless tire can be used on any clincher rim (subject to a few specific tire/rim fit cases), and a regular non-tubeless clincher tire can be used on any tubeless rim.
A tubeless (often called tubeless ready) rim has a few specific design features, the critical one of which is the "trough and shelf" design to the tire bed, shown in the red line in the picture below. The trough allows the tire to be installed more easily. When you inflate the tire, the beads get pushed out onto the shelf. The shelf then holds the beads securely up and out, minimizing the chances of air escaping between the bead and rim (the dreaded "burp"). Instead of normal Velox-type rim tape, different non-porous rim tapes are used as well. All wheels we ship have this tubeless tape installed, as we find it also works better in tubed applications than traditional rim strips.
Installing a tire (whether tubeless or not) onto a tubeless rim is a little bit more exacting, but is easy with the correct technique. Watch this video to see how we do it.
The way we think of it, tubeless goes into three categories: road tubeless, cross/gravel tubeless, and mountain bike tubeless. A brief explanation of each follows.
Road Tubeless: Subject to manufacturer interdictions, any clincher rim can be used for road tubeless. You have to prep the rim with an appropriate tape to cover the spoke holes, and you need tubeless valves, which are the same basic valves as you see on inner tubes, only they're not attached to a tube. The valves need to be secured to the rim using a nut. The biggest thing with road tubeless is that you absolutely MUST use tubeless specific tires. The beads on tubeless road tires are reinforced. The beads on regular clinchers are not capable of withstanding the pressure of tubeless use and may blow off the rim. Apart from that one caveat, road tubeless is very easy. Sealant is used to seal the tire/rim interface, and very capably seals small punctures. We're fans of road tubeless.
Cross/Gravel Tubeless: Cross tubeless is the most exacting tubeless setup. Because the tires are low volume and run at low pressure, the tire/rim interface is critical. With the right combo, cross tubeless can be more secure than tubulars and glue (which is the first time I've said that out loud in public, but it's true). Here is the whole nine yards on what we tested for setups last year. You do not necessarily need a tubeless ready tire for cross tubeless, however we have found that they work much better in general. Based on what we've seen, using non-tubeless rims for cross tubeless is a waste of time - without the shelf design, the tire will burp and you'll be frustrated. Gravel generall uses higher volume tires with more pressure, and less jumping onto the bike and fewer off camber-ific turns, so its much less demanding than cross, but generally similar. We are big advocates of cross/gravel tubeless.
Mountain Bike Tubeless: This one's pretty easy. I don't even know if you can get a non-tubeless mountain bike rim anymore, and the enormous volume of current mountain bike tires means they've got enough pressure to stay on securely come hell or high water. The lower tire pressure means less bead pressure, so you don't need tubeless specific tires, either. You might need a fair bit of sealant to get some tires to be airtight, but once that's done it's pretty much set it and forget it. It's no wonder that mountain bikes were the first heavy adopters of tubeless - it's so easy and it works so much better than tubes. Mike doesn't really mountain bike anymore and I don't as much as I used to, but I wouldn't go mountain biking with a tubed tire setup.
In all cases, any flat that the sealant won't fix (and in our experience these are RARE), you just take out the valve and install a tube just like you would a regular flat. Easy peasy.
Who knows what the future holds for tubeless, but if you're interested in giving it a try it can work really well.