If you are thinking about trying a tubeless set up for CX, it’s finally become a decent option, provided you take some precautions. In the past, converting a CX bike to tubeless wasn’t a very reliable choice. Rims were narrow and pushed a lot of the load onto the bead and sidewall of the tire. Internal rim shapes didn’t provide a supporting base to help hold the bead in place. Tires were porous and beads would stretch and loosen up over time. It took a ton of experimenting and trial and error and you still never knew if the tires would hold until you pinned on a number and tried them out. It meant you had to spend most of your races wondering if every bump and compression corner would be the one to burp the tire and spill sealant everywhere. A properly glued tubular you knew was going to stay in place and even if it did flat, you could ride it to the pits as it stayed on the rim.
The last few years in the bike industry has made using tubeless on your CX bike much easier. The industry as a whole started making the shift to wider rims across the board. Mtb, CX, road, all have started to embrace a wider rim. They’ve also figured out how to shape the interior of the rim to help hold a bead in place. Most rims now have a shelf next to the bead and a deeper center channel, instead of a constant radius from bead to bead. Also, tires are getting better about being converted over to tubeless and many are coming with tubeless beads.
Of course the popularity of gravel riding and CX bikes making the switch to disc brakes has sped along the development of tubeless. For gravel and backcountry riding, the reliability of tubeless is a very enticing thing. No more pinch flats and some sealant to deal with the occasional thorns or glass. Before you’d have to pack a few more tubs and patch kits to be on the safe side. Now a couple of tubes, and a glueless patch kit and you’re good to go. Disc brakes taking over in CX meant that now you were no longer able to use your various road wheels as CX race or back up wheels. There’s a few of us out there that are starting over from scratch on our wheel collection once we bought our shiny new disc braked CX rig. The allure of not having to shell out for a bunch of new wheels at the same time is pretty alluring. Having a set of wheels that we can use for anything from road riding to gravel adventuring to CX racing with just a quick tire swap is a great idea.
Now there’s a good selection in rims for a person wanting to have a set of wheels that can be set up tubed or tubeless with a wide variety of tires. You can choose from all sorts of CX and gravel tires and even higher pressure road tires. HED, Pacenti, Kinlin, Stan’s, Velocity, etc. all make fine alloy rims that set up nicely for tubeless disc CX wheels. They usually are semi-aero (about 30mm deep), about the same width (23-25mm), and range in weight from 435-500 gms. You can build a relatively light, affordable set of wheels with these options. Being they are alloy, you’ll want to use a higher spoke count of at least 28 and depending on your size and riding style, a 32 spoked wheel might be a better option. A slightly heavier gauge double butted spoke wouldn’t be a bad idea either. Pairing a low spoke count, more flexible alloy rim with lightweight thin spokes doesn’t make for a durable or precise riding wheel. If weight is a concern,you can build up a lighter weight mtb tubeless rim into a CX wheel like the Crest or Iron Cross from Stan’s, but you then lose the ability to safely run more than 45-50 psi. Those rims are designed around a low pressure mtb tire application and are less than optimal for someone looking for a dedicated CX/gravel/road disc tubeless wheel.
If you are looking to build up a lighter set of disc wheels that can be used with tubes or tubeless, at higher pressures with a road tire, low pressures with a CX tire, or somewhere in between with a gravel tire, then carbon is a good option. The weight savings when comparing a alloy clincher to a carbon clincher isn’t very much, if at all in some cases. What carbon offers is a much stiffer rim, which allows you to use lighter gauge spokes and less of them than you would in a comparative alloy rimmed wheel. You can choose a slightly deeper profile to gain a little bit of aerodynamic efficiency back. That deeper rim will use shorter spokes too, and shorter is lighter and stiffer, meaning the wheel will track better and be more durable.
The only real downside to carbon rims is cost and it’s twofold. The first time is when you have to buy the wheels. Carbon is more expensive than alloy. Especially for a decent rim. The second time you’ll feel the sting is should you do something catastrophic to the rim while riding and you have to replace it. The pain in the wallet is higher when you have to replace a carbon hoop vs. an alloy one. Carbon inn’t more fragile or delicate than most alloy rims, in fact a blow that would destroy a carbon hoop would probably do some pretty bad things to an alloy rim too.
I’ve managed to source a fairly affordable source of Taiwanese made carbon rims if you are interested in having a set of wheels made. These are available in a few depths (25mm, 35mm, 45mm, and even 55mm) to tailor them to your exact needs. They can be run tubed or tubeless, both road and CX, with virtually no pressure restrictions (Up to 120psi, but no one should run that high of pressures outside of a velodrome anyway). You can choose a variety of hubs and still have a great riding wheel at an affordable price point. I like to build with hubs from Chris King, DT Swiss, White Industries, I9, Shimano, and my own house brand hubs as well. As always, each wheel set is custom made for you, by me. Nothing stock or off the shelf. Call or email me if you are interested in a set of either carbon or alloy tubeless ready CX wheels.