Nobl came on the scene at a time when carbon wheels were still thin on the ground and universally bore price tags that put them out of the reach of just about anyone who didn’t happen to be a plastic surgeon or third-world dictator. A lot has changed since then, with plenty of carbon hoops selling for about half of the damage of those first few carbon wheelsets. Nobl now offers several different carbon wheelsets, in both 27.5 and 29-inch trims, and in a range of different rim widths. Nobl’s TR33 wheels can be had with a variety of hubs, including the Hope Pro 4, Industry 9 Torch or Nobl’s own sprag-clutch model, built for them by Onyx Racing Products in Blomkest, Minnesota.
Available in 27.5” and 29” sizes, the TR33 wheelset retails for between $1,295 USD (with Hope Pro 4 hubs) and $1,550 (as tested here, with Nobl's Onyx-built hubs). Both Boost and non-Boost options are available. Our 27.5-inch wheelset weighed in at 1,810 grams, including rim strips and valves.
Nobl (Onyx) Hubs Nobl makes some big claims about these hubs. Namely, that they offer “the best overall performance of any bicycle hub.” Bold claim. Let’s unpack that. The heart of the Onyx-built hub is its sprag clutch—a design that is said to offer infinite engagement yet zero drag and absolutely no noise.
How could that possibly work?
Most hubs that offer quick engagement do so by ratcheting a set of pawls over a whole lot of fine teeth or points in the drive ring. As you can imagine, this generally creates more friction (and a mini-chainsaw howl, which some people dig). The upside, however, is less lag between the moment when you put power into the cranks and the moment the rear hub engages. You can argue that quick-engaging hubs represent more of a benefit for trials riders and BMX racers than trail riders, but all things considered, a quick-engaging hub does feel awesome and it’s one of those traits in a rear wheel that some people live and die for. To each their own.
This clear plastic model shows the two sprag clutches that are found inside of the Onyx hub shell. All those separate metal pieces are referred to as sprags, and they allow the freehub to rotate in one direction but wedge tightly against its barrel when torque is applied in the opposite direction.
The barrel that extends out from the freehub body is what the sprags grab ahold of.
A sprag clutch has the same aim, but goes about achieving it differently. In the center of the Nobl hub shell are two rows of spring-loaded, metal wedges—29 in each row. These are the “sprags”. The shape and orientation of the sprags allow the drive barrel, which runs from the freehub into the center of the hub shell, to roll smoothly—with almost no drag at all—in one direction. The moment the barrel moves in the opposite direction (when you begin a pedal stroke) all those sprags bind against the drive barrel. Instant engagement. Mike Levy described a sprag clutch aptly as a device that acts like a “one-way bearing” and that’s an excellent description.
If all that seems like so much gibberish, check out the short YouTube clip (at right). The first 10 seconds are sort of goofy, but it quickly gets to the point. The red circle in the video would be the drive barrel and the blue ring is the inside of the hub shell.
Nobl designs their own rims--everything from the exact shape and dimensions to the layup schedule.
The hookless rims come with tape and valve stems pre-installed. Tubeless tire installation and removal are absolutely painless.
The TR33 features an inner rim width of 27 millimeters. Nobl offers wider rims (their TR38, for instance, has an internal width of 31 millimeters), but since most 2.35 and 2.4-inch tires on the market were designed back when 21 millimeters was considered genuinely cavernous, I opted for a width that gives good sidewall support, yet doe so without transforming the tire’s tread profile into something that looks like a rubber mohawk.
Though Nobl relies on a Far East manufacturer to get the deed done, they are adamant that these are not “off the shelf” models. Nobl designs their own rims—dictating every aspect of the shape and carbon layup and they own their own molds. The rims are tubeless-ready—the wheel comes with rim tape and tubeless valves pre-installed. Each 385-gram rim features a three-millimeter hookless bead, an asymmetrical profile and a tire-bead seat bump (a slight ridge that runs between the sidewall and the rim's center channel) that is supposed to reduce the risk of you burping a tire or, worst case scenario, peeling it completely off the rim.
I wound up running the TR33’s for the better part of a season and they are still rolling completely free of wobbles and hops. The wheels hold a true. Should you need to get out the spoke wrench (an inevitability, of course) there’s nothing exotic (and, consequently, exasperating) to contend with here. Thirty-two, three-crossed, J-bend spokes on each wheel are easily trued and available at just about any bike shop on the planet.
The hubs, which feature angular-contact, hybrid-ceramic bearings are still rolling buttery smooth despite loads of mud and rain. And, yes, they are quiet. Dead quiet. With a clutch-equipped rear derailleur on your bike, the only noise you hear is the sound of your tires gripping soil. It’s pretty awesome, actually.
As for the engagement—yes, it’s instant. There is no hesitation at all. But—and this is worth noting—the sprag clutch has a very different feel from, well, just about every hub you’ve probably ridden. I never thought of any hub as feeling particularly “crisp” before, but the sprag clutch mechanism here has a softer, muted feel to it when you stomp the pedals. So, yes, the hub engages blindingly fast, but the feel at your pedals may not be what you’re expecting. I grew used to it over time, but every time I jumped on another wheelset, the difference was immediately noticeable.
Why the difference in feel? Looking for an explanation, I turned to an engineer who, frankly, knows more about clutches than I’ll ever know (and who builds airplanes in his living room). In other words, here’s what RC had to say.
“The issue is ‘hoop tension.’ A ratchet system engages teeth at an obtuse angle, which puts very little vertical force on the outer diameter of the hub shell. The sprag clutch, however, is made up of a number of vertical levers that capture the rolling surface below with a rocking motion that puts a huge amount of force into the hub shell, and that causes it to expand. That slight expansion allows the sprags to rock farther than they normally should, which can be seen and felt as the cassette acts as if it is attached to a spring and not a solid connection with the hub. Both sprag and roller clutches (which have similar engagement properties) must be encased by a rigid steel structure to prevent that from occurring - which is simply not possible if you want to build a lightweight hub shell.”
So, there’s that. The soft feel at the pedals may be off putting to some riders--particularly heavier or more powerful peddlers. If that describes you, I'd recommend going with the Industry 9 hub option, which will give you that nice crisp feel and very quick engagement (albeit, with a fair bit of ratchet noise when coasting). Moving on. now...
Getting tubeless-ready tires to properly seat on the rims proved remarkably easy—a floor pump got the job done every time. You do have to do a bit of squeezing to dislodge the tire beads from their perch in that specially-molded bead bump, but I was still able to take a variety of tires off the wheels without ever resorting to using a tire lever. In short, running tubeless is completely painless with the TR33.
A lot of people assume that a carbon wheel is going to be incredibly light. You can get the TR33’s down to a very svelte 1,471 grams if you opt to run the Industry9 Torch hubs and Nobl’s Ultralight spoke build up (retail price on that particular wheelset is $1,495). Likewise, a similar build up with Hope hubs will tip the scales at 1,525 grams. Our test hoops, however, weigh in at more than 1,800 grams, despite the respectably light, 385-gram rims.
Much of the weight gain comes courtesy of the Nobl hub. The sprag clutch mechanism is undeniably burly (there’s a reason, after all, that you find the design employed in car and tractor transmissions), but it also adds weight to the wheel package. The 142x12 rear hub with a steel Shimano freehub weighs 491 grams; for reference sake, that’s 260 grams (.57 pounds) more than a six-bolt, DT Swiss 240 S rear hub. Nobl also offers their sprag-clutch hub with an alloy (rather than steel) driver, which cuts weight by as much as 71 grams, but but you get the idea: the Nobl rear hub is hefty.
If you want to go light, go with the I9 or Hope hubs. In truth, the weight didn’t bother me out on the trail, mainly, I suppose, because the extra weight is at the center of the wheel, rather than at the perimeter of the wheel. Moreover, I’m more interested in ride quality and durability and this version of the TR33 fit the bill with an absolutely bombproof feel that didn’t prove overly harsh. Just how confident is Nobl in the strength of these wheels? They have a rider weight limit of 130 kilograms (286 pounds), which is kind of like having no rider weight limit at all.
The TR33s have a lot going for them, including bombproof construction, no proprietary bits that will prove a nightmare to service, completely silent operation and very, very fast engagement. Nobl has built a hassle-free set of hoops that will take a beating. However, if you are primarily considering a carbon wheelset because you want to shed serious weight from your rig, you'll want to go with either the I9 or Hope hub options. The Nobl sprag clutch has its benefits, but they come with an undeniable weight penalty. - Vernon Felton