If you could design the perfect drive mechanism, what would it be? High engagement? Low drag? Quiet? Those were the answers Project 321 were looking for when they set out to design a new drive system. It seems that riders are still split between loud and quiet hubs, so they thought – why not do both? More importantly, while the new drive system allows the rider to choose the volume of their pawls, it also creates a system that claims to have far less drag while keeping the high degree of engagement, all with fewer moving parts…

The secret to the P321 Drive system lies in their magnetic pawls. But how do they work? Project 321 says the key to the design is that unlike a traditional pawl spring, the magnetic pawls offer the greatest pawl force against the drive ring when the pawl is fully engaged as the magnet pulls the pawl into the drive ring. As the pawl gets father from the drive ring teeth during freewheeling, the force and therefor drag is reduced. Project 321 says this is the exact opposite of a traditional mechanical push spring and that when the pawls are disengaged for freewheeling, the drag is at its highest since the spring is compressed and being pushed back into the drive ring.

The P321 Drive System uses 6 magnetic pawls in a 6×2 or 6×3 driver configuration where only two or three pawls engage at one time. The 6×2 drive is the standard option which provides 216 points of engagement at 1.66°. The 6×3 driver is really only necessary for tandems, e-bikes, or riders over 275lbs and drops the engagement to 144 points or 2.5°. Either option includes a 3 year warranty on the driver.

As for the sound options, there are two different pawl sets, one for loud and one for quiet. You can get a sense of the difference in the video above, but it’s a substantial change. The two sets of pawls have a different shape, mass, and magnet, which changes the sound of the hub. It also changes the drag with the quiet pawls offering a claimed 68% less drag and the loud pawls offering 51% less drag than their previous system (Industry Nine).


Then there is the oil volume of the hub which isn’t something we typically think about. Project 321 actually increased the oil volume by adding a bunch of machined holes under the driver in the hub shell. They say this will not only help dampen the sound further, but also increases the time between service intervals. The only part that moves on the drive system are the 6 pawls and the driver body itself.

Even though Project 321 now offers the P321 Drive System on all of their rear hubs, the system is also backwards compatible with current G2 hub shells. Project 321 claims that they have had zero hub shell failures of the current G2 design, so they extended the warranty to 10 years for the axle and hub shell, as well as made the new driver backwards compatible. Available for XD or Shimano, SS, Boost, and nearly every axle configuration, a hubset will run about $600 with pricing on the driver itself TBA.




      • myke2241 on

        There is a white paper for that. Onyx are better. Why even argue 321 has a engagement ring. So it’s already limited out of the gate!

        • turok on

          onyx hubs might be quiet but they are incredibly heavy, expensive, and the torque you can generate with most 1x setups can cause them to twist. They do not feel solid like any hub that uses pawls. Try one with a belt drive or a 1x in your lower gears and you’ll know what I’m talking about.

            • turok on

              I’m not saying its not possible, or even that it would always be noticeable. It depends how much torque you apply to the system. I ran a 1x and in the 30×42 it felt like I was threading a freewheel on all the way up every hill. A SS isn’t going to allow you to apply that kind of torque, unless you have the lowest SS gear I’ve ever heard of.

              The only reason I mentioned belt drive is because a chain has a bit of stretch where a belt doesn’t, you can feel more subtle things happening with a belt drive than with a chain.

              If you love your onyx(and a lot of people do), then cool. I’m sticking with pawls, even though I liked the silence.

              • Dylan on

                You honestly believe you can feel elastic deformation in a chain? Even if you could generate enough force to stretch a chain (nope), you would be twisting the cranks, winding up the spokes, deforming the tires, bending the laterally stiff yet vertically compliant rear triangle by orders of magnitude more. Sorry, but feeling chain stretch through your legs just isn’t a real thing.

                • JasonK on

                  Dylan, normally I would share your skepticism. But, reading carefully, Turok is NOT saying he can feel elastic deformation in a chain. He’s saying he can feel windup in the Onyx hub. Onyx hubs use a sprag clutch, and sprag clutches do wind up slightly in a way that pawl-based freehubs don’t. He’s not talking about elastic deformation, but rather an effect unique to sprag and roller clutches.

                  I have an Alfine 11-speed bike. Those hubs use four(!) roller clutches, and I can definitely feel windup in that hub. Depending on which gear I’m in, the windup of all four roller clutches can be stacked, so it’s readily perceptible. I don’t doubt that in a 30×42 on an Onyx hub, you could feel the clutch windup. You could even see it with the bike stationary and the rear brake locked…you’d see the 42t cog rotate slightly relative to the stationary spokes.

                • turok on

                  Forget everything I said about belt drives and singles speeds. Just try to climb a hill in a low gear with an onyx hub. See what you think.

  1. D-Con on

    Was really impressed by these at NAHBS. I’m over the straight pipes school of freehub design – especially with companies like Onyx and P321 proving that noise is not required for fast engagement. Just like loud motorcycles they’re more about attracting attention rather than safety-and no one outside of the club thinks that they’re cool.

    As one editor put it: “Hear my MONEY!”

  2. Keith on

    The best products on the market….P321 hands down! I own 5 sets of their hubs and I have NEVER experienced anything but bliss. As a former aerospace machinist I really appreciate the quality Jake and the team at P321 deliver!!! Keep up the great work guys! Thank you for your relentless pursuit of perfection in product and customer service;-)

    • mbC on

      Yeah. I’ll buy that when I see someone on straight pipes wearing visible colors and the most basic safety gear (skull facemasks and leather vests don’t count). The “Straight Pipes Save Lives” stance would be a lot more believable if people were at least taking at least some responsibility for their own road safety.

      I’m on the side of the quiet hubs. Like loud exhausts overly loud hubs can be a way to get attention at the expense of everyone else’s road/trail experience. Be nice, use a bell, smile, and say hello.

    • P321 on

      Not exactly. However the Kappius hub was one of the inspirations for this design. And while they didn’t invent using a magnet in a hub they did do it well. I have a ton of respect for the Kappius family and Kappius line of components. But our magnets are positioned differently which is what allows the amazingly low drag on the quiet pawls. You can read more about it here if you want. http://www.project321.com/updates/new-drive-system.html

  3. Andy S on

    Yes Onyx are heavier, getting the aluminum driver does help bring the weight down quite a bit though. To me the super low drag, smoothness, craftsmanship and looks outweigh the weight penalty. I looked to see what P321 drivers are made of but I don’t see it listed, anyone know?

    As far as pricing goes, Onyx and P321 hubsets are similarly priced. Secondly Onyx come with ceramic bearing as standard (an upgrade for P321).

    Not hating on P321, I like what they have done here and would consider them for future builds.

  4. chase on

    On balance Chris King (angry bees and all) still win the purchase decision. As person who for the most part generates tandem torque I have destroyed pretty much any pawl system. CK have withstood 20 years of abuse with almost no maintenance. Amazing. However their delay in getting Centerlock out is driving me nuts!

    • Mike D on

      You must only ride in the sun, ha.

      Here in the PNW if you don’t do a full service on the rear hub 1-2 times a year you’ll be replacing the ring drive almost guaranteed. I’ve seen them work great elsewhere, but the weather here is hard on them (ironically, CK is headquartered here). We have to explain it to customers who had assumed they had purchased the ‘Holy Grail’ of hubs all the time–you may have bought the Ferrari of hubs, but the parts and maintenance aren’t cheap! Also, I’ve never had owners of other hubs tell me that they have had to pee on their hub in sub-freezing temps to free them back up. I know 3 people (only one is a customer of ours) who have shared that same story.

      And none of that is to take away from your experience–I’m stoked that they have been great for you! I’m just sharing another side to the CK story, being that they *are* nice hubs, but not without some drawbacks (cost, maintenance).

      • Tim on

        They are light, do have fast engagement (though the days when they were the hub that offered the most rapid engagement are now long gone, and they are sitting on their laurels), and look sharp. But… I have seen around fifteen bikes equipped with their rear hubs, and every one of them had a small amount of play in the bearings. This includes hubs on shop mechanics’ bikes (mine among them). I couldn’t get mine to work without play, and rode it that way for years.

        • Bruce Big M on

          Alas, finally a bit of truth about CK rear hubs! While pretty and noisy, they tend to have bearing play that can’t be adjusted out. Weak sauce.

      • Hugo on

        When I was living in Portland over a decade ago, I finally got fed up with destroying hub drive systems. I went in to the shop intent on buying a Chris King. The owner, who I trusted, pointed me at a Hadley. He knew I wasn’t big on maintenance and that I was a bruiser. I’m still on that hub and have only rebuilt it once. The Hadley is no where near as good looking as the King, but it could handle at least as much torque , be serviced with off the shelf lubes, was just as loud, and required a fraction of the maintenance. I’m about to start my third relaxing of that hub and couldn’t be happier. Though these P321 are now on the table for my next set of wheels.

  5. dave on

    I also have been asking for centerlock option, the more we ask the sooner it will come!! Also would love to see a cool electric green color. I have Onyx and the New Project 321 216/quiet version hubs, also Have Hadley, Dt Swiss 240 and 350 hubs. The no noise thing and 0 drag is why the went with Onyx hubs on downhill bike. Now that Project 321 has 216 points of engagement are also most as quiet as Onyx but weigh so much lighter than Onyx.

    Jake with Project 321 has designed and built a hub so nice and light, quiet, low drag. Built with pasion in USA, Project 321 are the hubs I tell people about now!! I love the new 216/Quiet hubs!

  6. dave on

    Tim, Boost hubs have been out for a while now, I have 2 sets of Project 321 hubs both are boost front and rear. When is that new web site coming!! Sending my second set out now for upgrade to 216/quiet. I also love the fact I no longer need to ever deal with the old system and those supper small paul springs that I would alway’s lose!!

  7. Bret on

    I’ve been using P321 Lefty adapters for a while now and love Jake’s craftsmanship. I also would like to see Centerlock. Especially with boost now, I would also really like to see angled flanges like the new SRAM hubs. It’s so nice building wheels without having to bend the hell out of the spokes!


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