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Onyx hubs are known for their instant engagement, thanks to a Sprag clutch system that expands metal pins between two steel rings to engage. Because the pins are basically dragging on the rings’ surfaces, they rock into a locked position within a fraction of a degree of rotation, which is virtually imperceptible. The downside is they’re heavy – that’s a lot of steel, and they need two rows of the clutch to handle the torque, especially for mountain biking.

prototype onyx cyclocross and mountain bike hubs woth lighter shell and modified half clutch system

Now, they’re working on a new design that has a lighter Sprag clutch system inside, using one full clutch with a half clutch behind it, rather than the usual full dual clutch. Shown above, the full dual clutch is on the right in the see-thru hub shell. A version of the 1.5 clutch is on the left in the cutaway, shown in a road version that’s slightly different than what will end up in the new hubs… which get both the Centerlock and 6-bolt brake mount options.

prototype onyx cyclocross and mountain bike hubs woth lighter shell and modified half clutch system

They can’t use just one clutch because it won’t have a high enough torque value. As mentioned, the clutch has to be backed by a steel sleeve on both sides, so reducing the size of it reduced weight quite a bit. The target weight for the new design on a 142×12 is 320g. Their current hub is 414g, so it’s a big drop.

They’re working on a 148×12 (Boost) model, too. No ETA yet, but it’ll also get a new end cap system that makes it easier to swap. Why not Boost to start? Because the original idea was to use it for cyclocross, and they literally just started working on this prototype a few weeks before coming to Interbike.

alloy freehub body with steel inserts for onyx hubs

If you just can’t wait for those new designs, which are at least 6-9 months out, you can swap in their new alloy freehub body, which comes in 70g lighter. It’s a pinned design that slides steel u-shaped pins into the alloy body, to prevent the cassette from biting into the softer aluminum. As they wear, you can slide them out and flip them over, doubling their life, or just replace them.

All of their hubs come stock with ceramic hybrid bearings (ceramic ball, steel race), and now you can even get them with a Campagnolo freehub body.

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  1. neologisticzand on

    Loved everything about these rear hub besides the weight when I had it. Glad to see they are further addressing the high weight.

    • Seraph on

      Still pretty high weight though. My 144 POE Project 321 hub weighs about 280g and has plenty of engagement points. They even offer it in a 216 POE option for those who want less float.

        • Robin on

          A more accurate statement would be that hub weight has minimal impact on rotational mass since a hub’s radius is very small compared to the wheel radius. A very small radius is not, however, a radius of zero (insert your preferred units of length).

          With that said, the influence of rotating mass on bicycle/rider systems is overestimated and overblown.

          • neologisticzand on

            Vincent, that was exactly the issue I faced. The hub was on a full-suspension mtb, which also had an 11 speed X1 cassette and rear mech. Which ends up being quite a lot of weight in the end.

            And to the people asking about maintainance, I never noticed any degradation of performance and I never serviced the rear hub despite it seeing a lot of bad weather on my mtb.

        • ol shel on

          The negative affect of rotational weight is way overstated, primarily a misconception that the high-end wheel makers are very happy exists. Sure, there’s a difference, but few will notice. The amount of energy to accelerate a light wheel vs a ‘very light’ one is minimal.

          Additionally, for off road use, don’t discount the benefits of a little bit of additional mass away from the hub. Super light wheels are skittish, and more easily knocked off line. Most people will be happier with ‘normal’ wheel weights, even if they refuse to believe it.

  2. Kevin on

    What neologisticzand said! I have one of the original, heavier ones and it is such an awesome hub. I grew up coveting the Angry Bees, but now that I’ve adjusted, I love the silence of the Onyx even better. Just the sound of me huffing along and my tires biting the trail!

    • joel w pontbriand on

      hey, amen-i’ve got a pair of vintage velomax circuits that have the smoothest hubs i’ve ever ridden and the best part is they are totally silent!!! i loathe the day that i’ll wear them out!!

  3. Ish on

    Onyx hubs are awesome. Yes, the instant engagement is great for ratcheting rock gardens but the silent and almost drag free coasting is the ticket for me. 15-25% of a road/CX/mtb race is spent coasting. Free speed is free speed even if it is marginal, plus it is nice to hear your tires in the dirt! The weight penalty(and soon less of one) is worth it.

    • David on

      I have my pair of Onyx on a daily commuter that goes through MN winters. Literally sunken in snow and salt every day and after a few thousand miles they are, as if, brand new.

  4. Mark on

    I love their hubs too- both the silent coasting- and the instant engagement. And their customer service is also fast and responsive.

    I guess most of this article applies to mtb and thru axle hubs. They’ve had single sprag in their 130mm road hubs, and even the dual sprag road hubs were full and half width sprags. And available in Campy. And yes, they were certainly much lighter than the mtb hubs.

    Maintenance: there are videos on their website. Teardown is pretty straightforward, only requiring Allen wrenches and a bearing puller if you’re replacing bearings.

    I believe (but don’t quote me on this) that you can send your wheels back to them and they’ll clean and regrease gratis, but you’ll have to pay for shipping, so it’s probably cheaper to diy. I forget what the service intervals are. Obviously, it depends on your riding conditions and frequency.

    Customer service: they’ll sell you individual components, so if you want to change hub shells- say from a six bolt to centerlock- they can sell you just that, though I forget, they may want you to send it back to them so they can do the labor and make sure everything is working well.

  5. Ripnshread on

    This clutch style looks sweet. That’s a pretty light for what it is. It can only get lighter too. Looks like they overbuilt the current version and are now paring back. Good safe reliable progression. Now lets see them introduce some more exotic materials…bet they could drop and ounce or two. But I’d get ’em now if I was looking.

  6. J-dog on

    Ride one of these hubs, you will not forget the experience. The absolutely silent coasting is pretty interesting, especially when mtbing.

  7. Colin on

    Riding Onyx hubs in, on the road, in a group, takes a little bit getting used to. I found myself having to drag the brakes just a hair because I wasn’t used to how freely they spin. Also now when I ride Shimano hubs, I can’t stand the insane racket from the back end. You also tend to accidentally sneak up on people.

  8. Matt on

    Got my first ride on my new Onyx hubs this weekend and they were everything I hoped for and more. I just built up a new bike with these hubs and my first ride I got 16 PR’s and a KOM. I can’t attribute it just to the hubs but I could definitely feel myself going faster on certain sections of trail. I also rode with a group for the start of the ride and found myself having to brake a lot more often on coasting sections because I was catching the guys ahead of me.

  9. turok on

    Honest question here, what sort of engagement setup to True Precision Stealth hubs use? They’ve been around way longer than Onyx and claim instant engagement and silent coasting but they don’t actually say they use a sprag clutch. Is it something different? Like a roller clutch perhaps? Anyone know?

    • SV on

      I found this on the True Precision website: “The engagement mechanism in our hub is a roller clutch. The roller clutch is common in many industrial applications. We have adapted it for use in a bicycle hub. The clutch looks like a needle roller bearing at first glance, but inside the outer race behind the rollers is a series of ramps and springs. When the clutch engages the rollers ride up these small ramps and lock onto the drive body (our name for the part that the cassette/cog is attached to). This allows the transmission of power from the pedals to the wheel. When coasting, the tiny springs behind each roller push the rollers down the ramps and allow the drive body to rotate inside the clutch. Since the clutch is composed of only rollers and not any pawls or face ratchets with teeth, it is totally silent when coasting.”


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