Onyx Hubs Review: Long-term Trail Tested

In our long-term review of Onyx Hubs, Skyler illustrates a few key points to consider when looking at a rear hub for bikepacking and technical mountain biking. Plus, why Onyx’s silent, soft catch “instant engagement” has made him a life-long customer…

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For me, the interest in high-engagement rear hubs all started with a few too many pedal strikes. There’s no doubt in my mind that the trend toward longer, lower and slacker bike geometry has made mountain bikes more capable and fun, but the main penalty for these new-school, lower bottom bracket heights is increased pedal to rock action. It’s a major annoyance that is especially relatable to the bikepacking world. After all, it’s pretty easy to avoid pedal striking on an unloaded bike, on maintained mountain bike trails. Take a loaded rig onto backcountry trails that were likely blazed on foot or horseback, however, and pedal striking can, in my experience, become a major hindrance to forward progress.

  • Onyx Hubs Review, Long-term, mountain biking
  • Onyx Hubs Review, Long-term, mountain biking

Onyx Hubs Review, Long-term, mountain biking

Of course, bottom bracket height is not the only factor that affects pedal striking. Crank length, pedal thickness and shape, and one’s ability to time pedaling through pedal-biting obstacles all have an impact on one’s ability to pedal through chunder. And that latter point – the ability to time pedaling and ratchet through techy bits of trail – is massively influenced by hub engagement.

Onyx hubs’ claim to fame is really in their freehub engagement. It’s instant. Or, it’s imperceptibly close to instant – more on that later.

How Freehubs Work

Probably 99.99% of bicycle freehubs depend on some sort of pawl-ratchet system. if you don’t already know, here’s a video of how that works.

On pawl-based hubs, the number of teeth on the driver determines how quickly the hub will engage when you start pedaling forward. Bike hubs will use at least two pawls – usually three or more – because hubs are small and pedaling torque at the hub is pretty darned high. To have quicker hub engagement in a pawl hub, you need more teeth on the driver, or pawls working out of sync with each other. The quicker the engagement of a pawl freehub, the tinier the driver teeth and pawls get, and these hub pieces get much harder to machine, requiring extremely tight tolerances. The end result is that there’s somewhat of a limit on how precise a pawl-based hub can be made, with them commonly offered with 6-10° engagement and premium choices down to about 3°.

Onyx hubs don’t use pawls or toothed ratchets of any form. For the job of freewheeling they depend on a sprag clutch. Here’s a 1980s animation of how it works:

In short, a row of camming element run between two smooth steel races. They slide freely in one direction and cam in the other, wedging in between the two races with such force that the races cannot move relative to each other. As soon as you start pedaling forward, the sprags engage, no matter their position on the races, which effectively offers an infinite number of engagement points. The downside to a sprag clutch is that the inner and outer steel races need to be very strong, and therefore Onyx rear hubs are about 100-200g heavier than non-sprag competitors.

Onyx Hubs Review, Long-term, mountain biking

  • Onyx Hubs Review, Long-term, mountain biking
  • Onyx Hubs Review, Long-term, mountain biking

It should follow that Onyx’s rear hub engagement is instant, but there is a tiny, barely noticeable amount of rotation required to load the sprags in the clutch. It is probably less than one degree of rotation before the sprags are fully loaded, but because of the nature of camming devices, the “catch” of the freehub feels soft, as the sprags are gradually loaded. There’s no hard on/off stop that one feels when a pawl freehub engages, and I find the soft, near-instant feeling when I begin to pedal extremely pleasant. It makes my bike feel solid in a way I hadn’t appreciated before using Onyx hubs.

The other noticeable difference between a pawl-based freehub and Onyx’s sprag clutch is that the audible clicks or buzz of spring-loaded pawls running over the indexed driver ring is replaced by, well, nothing. The sprags are totally drag-free and silent while freewheeling forward. Many people claim to enjoy loud hubs, but having spent time absent this noise, the silence is a joy – especially while bikepacking, I am left to hear the sound of the wind, creeks, birds and the satisfying scrunch or rip of tires on dirt.

thanks to Silvia0073 for this illustration of Onyx’s silent operation.
  • Onyx Hubs Review
  • Onyx Hubs Review

Onyx Hubs Review

Far and away, the biggest benefit of Onyx’s hubs, still comes down to the freehub engagement. In the South Chilcotins, where the trails, until recently, only saw foot and hoof, the climbs are notoriously frustrating. These raw trails are narrow, janky, and just a bit steeper than one can comfortably pedal up on a loaded bike. From the seat of a bicycle, the trailbed is often obscured by fireweed or less compliant shrubbery. So, one usually can expect to be constantly on and off the bike on climbs, pedaling flat out until a pedal strike or a slipping rear tire on a too-narrow trail forces you to put a foot down. Though there are many factors at play, I have never pedaled up so many climbs on those rough, backcountry trails as on this year’s trip with Onyx hubs. I will credit at least some of that improved pedaling to the ease with which one can ratchet the pedals through technical bits of trail and time one’s pedaling with an instant-engagement freehub.

Now, so far I haven’t uttered a peep about the front hub. In many ways, a front hub is a front hub is a front hub. These days, they’re almost all just a pair of cartridge bearing pressed into an aluminum hub shell. (Shimano makes the only half-decent option that still use cup and cone bearings, but that’s not so different anyway.) But, Onyx strives for something more in their front hubs too.

Onyx Hubs Review

To start, Onyx hubs use hybrid ceramic bearings throughout. Most cartridge bearing are steel. Then there are pricier hybrid ceramic and full ceramic alternatives. Steel is easy to understand – the ball bearing and the races those ball run on are, you guessed it, steel. Full ceramic bearings use ceramic ball bearings running on ceramic races. The case for ceramic is that the material is much harder than steel, and they can be made rounder than steel bearings, and they therefore have lower rolling resistance. A common misconception is that they also last longer – but this is not necessarily the case. Hybrid ceramic bearings feature ceramic ball bearing running on a steel race. They’re cheaper than full-ceramic bearings, but since the load is more concentrated on the ball bearings than on the race, they reap most of the lower rolling resistance of full-ceramic bearings.

The problem with hybrid ceramic bearings is that the durability of a bearing is determined by its weakest link – now you’ve got really, really hard pottery balls running on a much softer race, which can tear apart the race quicker than if everything was made of softer steel. And, those really hard balls have a lower tolerance for imperfection. Given that every bearing I’ve ever destroyed (and there has been quite a lot of ’em) has been murdered by contamination, not strictly by accumulated miles, I generally advocate for nothing but well-sealed steel bearings on a bikepacking bike. Leave the ceramic bearings to race-day road bikes that might never see rain, and will certainly never see river crossings or deep mud.

All that said, on a fantasy planet where bearings could be perfectly sealed against contamination without introducing a huge amount of friction, ceramic bearings roll quicker and might even last longer. Thanks to Onyx’s exquisitely tight machining tolerances, they do well in this regard. There is no rubber seal beyond the double lip seals along the inner race of the Enduro Hybrid Ceramic bearings that Onyx employs, but the thread-on outer bearing cover is machined to an extremely close fit with the hub shell, leaving only a tiny space for water entry. Contaminants would then have to travel from the outer race of the bearing to the end of the seal on the inner race to penetrate into the inner workings of the bearing.

Onyx Hubs Review

After 8 months of riding in all conditions (including plenty of muddy wetness this spring, and a lot of dust this summer), the bearings on the front hub sound a bit drier than when they were new, but still spin smoothly. Pulling the covers off, I found a tiny bit of gunk built up on an otherwise clean-looking bearing, which is better than I can say for other bearings on my bike.

It’s no surprise that Onyx Racing Products gears their products toward racing. I appreciate the low-resistance ceramic hybrid bearings and non-contact seals, but when these bearings wear out (and they will, and that’s normal and OK) I’ll replace them with high quality steel bearings. For bikepacking, I’m generally willing to give up a bit of performance for longevity. Onyx hubs are designed to be easily serviced and adjusted by a savvy mechanic – though bearings will wear, the hubs themselves are clearly built to be passed from bike, to bike, to bike for decades. Furthermore, thanks to Onyx’s domestic (Minneapolis) machining, you can expect to easily source replacement pieces for as long as Onyx exists – whether needing a new axle or a different freehub body.

  • Onyx Hubs Review, Long-term, mountain biking
  • Onyx Hubs Review, Long-term, mountain biking

Onyx Hubs are available in 14 powder-coat colors and 9 anodized colors in a multitude of sizes and configurations. Each hub is constructed with titanium bolts and has a 5-year limited warranty. Onyx Racing Products sent this pair of hubs for review, hence the custom laser etching… However, laser etching is a free service they offer for any hub set. There are a few restrictions (multi color images, copyrighted images, etc). But, apparently, if you want our skull logo on a hub, that is an option.

Pros

  • Instant engagement freehub extends technical riding ability
  • Sprag clutch offers completely silent coasting
  • Adjustable bearing pre-load for maximum bearing life and performance
  • Available in every conceivable hub width, axle diameter, cassette interface, rotor mount, color-combo, etc.
  • Made in USA, spare parts easily available direct.

Cons

  • Pricey
  • Heavy
  • Ceramic hybrid bearings with non-contact seals offer lower rolling resistance at the cost of shorter bearing life.
  • Tested: 32 hole, 6-bolt BOOST, Front 15x110m, Rear 12x148mm XD
  • Weight: Front 225g, Rear 475g with steel XD driver
  • Price: Front $192, Rear $445
  • Finish (as tested): Anodized Black with custom laser etched logos
  • Place of Manufacture: Minneapolis, USA
  • Contact: Link

Wrap Up

Onyx hubs are very expensive. A set of Onyx hubs costs in the neighbourhood of a decent suspension fork, or a mass-produced steel frame. But, hubs – especially rear hubs – are one of the most important components on a bicycle, and also one of the most commonly under-specced and overlooked components on complete bikes. Freehub failures are trip-ending, pushing the bike sort of failures, and occur with surprising regularity on so called ‘mid-range’ hubs. Not only should it be nearly impossible for Onyx’s sprag-clutch freehub to fail, but the instant engagement offers a very noticeable performance-boost on technical trails.

I’d have as hard a time as anyone paying $192 for a front hub, so as much as I love the beautiful machining and servicability of Onyx’s front hub, I’ll probably seek a more affordable option on my next wheel build. But, I’m not sure I can live with any other rear hub. This is perhaps the greatest danger of Onyx hubs: once you’ve experienced their soft catch and instant engagement, other bikes start to feel like garbage. Now that I’m used to a totally silent freehub, the buzz of pawl-based freehubs is a major annoyance, drowning out all the sounds of the forest and the satisfying scrunch of tires on dirt. Onyx has made a life-long customer out of me. I’ll accept this fate because their hubs are built to last a lifetime.

  • nat

    Great explanation, thanks! This site is such a wealth of info. I just had a Salsa Fargo built and my mountain bike shop friend put an Onyx hub in back. I didn’t know that he was doing it! First shakedown ride yesterday. It truly is amazing for all the reasons stated above. I go off road to get into nature and silence is exactly what I seek. I like the sound of regular hubs because it makes me think “biking, yes!”…it’s a sound of play, but experiencing this hub was like when your fridge compressor stops running…all the sudden it’s so quiet. Perfect for those places away from all other noise.

  • Jake Kruse

    this comment is not directly related to onyx hubs, but it is on the top of rear hubs for bikepacking. i have experienced the dreaded freehub failure once while in the gila national forest of new mexico on the CDT. as stated, it was a trip ending mechanical. i had my wheel rebuilt with a DT Swiss 350 hub. it is built with the stock 18 tooth ratcheting engagement. i was curious if anyone could comment on the upgrades available (36t, 54t) in terms of reliability? in theory, would more points of engagement make the hub more durable and less prone to failure in the long run?

  • I am sure others will comment, and many will likely say that DT350s are reliable (although I have had a bad experience too). Others’ short lists would likely include Phil Wood hubs, which are touted as highly reliable, but they only have a 40t drive ring. Chris King’s hubs have a 72t ring and are supposedly pretty good (although I can’t claim any experience with them). I personally like ultra-high engagement hubs, such as this one or the 3° Industry Nine torch. I have been using the I9s on my FS trail/bikepacking bike for over a year without issue.

  • Dt350 are definitely a good choice for their reliability, but as you noted, the 18 tooth ratchet has very low engagement. I know the 54t ratchet is definitely more prone to failure, but it’s really easy to swap out the star ratchets in the field, with no tools, so you can always keep your old 18t ratchets in the repair kit. If doing it from scratch, the Onyx hub is not that much more expensive than a DT350 plus the $100 star ratchet upgrade, so I’d recommend going that route for people who haven’t already got a DT hub.

  • I’m a big fan of the DT star ratchet system for expedition bikes. As Skyler notes, it’s super easy to change a star ratchet in the field, and the spare ratchets don’t take up much space in your kit. While there are reliable spring and pawl hubs – mostly the MUSA options Logan mentions – I still prefer the DT system in practice and have over the past couple years invested in DT hubs for most of the bikes in our house.

    Personally I don’t mind “low” engagement freehubs, so the 20º engagement of the 18 tooth ratchet isn’t a big deal to me. Of the five rear wheels with star ratchets in our house, only one has the 36 tooth ratchet. All the others are on 18 tooth ratchets. The teeth on the 36 tooth ratchet are still reasonably deep, but the teeth on the 54 tooth ratchet are indeed much finer and shallower. You’ll be carrying a spare ratchet if you travel, so buy whatever one you like as an upgrade and put the stock one in your parts kit.

    I’ve blown up plenty of freehubs, but I’ve only blown up one DT star ratchet hub, and that was on a brand new (media test) mountain bike in Sedona, climbing steep slickrock. We traced that back to an incorrect spring installation, so mechanic error and not the fault of the hub itself.

  • Jake Kruse

    all right, so you suggest the shallower interfaces on the ratchet upgrades weaken the system while increasing performance? that is kind of what i was hypothesizing as well, but without much evidence to go on. 18t engagement works fine for me as well. maybe 36t is the sweet spot? thanks all.

  • Michael

    I almost bought a set of Onyx hubs as I had tired over the racket made from most mtb hubs but the price and weight kept me away. Recently I grabbed a rear https://project321.com hub primarily because of the nearly silent magnetic pawl design, that combined with the super tight engagement and light weight (about the same as any lightweight regular hub) has made this my favourite hub to date. It is however also fairly pricy but the silence alone is worth it the engagement and weight are icing.

  • Ben

    I have had the same experience as Skyler, the reviewer: Onyx hubs are incredible, and once you try them it’s seriously hard to go back to other brands. This is partly because of the amazing, near-instant engagement (which *will* save you on some high-torque climb when every last bit of engagement makes the difference for cleaning it,) and partly because these hubs expose just how much drivetrain noise we’ve grown accustomed to. It’s amazing being able to actually hear the sounds of the forest again, and honestly, that alone makes them worth the price of admission. I’m on my second set (FS and hardtail) and will likely put another on my gravel bike soon too.

  • mikeetheviking

    I’ve been wanting an Onyx hub bad….

    I am also seriously interested in the DT 350… Having blown a freehub far away from the trailhead this year makes the DT “tool less/quick change” ratchet assemblies appealing to me.

    But when I add up the costs I could have an Onyx for relatively 100 bucks more, plus a custom color.

    Not to beat a dead horse but I wish DT could find a way to lower the price of the ratchet assy’s… I feel this would help DT really take ownership of this market.

  • Michael

    I couldn’t stand the 18t DT Swiss from an engagement point of view on my full suspension mtb, I blame its low engagement on long term injury where I needed to push and there was nothing to push against! I’m fine with it on my commuter. I happily recommend the 350 version as a quiet and cheapish hub for folks not putting much pressure on them. I think it’d be ok on my bike packing rig too but I’d at least run the 36t. A friend did recently blow up his 350 mtb’ing but he rides pretty hard and almost daily.

  • fauxpho

    Oh, the tensions that could develop in a rear hub discussion. Only politics could be more opinionated! :)
    So, first off, I love the Onyx hubs and I’m a big fan of the sprag clutch. No arguments there. Loved reading the review. But . . .
    First, I am skeptical that 99.9% of all bike hubs use pawls. Do you really think DT has less than 1/10 of 1% market share? Even if you consider the ~ 100M bikes made each year, a fraction of those use freehubs. I’m not arguing that pawl designs aren’t the vastly dominant method, but 99.9% might be hyperbole. A nitpick.
    Next, I’m surprised that “instant” engagement is the calling card for Onyx. Its a key feature, no doubt. But reliability should be a dominant decision criteria for backpacking, and (based on my anecdotal awareness) the Onyx is among the most reliable. Yet that’s not mentioned as a “pro.”??
    And that brings me to my main point: the fetish-ization of points of engagement. Lets consider the math of a 175mm crank arm rotation. 1deg engagement means (in linear terms) you engage every 3mm on the pedal arc. 10deg means 30mm. Not a great distance to backpedal in a rock garden. Yet I consistently hear/see people talk about how dramatic the difference is . . . can’t do this climb, caused this crash, etc, etc. Because your pedal moved 30mm instead of 3mm?? In terms of time, at a cadence of 50, the advantage of 1deg over 10deg is only 3/100ths of a second. Is that amount of time really the deal breaker when riding technical terrain? You recognized an obstacle in 1/100th of a second, but crashed because it took you another 3/100s to initiate a power stroke? Surely your skill and eye/foot coordination (recognizing and anticipating obstacles and pedal position, balance, etc) are a far more significant contributor, no?
    I’ve ridden 18T ratchets in all kinds of terrain, sustained rock gardens, off-camber side-slope crap, what-have-you, and cleared all sorts of trails that left others standing. Not that I’m some guru. Rather, I just find the other variables (line choice, gear choice, weight shifting, etc) to be far greater issues. I’ve used 36T and I notice (and like) the difference, but it quickly diminishes beyond 36T/10deg. I’ve ridden Onyx. It feels very, VERY cool. I like it. Love it even. But I can’t objectively say it has enabled me to ride anything that I couldn’t on a more typical hub.
    ESPECIALLY in the context of bikepacking. I mean, where on the GDMBR do points of engagement matter? Where on the Baja Divide does POE matter? Nowhere, at least in my experience. Even on a technical outing like the AZT, I have never once been held back by POE. On a trials bike? Hell yes, Onyx or nothing. A world cup start-gate race in BMX or 4X, sure. But us dopy dirt road and trail bike touring types? C’mon.
    Yet I perceive I’m in a minority on this topic, so let the haters start to hate.

  • Star ratchets and pawls are basically the same principle. But sure, might be hyperbole. Then again, the massive majority of bikes in the world are cheap, department store-style bikes. Freewheels use pawls too. But yeah, you got me. I have no clue what actual fraction of hubs use ratchets… Pure estimation.

    On the GDMBR and maybe the Baja Divide, I agree, engagement doesn’t matter (never seen the Baja Divide though, so I shouldn’t speak to that). You don’t really need that level of precision on roads or even rough two-track. If I’m spinning pedals without pause or adjustment for hours, a few mm of “slack” won’t matter.

    On the AZT, it certainly did matter for me, at least in the technical southern half. 30mm is a hell of a lot of slack when you can only afford to move your feet 50mm at a time… I definitely notice a massive difference in engagement on tough, technical backcountry trails. In the Chilcotins, it seriously matters. Believe me if you want – I think I’m pretty perceptive of these things.

    But yeah, I think we can both agree that Onyx hubs have appeal on many levels, especially in terms of reliability. You’re right that reliability deserves a bullet point in the list of “pros”. It’s always a little hard to commit to making such statements, even after a whole season of riding – who’s to say I won’t break something tomorrow. That’s what happens every time I comment positively on the durability of pedals: they explode a month later.

  • I’ll add one point regarding the point of view of this review. Personally, and I think I speak for many people here, my trail bike — which spends a lot of time on very rooty and rocky, technical single track — doubles as my bikepacking rig. They are one in the same. This hub, as well as the i9 which I reviewed, are for people who fit into that niche. I am not saying that folks can’t or wouldn’t use either to build a bike particularly for the TD, but my point is that many of our reviews come from that perspective.

    For me having a ultra-high engagement hub has been a game changer. No, it hasn’t prevented accidents, but it has improved my technical riding and made it that much more enjoyable.

  • shannon

    Building up a +1 slack ripper w/ the potential to bikepack, I am slipping down the rear hub bunny hole to hell: great problem to have “what high end bike hub should I buy”. I have CK on a singlespeed that has been great for 5 years, and love the abilty to ratchet over techy stuff with the high POE, which makes it hard to step down to a lower POE when thinking of buiding a fun/packing rig (espescially when I dont even pack yet). My question to you experts: How much does preventive maintenance play into hub failure while on a trek?

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