Onyx Fat Bike Rear ISO 6 Bolt Disc Hub
The Onyx fat bike hub brings the sprag clutch to fat-bike spacing: instant engagement with no teeth to skip between and total silence when coasting, in a hubshell spaced for 150mm front and 177 or 197mm rear thru-axles, with centerlock or 6-bolt rotor mounts, machined and anodized in Minnesota. A fat tire at 6 psi has so much grip that any dead stroke on a snow climb is lost momentum, and the Onyx has none. This page covers the Onyx Fat Bike Rear ISO 6 Bolt Disc Hub.
The Onyx fat bike hub is sold here only inside a wheel we build. Choose the rim, spokes and nipples in the configurator and the finished wheel ships from Georgia laced, tensioned and trued by hand.
Design and construction
Fat-bike spacing asks a lot of a hub: 150mm at the front and 177 or 197mm at the rear puts the flanges a long way apart and the bearings under a wide, twisting load. Onyx machines the shell and anodises it in Minnesota for those widths, with centerlock or 6-bolt rotor mounts and the same sprag clutch as the rest of the range.
Silence is worth more in winter than anywhere else. A freehub packed with snow and grit is the one that starts skipping, and a clutch with no teeth has nothing to skip over.
How it rides
An Onyx fat hub engages the moment you push, which on snow and sand is the difference between cleaning a climb and walking it, and it coasts in silence through the woods. The labyrinth seal keeps slush and salt out and the hardened stainless driver shrugs off winter. It is the fat-bike hub for riders who want the best.
Specifications
| Position | Rear |
|---|---|
| Axle width | 170, 177, 190, 197 mm |
| Driver bodies | Shimano HG 8,9,10,11 & Road 12spd (Aluminum) (+$45), SRAM XD 10,11 & MTB 12spd (Aluminum) (+$45), Shimano Micro Spline 12spd (Aluminum) (+$45), Shimano HG 8,9,10,11 & Road 12spd (Steel), SRAM XD 10,11 & MTB 12spd (Steel), Shimano Micro Spline 12spd (Steel) |
| Drillings | 32h, 36h |
| Spoke head | J-bend |
| Brake | 6-bolt disc |
| Left flange diameter | 60 mm |
| Right flange diameter | 60 mm |
| Spoke hole diameter | 2.6 mm |
| Weight | 459g |
| Material | Aluminum |
| Finishes | baby blue pc, black ano, black aura pc, black matte ano, blue ano, blue candy pc, clear ano, gold ano, green ano, green anti freeze pc, green florescent pc, green kawasaki pc, orange ano, orange florescent pc, pink ano, pink florescent pc, purple ano, purple candy pc, red ano, red candy pc, turquoise ano, white pc, yellow cardinal pc, yellow florescent pc |
This version
This version is the 6-bolt hub in the axle standards listed above, drilled for 32h, 36h, about 459g, in baby blue pc, black ano, black aura pc, black matte ano, blu. Those are the only things that differ between the versions of the fat bike; the shell, bearings and seals are the same.
Six-bolt is the original disc mount and still the most universal: any ISO 6-bolt rotor from any brand bolts straight on, rotors are cheap and easy to find anywhere, and the six-bolt flange is a robust, simple interface that has been on mountain bikes for twenty-five years. Centerlock rotors do not fit it.
Sizes, fit and compatibility
The Onyx Fat Bike Rear ISO 6 Bolt Disc Hub comes in the drillings listed on this page in 150mm front and 177 or 197mm rear thru-axle spacing with the rotor and driver options shown in the configurator. J-bend spokes in any gauge; we build most fat wheels with Sapim Race or DT Competition spokes and brass nipples.
It pairs with the HED Big Deal and Big Aluminum Deal, DT Swiss BR 710, Sun Ringle Mulefut and Surly fat rims in the catalog. Pick fat bike as your bike type in the configurator and it recommends a spoke count and lacing pattern for the offset.
Build a wheel around it
Offered for fat bike builds in our Custom Wheel Program. Start with the Onyx Fat Bike Rear ISO 6 Bolt Disc Hub and the configurator pins it for you, then checks each choice you make against it.
How Onyx tests its hubs
Onyx Racing Products hubs are made in the USA by a division of Christianson Systems in Minnesota; in a 2020 interview the company described itself as "Minnesota made and owned". Hub shells are machined from 7075 aluminum (retailer listings cite 7075-T651 with heat-treated stainless steel and titanium hardware), and Onyx's European distributor states Onyx freehub units "are made out of high-grade 7075 aerospace-grade aluminum in the USA". Bearings are hybrid ceramic on the Classic line and an upgrade option on Vesper; the distributor states "Since early 2025 all Onyx hubs have been assembled with high-quality Japanese EZO bearings." Onyx specifies a grease service temperature range of -58°F (-50°C) to 248°F (120°C). It publishes no bearing-cycle, salt-spray, ISO 4210 or load-test figures. Onyx's specifications state radial lacing is not permitted on any Onyx hub and set a maximum spoke tension of 120 KgF.
the patented sprag clutch is a one-way clutch of cams between two races, giving instant engagement, instant disengagement when coasting and silent operation; BMX hubs use a single-row sprag assembly, mountain, road and gravel hubs a double-row assembly. Onyx publishes no numerical torque capacity; its distributor states Classic hubs "are e-bike approved for bikes that have a mid-drive unit with a peak power output of up to 1500W."
Onyx's videos
Inside the Onyx shop
Certifications
- Made in USA (Minnesota) — Onyx states it is "Minnesota made and owned"; retailer and distributor listings state "Made in the USA" (source)
- 5-year limited hub warranty — Hub 5 years to original owner; sprag clutch 1 year against manufacturing defects; wheel builds 1 year (source)
- E-bike approval (Classic hubs) — Distributor states Classic hubs are e-bike approved for mid-drive units with peak power output up to 1500W (source)
Sources on Onyx's site:
- Onyx Racing Products - Tech (site returned 403 at time of research)
- Onyx Racing Products - Limited Warranty (U.S. Only)
- Onyx Racing Products Wheels - Warranty
- November Bicycles: In their own words - Onyx Racing Products (April 17, 2020)
- Onyx Hubs Europe - Technology
The figures, certificates and media above are Onyx's own. ProWheelBuilder does not run these tests; our part is the wheel we build on the hub.
Building it at ProWheelBuilder
Onyx makes the fat bike; ProWheelBuilder is an independent custom wheel builder in Georgia and not the manufacturer. Spokes are cut from the ERD we measure on the actual rim, the wheel comes up in stages on a tensiometer, and it is stress-relieved and trued before it goes in the box; tape and a valve go on if you ask.
The configurator filters to what fits, crosses out what is not made, and prices the build as you go.
Warranty
Onyx's warranty. Onyx Racing Products covers its hubs under a five-year limited warranty against defects in materials and workmanship.
ProWheelBuilder. Wheels we build around this part are covered by our own one-year warranty alongside the maker's. Within the year: broken spokes replaced regardless of cause, and the labor on the wheel - truing, re-tensioning or a complete rebuild - included. A manufacturer-covered rim or hub failure is a claim we make and manage for you; one they will not cover is answered with an eligible replacement at 25% off retail. Shipping each way is yours. Parts you supply yourself fall outside it.
Full terms are on our Policies & Warranty page.
Fat Bike Rear ISO 6 Bolt Disc Hub questions
Will my rotors fit this hub?
This is the 6-bolt version: any ISO 6-bolt rotor bolts straight on with six T25 bolts, which is still the most common and the easiest rotor to replace anywhere. Centerlock rotors do not fit it - for those, take the centerlock version of the same hub, listed separately.
What spacing is the Onyx fat bike hub?
150 x 15mm front and 177 or 197 x 12mm rear, selectable in the configurator.
Is the Onyx fat hub good for winter?
Yes. The labyrinth seal and hardened stainless driver handle slush and salt; a clean and regrease each spring keeps it happy.
Which drivers fit?
Shimano HG, SRAM XD and Shimano Micro Spline, selectable in the configurator.
Is it silent like other Onyx hubs?
Yes. The sprag clutch has no teeth, so coasting is completely silent.
Is ProWheelBuilder the manufacturer of the Onyx Fat Bike Rear ISO 6 Bolt Disc Hub?
No. Onyx makes the hub. ProWheelBuilder is an independent custom wheel builder in Georgia that builds it into a finished wheel to your spec.
Which axle spacing does it fit?
170, 177, 190, 197 mm. Measure between the inside faces of your dropouts if you are unsure, or text us.
Not sure? Text or leave a voicemail on 470-253-0929 or email info@prowheelbuilder.com — you will be talking to the people who build the wheels.
