Onyx MTB Rear ISO 6 Bolt Disc Hub
The Onyx Classic is the original Onyx hub and the heaviest-duty version of the sprag clutch: instant engagement with no teeth to skip between, total silence when coasting, and enough sprag rows and bearing capacity that Onyx rates it for e-bikes and downhill. Machined and anodized in Minnesota, the Classic has a heat-treated hardened stainless driver, a labyrinth seal between driver and shell and an adjustable side load, with centerlock or 6-bolt rotor mounts and Boost or Superboost spacing. This page covers the Onyx MTB Rear ISO 6 Bolt Disc Hub.
The Onyx Classic comes from us only as a finished wheel: pick the rim, spokes and nipples, and we lace, tension and true it by hand in Georgia before it ships.
Design and construction
The Classic is the original Onyx and the heaviest-duty version of the sprag clutch, with more sprag rows and more bearing capacity than the Vesper - enough that Onyx rates it for e-bikes and downhill. Machined and anodized in Minnesota, it is the hub to choose when the loads are high rather than when the grams matter.
Everything is designed, machined and assembled in the USA, which is also why a Classic can be rebuilt rather than retired: the sprags, bearings and seals are serviceable parts.
How it rides
A Classic engages the instant you push and coasts in silence, like every Onyx, and it does it under an e-bike motor or a downhill bike's landings without complaint. It is heavier than the Vesper, which is the price of the extra sprag rows and bearing capacity. For cross-country, trail and enduro the Vesper is lighter; for downhill, park and e-MTBs, the Classic is the Onyx hub we recommend.
Specifications
| Position | Rear |
|---|---|
| Axle options | QR 5x135mm Rear, Thru Axle 12x135mm Rear, Thru Axle 10x135mm Rear, Bolt On 10x135mm Rear, Thru Axle 12x142mm Rear, QR 5x141mm Boost Rear, Thru Axle 12x148mm Boost Rear, Thru Axle 12x150mm Rear, Thru Axle 12x157mm Super Boost Rear |
| 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 | 24h, 28h, 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 | 454g |
| 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 |
About this listing
What sets this listing apart from the other Classic versions: 6-bolt rotor mount, QR 5x135mm, Thru Axle 12x135mm, Thru Axle 10x135mm, Bolt On 10x135mm and more, 24h, 28h, 32h, 36h drilling, about 454g, in baby blue pc, black ano, black aura pc, black matte ano, blu. Pick the one that matches your frame and rotor and the rest of the hub is identical.
This is the 6-bolt Classic: the rotor bolts to a flange with six T25 bolts, which is the mount most mountain and gravel rotors still use and the easiest to find a rotor for on the road. If you run centerlock rotors, choose the centerlock version of the same hub instead.
Sizes, fit and compatibility
The Onyx MTB Rear ISO 6 Bolt Disc Hub comes in the drillings listed on this page with the axle, rotor and driver options shown in the configurator. J-bend spokes in any gauge; we build most Classic wheels with Sapim Race, Strong or CX-Sprint spokes or DT Competition and Alpine III and brass nipples.
It pairs naturally with the WTB HTZ, DT Swiss FR 541 and HX 531, Race Face ARC Heavy Duty, Stan's Flow EX3 and the carbon gravity rims in the catalog. Pick downhill or e-bike as your bike type in the configurator and it recommends a spoke count and lacing pattern.
Build it into a wheel
This hub is live in our Custom Wheel Program for gravel and road disc, mountain bike and fat bike builds. Start a build with the Onyx MTB Rear ISO 6 Bolt Disc Hub and the configurator opens with this exact hub pinned at the top of the Onyx list — you choose the rest of the parts and it validates every combination as you go.
Testing, standards and warranty at Onyx
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.
Warranty and service: Onyx hubs carry a 5-year limited warranty to the original owner, non-transferable; the sprag clutch is guaranteed against manufacturing defects for one year, and Onyx wheel builds carry a 1-year limited warranty. The European distributor recommends "a seasonal check-up 2-3 times a year".
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
Onyx publishes those results; ProWheelBuilder builds the hub into a wheel and does not test it in a lab.
Building it at ProWheelBuilder
Onyx makes the Classic; ProWheelBuilder is an independent custom wheel builder in Georgia and not the manufacturer. We measure the rim before we cut a spoke, bring the wheel up in three or four rounds with a gauge, stress-relieve it between rounds and true it last, then tape it and fit a valve if you want it tubeless.
Only compatible hubs and spokes appear in the configurator, impossible combinations are struck through rather than hidden, and the price is live.
Warranty
Onyx's warranty. Onyx Racing Products covers its hubs under a five-year limited warranty against defects in materials and workmanship.
ProWheelBuilder. Any wheel we build on this part carries ProWheelBuilder's one-year warranty in addition to the manufacturer's. Broken spokes are replaced for a year whatever the cause, and all wheel-side labor is included - truing, re-tensioning, rebuilding. Where the maker covers a failed rim or hub we handle that claim for you; where they decline, an eligible replacement comes at 25% off current retail. The customer covers shipping in both directions. Components supplied by the customer are not covered.
Full terms are on our Policies & Warranty page.
MTB 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.
Classic or Vesper?
Classic for downhill, e-bikes and the heaviest duty; Vesper for cross-country, trail and enduro where its 23% lower weight matters.
Is the Onyx Classic e-bike rated?
Yes. It is one of the few instant-engagement hubs rated for e-MTB use.
Which drivers fit the Classic?
Shimano HG, SRAM XD and Shimano Micro Spline, selectable in the configurator.
Why is a sprag clutch silent?
There are no teeth. Hardened steel cams wedge against a smooth race when you pedal and release when you coast, so there is nothing to click.
Which axle spacing does it fit?
QR 5x135mm Rear or Thru Axle 12x135mm Rear or Thru Axle 10x135mm Rear or Bolt On 10x135mm Rear or Thru Axle 12x142mm Rear or QR 5x141mm Boost Rear or Thru Axle 12x148mm Boost Rear or Thru Axle 12x150mm Rear or Thru Axle 12x157mm Super Boost Rear. Measure between the inside faces of your dropouts if you are unsure, or text us.
Does it need special spokes?
No. It takes standard J-bend spokes, which the configurator offers in every gauge and finish we stock.
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.
