Onyx MTB SS Rear Centerlock Disc Hub
The Onyx Classic SS is the Onyx Classic with a dedicated single-speed driver: the heaviest-duty sprag clutch Onyx makes, instant and silent, with the extra sprag rows and bearing capacity that let it take the abuse a single-speed rider puts through a rear wheel standing on every climb. Machined and anodized in Minnesota, with a short splined driver and spacers for chainline, centerlock or 6-bolt rotor mounts and Boost or standard spacing. This page covers the Onyx MTB SS Rear Centerlock Disc Hub.
The Classic SS is built to order here. Choose the rim, spokes and nipples in the configurator; the wheel leaves Georgia laced, tensioned and trued.
Design and construction
The Classic SS pairs the heaviest-duty sprag clutch Onyx makes with a dedicated single-speed driver. The extra sprag rows and bearing capacity exist for exactly this use: a single-speed rider stands on every climb, and every one of those efforts goes into the hub without a derailleur or a cassette shift to soften it.
Machined and anodized in Minnesota, in a catalog of more than twenty colors plus a limited release each month.
How it rides
A Classic SS engages the instant you stomp with no dead stroke and coasts in silence, and its extra sprag rows mean it never skips under the torque a single speeder produces. It is heavier than the Vesper SS and stronger; for a single-speed trail bike ridden hard or a heavy rider, the Classic SS is the Onyx hub we recommend.
Specifications
| Position | Rear |
|---|---|
| Axle options | QR 5x135mm Rear, Bolt On 10x135mm Rear, Thru Axle 12x135mm Rear, Thru Axle 12x142mm Rear, Thru Axle 12x148mm Boost Rear |
| Driver bodies | 1 Single Speed Shimano HG Cassette (Aluminum) (+$45), 2 Single Speed Shimano HG Cassette (Steel) |
| Drillings | 28h, 32h, 36h |
| Spoke head | J-bend |
| Brake | centerlock disc |
| Left flange diameter | 50 mm |
| Right flange diameter | 50 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 |
Which version this is
Version notes. Centerlock rotor mount, QR 5x135mm, Bolt On 10x135mm, Thru Axle 12x135mm, Thru Axle 12x142mm and more, 28h, 32h, 36h, about 454g, in baby blue pc, black ano, black aura pc, black matte ano, blu. If your frame or fork uses a different standard, the other versions of the Classic single speed on this site cover it.
This is the centerlock Classic single speed: the rotor sits on a spline and a lockring holds it, which saves weight over six bolts and makes swapping rotors a one-tool job. If your rotors are 6-bolt, a centerlock adapter fits them, or choose the 6-bolt version of the same hub.
Sizes, fit and compatibility
The Onyx MTB SS Rear Centerlock Disc Hub comes in the drillings listed on this page with the axle and rotor options shown in the configurator. The single-speed driver takes standard splined cogs with spacers to set the chainline. J-bend spokes in any gauge; we build most single-speed wheels with Sapim Race or Strong spokes or DT Competition and brass nipples.
It pairs naturally with any trail rim in the catalog that matches its drilling. Pick single speed as your bike type in the configurator and it recommends a spoke count and lacing pattern.
Build it with us
We build this hub to order. Open the Custom Wheel Program with the Onyx MTB SS Rear Centerlock Disc Hub already selected and pick the parts around it; it is offered for gravel and road disc, track and road single-speed and MTB single-speed builds, and the configurator will not let you assemble a combination we would not build.
Onyx's testing and certifications
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 Classic single speed; ProWheelBuilder is an independent custom wheel builder in Georgia and not the manufacturer. The build is the same every time: measured ERD, spokes cut to the half millimeter, staged tensioning with a gauge, stress relief, a final true, and tubeless tape and a valve on request.
The configurator shows only rims and spokes that fit the Classic single speed drilling, strikes through combinations that are not made, and prices the wheel live.
Warranty
Onyx's warranty. Onyx Racing Products covers its hubs under a five-year limited warranty against defects in materials and workmanship.
ProWheelBuilder. Built into a wheel by us, this part is covered by our own one-year wheel warranty on top of the maker's. For a year we replace broken spokes whatever caused them, and we cover the labor on the wheel - truing, re-tensioning, a rebuild if it needs one. If a rim or hub fails and its maker covers it, we run that claim for you; if the maker says no, you get an eligible replacement rim or hub at 25% off retail. You pay the shipping each way. Wheels built from parts you send us are excluded.
Full terms are on our Policies & Warranty page.
MTB SS Rear Centerlock Disc Hub questions
Will my rotors fit this hub?
This is the centerlock version, so a splined centerlock rotor drops on and a lockring holds it - one tool, no six bolts to torque or lose. If your rotors are 6-bolt they will fit with a centerlock adapter, or take the 6-bolt version of the same hub, which is a separate listing.
Which spokes and nipples suit the Classic single speed?
For most riders a double-butted spoke such as Sapim Race or DT Competition with brass nipples; lighter riders can go to Sapim Laser or CX-Ray. The configurator recommends a gauge and count for the Classic single speed from your bike type and weight.
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.
Is ProWheelBuilder the manufacturer of the Onyx MTB SS Rear Centerlock 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.
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.
