Onyx Vesper Rear ISO 6 Bolt Disc Hub
The Onyx Vesper is the hub for riders who want instant engagement and silence at the same time. Onyx Racing Products, in Minnesota, uses a sprag clutch instead of pawls or ratchets: a ring of tilting steel sprags that lock the moment you pedal, with no teeth to skip between, no clunk and no freehub buzz at all. The Vesper is the light version of that idea, about 23% lighter than the Onyx Classic, with a single-and-a-half row of sprags, a common axle that makes driver swaps cheap, and centerlock or 6-bolt rotor mounts. This page covers the Onyx Vesper Rear ISO 6 Bolt Disc Hub, the mountain-bike version in Boost spacing.
The Vesper 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
A sprag clutch has no engagement points because it has no teeth. Each sprag is a small hardened steel cam held lightly against the race by a spring; pedal forward and every sprag tilts and wedges instantly, coast and they release just as fast, with nothing to click. Onyx uses a heat-treated hardened stainless driver, a labyrinth seal between driver and shell, and an adjustable side load so the hub can be set up for the rider. The Vesper keeps all of that with fewer sprag rows than the Classic, which is where the weight saving comes from, and Onyx rates it for pedal bikes rather than e-bikes.
The shell is machined and anodized in Minnesota in a range of colors, with J-bend flanges in 28 and 32 hole and drivers for HG, XD and Micro Spline that swap on the common axle.
Onyx designs, machines and assembles in the USA, and treats color as part of the product rather than a finishing option: more than twenty anodized colors are cataloged, with a further limited color released each month that is gone once it sells through.
How it rides
A Vesper is silent. Coasting makes no sound at all, which takes a few rides to get used to, and pedalling engages the instant you push with none of the tick-tick of a high-count pawl hub. On a technical climb or a trials move there is no dead stroke, and because the clutch locks across its whole face there is no harshness either. The Boost rear weighs around 370 to 410 grams depending on driver, which is competitive with the light end of the boutique hub market.
We build the Vesper for cross-country, trail and enduro wheels; for downhill and e-bikes the Onyx Classic is the heavier-duty version.
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), Campagnolo 9,10,11 & 12spd, Campagnolo N3W 10,11,12 & 13spd, Shimano Micro Spline 12spd (+$75), SRAM XDR 10,11 & Road & MTB 12spd |
| Drillings | 24h, 28h, 32h |
| 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 | 409g |
| 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 Vesper versions: 6-bolt rotor mount, QR 5x135mm, Thru Axle 12x135mm, Thru Axle 10x135mm, Bolt On 10x135mm and more, 24h, 28h, 32h drilling, about 409g, 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 Vesper: 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 Vesper 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 Vesper wheels with Sapim Race, D-Light or CX-Ray spokes or DT Competition and brass nipples.
It pairs naturally with Reserve, Nox, We Are One, ENVE, DT Swiss, Race Face and Stan's rims that match its drilling. Pick your bike type and weight 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 Vesper Rear ISO 6 Bolt Disc Hub already selected and pick the parts around it; it is offered for gravel and road disc, mountain bike and fat bike builds, and the configurator will not let you assemble a combination we would not build.
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
Everything in this section is published by Onyx. ProWheelBuilder is the wheel builder, not the tester, and the hub reaches us as the maker ships it.
Building it at ProWheelBuilder
Onyx makes the Vesper in Minnesota; 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. If we lace this into a wheel for you, that wheel also carries ProWheelBuilder's own one-year warranty, which covers broken spokes regardless of cause and all wheel-related labor, including truing and rebuilding, for a year from purchase. Where a rim or hub is covered by its maker, we make the manufacturer's claim for you and coordinate it; where it is not, we offer an eligible replacement rim or hub at 25% off current retail. Shipping to and from us is the customer's. This cover does not extend to wheels built from components you supply yourself.
Full terms are on our Policies & Warranty page.
Vesper 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.
How does a sprag clutch work?
A ring of tilting hardened-steel cams wedges against the race the instant you pedal and releases the instant you coast. There are no teeth, so engagement is instant and coasting is silent.
Vesper or Onyx Classic?
Vesper for cross-country, trail and enduro where weight matters; Classic for downhill, e-bikes and the heaviest duty, with more sprag rows.
Which drivers fit the Vesper?
Shimano HG, SRAM XD and Shimano Micro Spline, swappable on the common axle and selectable in the configurator.
Is the Vesper e-bike rated?
No. Onyx rates the Vesper for pedal bikes; the Onyx Classic is the e-bike and downhill hub.
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.
