Velo Orange Chronos Boost Rear ISO 6 Bolt Disc Hub
The Velo Orange Chronos Boost Rear ISO 6 Bolt Disc Hub is the Chronos for Boost mountain bikes and bikepacking frames: 148x12mm thru-axle, a floating 36-tooth ratchet, a freehub body that comes off by hand, 58mm flanges and large sealed cartridge bearings, at 307 grams with a Shimano body.
It is drilled 28 or 32 hole in silver or black, with Shimano HG, Shimano Micro Spline, Campagnolo or SRAM XD freehub bodies. This page covers the Boost 148 rear, built to order in Georgia.
Design and construction
Boost moves both rear flanges outward. On this hub they sit 37.8mm left and 19.3mm right of center, against 34.6 and 17.3 on the 142mm Chronos disc rear. The wider drive-side flange is the important number: it reduces dish, brings the two sides closer in tension and gives a stiffer, stronger rear wheel, which is why Boost became the mountain bike standard.
Inside, it is the Chronos drivetrain: a floating ratchet instead of pawls, 36 teeth stock for engagement every 10 degrees, and a 54-tooth ratchet sold by Velo Orange for quicker pickup on technical climbs. Micro Spline and SRAM XD bodies cover modern 12-speed mountain cassettes.
How it rides
On a loaded bikepacking bike or a steel hardtail this is a hub that keeps working a long way from help. The bearings are sealed against mud and water, the ratchet is built for torque in a low gear, and a drive-side spoke can be replaced on the trail by pulling the freehub off by hand.
Riders who climb technical terrain and want faster engagement can fit Velo Orange's 54-tooth ratchet later. For loaded bikepacking we suggest 32 hole; 28 hole suits a lighter trail wheel.
Specifications
| Position | Rear |
|---|---|
| Brake | ISO 6-bolt disc |
| Axle | Thru-axle 12x148mm Boost (axle not included) |
| Freehub bodies | Shimano HG, Shimano Micro Spline, Campagnolo or SRAM XD, chosen in the configurator; the body is included in the price |
| Ratchet | Floating ratchet, 36t stock (54t sold by Velo Orange) |
| Drillings | 28h, 32h |
| Spoke head | J-bend |
| Flange diameter | 58 mm, both sides |
| Left center-to-flange | 37.8 mm (rotor side) |
| Right center-to-flange | 19.3 mm |
| Weight | 307g with Shimano body |
| Bearings | Sealed cartridge |
| Material | Aluminum |
| Finishes | silver, black |
About this listing
This listing is the Boost Chronos rear: 148x12mm thru-axle only, 6-bolt rotor, 28 or 32 hole, about 307g with a Shimano body.
A 135mm quick-release or 142mm thru-axle frame takes the Chronos Rear ISO 6 Bolt Disc Hub instead. The matching front for a Boost fork is the Chronos Boost front, 15x110.
Sizes, fit and compatibility
Boost rear spacing is 148mm with a 12mm thru-axle, standard on most mountain bikes made since about 2016 and on many bikepacking frames. Check the frame or its axle if you are unsure; Velo Orange does not include the thru-axle.
Micro Spline takes Shimano 12-speed mountain cassettes, SRAM XD takes SRAM Eagle, Shimano HG takes HG cassettes through 11-speed, and Campagnolo is offered too; all are the same price. It builds with standard J-bend spokes on a mountain bike disc rim such as the Velo Orange Orbital; choose mountain bike or single-speed mountain as the bike type and the configurator recommends spoke count and lacing.
Build a wheel around it
Offered for mountain bike and MTB single-speed builds in our Custom Wheel Program. Start with the Velo Orange Chronos Boost Rear ISO 6 Bolt Disc Hub and the configurator pins it for you, then checks each choice you make against it.
Velo Orange's factory, testing and warranty
Velo Orange visited its Taiwan partner factories in 2025 and wrote up the hub maker, whose new hubs were then in early sample testing. The process it describes: aluminum shells and freehub bodies cold-forged in-house on presses of up to 650 tons, CNC machining afterward and the 6-bolt rotor mount, and spoke holes punched instead of drilled so the hole has a chamfer that Velo Orange considers ideal for a J-bend spoke elbow. Its quality-control claim is simple: every hub is checked for smoothness and play before it goes in the box.
On the Chronos rears Velo Orange has moved from pawls to a floating ratchet, which it says gives excellent engagement and handles high torque loads with ease; 36 teeth are stock, and a 54-tooth ratchet is sold as a replacement part for more engagement off-road. The end caps and freehub body come off by hand, which Velo Orange describes as tool-free maintenance that turns a roadside drive-side spoke replacement into a minor detour.
Velo Orange does not publish impact, fatigue or ISO test results for the Chronos. On warranty it states that defective parts can be exchanged for one year from the purchase date, with proof of purchase.
From Velo Orange
Sources on Velo Orange's site:
- Chronos Rear Disc Hub, Boost
- Replacement Chronos Rear Hub Ratchets
- Behind the Scenes: Velo Orange's Factory Visits in Taiwan
- Velo Orange Hubs collection
The figures and photos above are Velo Orange's own; our part is the wheel we build around the hub.
Building it at ProWheelBuilder
We do not make the Chronos Boost rear, Velo Orange does. ProWheelBuilder is an independent custom wheel shop in Georgia: we measure, cut spokes to length, lace by hand, tension in stages with a meter, stress-relieve the wheel and finish it true, round and correctly dished.
In the configurator the options narrow to what fits this hub, impossible combinations are shown struck through, and the price is live.
Warranty
Velo Orange's warranty. Velo Orange exchanges defective parts and accessories, its rims and hubs among them, for one year from the purchase date. Proof of purchase is required, because the warranty period runs from the day the part was bought.
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.
Chronos Boost Rear Hub questions
Will this fit a 142mm frame?
No. Boost 148 is wider. For 142mm or 135mm frames choose the Chronos Rear ISO 6 Bolt Disc Hub.
Which freehub body for SRAM Eagle?
SRAM XD. For Shimano 12-speed mountain choose Micro Spline.
Can I run it single-speed?
Yes, on the Shimano HG body with a single-speed cog and spacers. It is offered for single-speed mountain builds in our configurator.
Will my Centerlock rotor fit?
No. It is 6-bolt only, so use an ISO 6-bolt rotor.
Is the engagement fast enough for mountain biking?
36 teeth is fine for most trail and bikepacking riding. Velo Orange sells a 54-tooth ratchet for technical riding.
Is ProWheelBuilder the manufacturer of the Chronos Boost rear?
No. Velo Orange makes the hub. ProWheelBuilder is an independent custom wheel builder in Georgia that builds it into a 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.
