Industry Nine Hydra 2 MTB Front ISO 6 Bolt Disc Hub
Industry Nine machines and anodises it in Asheville, North Carolina, in every color it makes. This page covers the Industry Nine Hydra 2 MTB Front ISO 6 Bolt Disc Hub.
The Hydra 2 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
The Hydra 2 keeps that and makes the parts around it bigger.
The hubshell is machined from aluminum bar with J-bend flanges in 28 and 32 hole, anodized in Industry Nine's full color range, with centerlock or 6-bolt rotor mounts and end caps for Boost, Superboost and standard spacing.
This is the front hub, and a front hub has no freehub. What matters here is the part of the hub that carries the wheel: the bearings, the seals, the axle and the two flanges, and the front Hydra 2 shares all of them with its rear partner. It is the simpler half of the pair and the one that runs longest between services. The driver and engagement story belongs on the rear hub's page; this page is about a front wheel that spins freely, stays sealed and builds stiff.
How it rides
We build the Hydra 2 for trail, enduro, downhill and e-bike wheels; the thicker axle and bigger bearings make it a better e-MTB hub than the original.
Front wheels on disc bikes take a beating from braking: the rotor side sees the whole braking torque and the spokes on that side run at higher tension. That is why we build the front Hydra 2 with the rotor-side spokes crossed and tensioned to the rim's limit, and why the hub's flange spacing matters more than its weight. Ridden on a rim-brake bike the same hub makes one of the lightest, simplest front wheels there is.
Specifications
| Position | Front |
|---|---|
| Axle options | Thru Axle 15x110mm Boost Front, Thru Axle 15x110mm Boost Front With Torque Caps, Thru Axle 20x110mm Boost Front |
| Drillings | 32h |
| Spoke head | J-bend |
| Brake | 6-bolt disc |
| Left flange diameter | 59.5 mm |
| Right flange diameter | 46 mm |
| Left center-to-flange | 28 mm |
| Right center-to-flange | 41 mm |
| Spoke hole diameter | 2.6 mm |
| Weight | 157g |
| Material | Aluminum |
| Finishes | black, blue, bronze, gold, green, lime green, orange, pink, purple, red, silver, turquoise |
This version
This version is the 6-bolt hub in Thru Axle 15x110mm Boost, Thru Axle 15x110mm Boost With Torque Caps, Thru Axle 20x110mm Boost, drilled for 32h, about 157g, in black, blue, bronze, gold, green, lime green, orange, pink, . Those are the only things that differ between the versions of the Hydra 2; 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
J-bend spokes in any gauge; we build most Hydra 2 wheels with Sapim Race, D-Light or CX-Sprint spokes or DT Competition and brass nipples, and Industry Nine also sells a straight-pull version for its own alloy spokes.
It pairs naturally with Industry Nine's own Grade 300, Triad and Sector rims, and with Reserve, ENVE, We Are One, Nox, DT Swiss, Race Face and Stan's rims that match its drilling. The configurator recommends spoke count and lacing from your bike type and weight.
Build a wheel around it
Offered for mountain bike, MTB single-speed, fat bike and tandem and e-bike builds in our Custom Wheel Program. Start with the Industry 9 Hydra 2 MTB Front ISO 6 Bolt Disc Hub and the configurator pins it for you, then checks each choice you make against it.
How Industry Nine tests its hubs
Industry Nine states it "has been anodizing & machining hubs, spokes, and drive systems in Asheville, NC since 2004" and that it engineers and manufactures every component of its hub and wheel systems in-house, including hub shells, axles, spokes and anodizing: "If it moves inside an I9 hub, we made it." Coverage of the Hydra2 launch (March 2025) reports Industry Nine drew on data from over 100,000 Hydra hubs in use to redesign the hub, with a 65% thicker axle "engineered for superior stress dissipation", larger 6903 bearings throughout, a labyrinth channel and full-contact radial lip seals against contamination. Industry Nine publishes no bearing-cycle, salt-spray, ISO 4210 or laboratory test figures for its hubs.
Warranty: Industry Nine states "Hubs are covered for five years against defects in materials and workmanship." Years 0-2 include parts, labor and return shipping; in years 3-5 parts are covered and labor and shipping may apply. Warranties apply to the original purchaser only with proof of purchase from a certified dealer; bearings and other normal wear items are excluded. Industry Nine says service needs only basic tools, "no proprietary tools are required".
Certifications
- Made in USA (Asheville, NC) — Industry Nine states hubs, spokes and drive systems have been anodized and machined in Asheville, NC since 2004; site tagline "HANDBUILT - ASHEVILLE, NC - KAMLOOPS, BC" (source)
- 5-year hub warranty — Parts, labor and return shipping years 0-2; parts only years 3-5; original purchaser; bearings excluded (source)
Sources on Industry Nine's site:
- About Industry Nine
- Industry Nine Warranty
- Industry Nine Hydra 2 Hubs (product page)
- Industry Nine Support Documents
- Industry Nine Hydra2 Support
The figures, certificates and media above are Industry Nine's own. ProWheelBuilder does not run these tests; our part is the wheel we build on the hub.
Building it at ProWheelBuilder
Industry Nine makes the Hydra 2 in Asheville, North Carolina; 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
Industry Nine's warranty. Industry Nine covers its hubs against defects in materials and workmanship for five years from purchase, with two years on the anodized finish. Its alloy and carbon rims carry a lifetime defect warranty to the original purchaser, with parts, labor and return shipping covered for the first two years and parts thereafter. Bearing wear, impact and crash damage are not defects.
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.
Hydra 2 MTB Front 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.
Is the Hydra 2 e-bike rated?
Yes. The thicker axle and larger bearings were designed with e-MTB loads in mind; tell the configurator it is an e-bike and it picks the spokes.
Is ProWheelBuilder the manufacturer of the Industry Nine Hydra 2 MTB Front ISO 6 Bolt Disc Hub?
No. Industry Nine makes the hub. ProWheelBuilder is an independent custom wheel builder in Georgia that builds it into a finished wheel to your spec.
Does it need special spokes?
No. It takes standard J-bend spokes, which the configurator offers in every gauge and finish we stock.
How long will the wheel take?
Build time comes down to parts availability rather than bench time. The estimated ship date is shown in the configurator before you check out.
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.
