Fox 40 15mm Adapter

Why doesn’t your 15mm Boost wheel fit your Fox 40? Most modern trail bikes, enduro bikes and e-bikes use a 15×110 Boost front hub, while the Fox 40 uses a larger downhill axle system. Even when the hub width is 110mm, the axle diameter and fork interface are different. That is why your 15×110 Boost wheel cannot simply be installed in your Fox 40.
The Freakynuts® Fox 40 15mm Adapter solves exactly that problem. It allows you to use a compatible 15×110 Boost front wheel in your Fox 40 without buying another complete front wheel. One wheel. More bikes. Less hassle.

Use Your Existing 15×110 Boost Wheel

A second downhill front wheel quickly becomes expensive. You need another rim, hub, brake rotor, tyre, tubeless setup and possibly another tyre insert. If you already own a wheel that you like, why build another one just because your Fox 40 uses a different axle system?
The Freakynuts® adapter creates the correct interface between your 15×110 Boost wheel and your Fox 40. No permanent modification to your fork. No permanent modification to your wheel. Just a purpose-built adapter system.

CNC Machined in Germany

Every Freakynuts® adapter is CNC machined in Germany from premium 7075 aluminium. The front axle area of a downhill bike has to deal with serious braking forces, impacts and repeated loads, so material quality and accurate manufacturing matter.
7075 aluminium offers high strength, excellent stiffness and very good fatigue resistance without unnecessary weight. Every component is machined to precise tolerances so the wheel sits exactly where it belongs.

Precision Instead of a Loose Sleeve

A downhill adapter should do more than simply reduce a 20mm axle interface to 15mm. The wheel must be positioned accurately inside the fork and supported correctly by the complete axle system.
That is why Freakynuts® adapters are designed as a complete mechanical solution. The result is a precise fit, secure axle support and consistent wheel positioning.

No Saw Cuts. No Fork Modifications.

We do not believe an expensive downhill fork should be drilled, cut or permanently modified just to use another front wheel.
The Freakynuts® system is designed to work without irreversible modifications to your Fox 40. Your wheel remains a normal compatible 15×110 Boost wheel, so you can still use it in another Boost fork when required.

Basic, Pro or Premium

The Basic Adapter is ideal if you already have a suitable extra-long 15mm thru axle.
The Pro Kit combines the precision adapters with our KingPin solid 7075 thru axle for a complete Freakynuts® setup.
The Premium Kit is our flagship solution, combining the adapter and axle concept into a more integrated system with fewer separate parts.
Choose the version that fits your bike and riding style.

Older Fox 40? Check the Brake Position

Some older Fox 40 models use the classic non-Boost brake mount position. This can create another problem when you try to install a modern 15×110 Boost wheel.
If the wheel fits between the fork legs but the brake rotor touches or scrapes against the brake mount, the axle diameter is not the only issue. The brake disc sits in a different position on a Boost hub compared with the older non-Boost downhill standard.
That is exactly why we developed the Freakynuts® Boost / Non-Boost Converter.
The converter corrects the brake-side position and makes it possible to use a compatible 15×110 Boost wheel in older Fox 40 models with the classic non-Boost brake mount position.
So if your 15mm Boost wheel physically fits but your brake disc hits the fork or brake mount, you know what you need: the Freakynuts® Boost / Non-Boost Converter.

Built for Downhill and Freeride

The Fox 40 is made for downhill racing, bike parks and aggressive gravity riding. That is exactly the environment the Freakynuts® system was developed for.
Use the front wheel you already know. Use the tyre setup you already trust. Ride your Fox 40 without building another complete wheel.
Freakynuts® Fox 40 15mm Adapter. Ride your 15×110 Boost wheels everywhere.