The Go-Anywhere Fat Tyre Bike for Every Terrain and Every Season

The Trek Farley 5 is a fat bike built around the premise that no terrain should be off-limits. The 27.5-inch fat wheel format with 4.5-inch wide tyres provides float over snow and sand, traction on mud and loose dirt, and the stability that comes from a large contact patch on surfaces where narrower tyres would sink or slip. The combination of wheel diameter and tyre width delivers a specific riding character - slow-speed stability and grip rather than outright rolling speed - that makes the Farley 5 genuinely capable in conditions that no other bike type handles as well.

The frame is built from low-emission aluminium - part of Trek's manufacturing transition that began in 2024, completed for this model by October 2025 - producing a frame with a significantly lower manufacturing carbon footprint than standard aluminium production. Internal routing throughout the frame protects components from the elements and makes it easier to attach gear-carrying accessories without cables and housing interfering with the setup. Mounts cover the frame for wide-ranging gear-carrying customisation, allowing the Farley 5 to be configured for day rides, multi-day bikepacking, or loaded expedition riding without requiring dedicated luggage-specific frames.

The internally routed dropper post allows the saddle to be lowered for steep descents, moving the rider's weight back and lowering the centre of gravity on technical downhill sections - a feature that makes a meaningful difference on steep fat bike terrain where the combination of large tyre footprint and lower saddle creates a significantly more controlled descending experience.

• All the mounts make it easy to add accessories and customize Farley for how you want to roam
• It comes with a carbon fork that has lower leg mounts for gear cages, mounts for our custom front rack, and rubber bumpers to protect the dropouts when the front wheel is removed
• Its huge 4.5-inch tires will keep you floating over snow, sand, mud, and dirt
• The progressive trail geometry feels more capable and confident than ever
• The internally routed dropper post lets you move around on the bike and get behind the saddle on steep descents

OCLV Carbon Fork with Adventure Mounts and Protective Bumpers

The Farley 5's OCLV carbon fork is a purpose-built adventure component rather than a standard lightweight fork adapted for fat bike use. A short offset places the rider in an optimal position over the front wheel, improving traction on sketchy terrain and allowing the use of a shorter stem for more direct steering feel. A custom rack mount on the fork crown accepts a compatible front rack, and triple bottle bosses at 64mm spacing on the lower legs accommodate gear cages for additional carrying capacity on either side of the front wheel.

Rubber bumpers are fitted to the bottom of the fork legs - a practical detail that protects the dropouts and keeps the bike standing upright when the front wheel is removed for vehicle transport or storage. On a fat bike where wheel removal is a regular occurrence for vehicle loading or flight transport, this protection prevents the fork from being damaged by contact with the ground during the process.

Haul of the wild

Mounts all over the frame let you carry a wide variety of gear with endless customization options. Gummy bears? Extra layers? Camping gear? Haul it all.

Keep it clean

Internal routing helps to protect Farley's components from the elements and makes it easy to mount gear

Rapid Drive 108 Rear Hub and Progressive Trail Geometry

The Rapid Drive 108 rear hub provides 108 points of engagement - approximately one engagement point every 3.3 degrees of rotation. This high engagement count means the hub begins transferring pedalling force to the rear wheel almost immediately when the rider steps on the pedals, rather than the longer lag that lower engagement-count hubs produce before the pawls fully engage. On a fat bike used in varied terrain where short acceleration bursts out of corners and on steep technical sections require immediate power delivery, the near-instant engagement of the Rapid Drive 108 provides a noticeably more responsive pedalling feel.

The progressive trail geometry updates to the Farley include a slacker head tube angle for improved stability and confidence on technical terrain, and a steeper seat tube angle that improves pedalling efficiency and provides a more comfortable reach to the handlebars. These geometry changes reflect the direction of modern trail and enduro bike design applied to the fat bike platform, making the Farley 5 feel more capable and controlled than older fat bike geometries that were optimised primarily for flotation rather than handling dynamics.

A better way to produce aluminum

Starting in 2024, we began removing high-emission aluminum from our manufacturing and replacing it with low-emission aluminum made with renewable energy. By October 2025, nearly every alloy bike we make - this one included - had made the switch, driving a major drop in our footprint.

FAQs

What tyre size does the Trek Farley 5 use?

The Farley 5 uses 27.5-inch fat wheels with 4.5-inch wide tyres, providing float over snow, sand, and mud while maintaining the rollover capability of the 27.5-inch wheel diameter.

What fork does the Farley 5 come with?

The bike is fitted with an OCLV carbon fork with a short offset, a custom rack mount on the crown, triple bottle boss mounts on the lower legs, and rubber bumpers to protect the fork when the front wheel is removed.

Does the Farley 5 have a dropper post?

Yes. The Farley 5 includes an internally routed dropper post, allowing the saddle to be lowered for descents without external cable routing.

What is the Rapid Drive 108 rear hub?

The Rapid Drive 108 hub uses 108 points of engagement, providing nearly instant power delivery when pedalling is resumed after coasting, for more responsive acceleration out of corners and on technical terrain.

What mounts are available on the Farley 5 for gear carrying?

The frame and fork include mounts throughout for gear cages, racks, and accessories. The fork has a custom rack mount at the crown and triple bottle bosses at 64mm spacing on the lower legs. Frame mounts allow wide-ranging customisation for bikepacking and loaded riding.

What geometry changes have been made to the Farley 5?

The Farley 5 features a slacker head tube angle for improved stability on technical terrain and a steeper seat tube angle for better pedalling efficiency and comfortable reach.

What is the low-emission aluminium used in the Farley 5?

From 2024, Trek transitioned its alloy manufacturing to aluminium produced using renewable energy. By October 2025 the Farley 5 had completed this switch, reducing the frame's manufacturing carbon footprint significantly.

Specs:

Geometry Chart