Trek's Farley 9.8 is like whipped chocolate - big and fat but still light and fluffy

Massive tyre clearance but with a narrow Q-factor and ultra-low weight

Trek’s Farley range of fat bikes has always taken a different tack with slightly smaller-than-typical tyres that work reasonably well on snow but are more versatile everywhere else. The new upper-end carbon fibre Farley models take that philosophy even further with larger-diameter 27.5x3.8in tyres that supposedly offer the same benefits that bigger wheels do for trail bikes – but still with plenty of clearance for the fattest 26in wheels and tyres when the snow starts to fall.

Building a frame to handle both of those wheel and formats is relatively easy in one sense, since the overall diameters are so similar. However, accommodating that massive 5in width required a bit of ingenuity. 

Aluminum Farleys use 177mm-wide rear dropout spacing and a 100mm-wide threaded bottom bracket – both dimensions being on the narrower end of things as far as fat bikes are concerned – and just barely accommodate 26x4in tyres. The new carbon Farleys, however, can gobble up tyres as wide as 26x5in but still maintain the same pedal stance width and chainstay length.

The widened rear end can now accept a 26x5.0in tire but yet pedal stance width remains the same as the old bike, which could barely take a 4.0in one: the widened rear end can now accept a 26x5.0in tire but yet pedal stance width remains the same as the old bike, which could barely take a 4.0in one
The widened rear end can now accept a 26x5.0in tire but yet pedal stance width remains the same as the old bike, which could barely take a 4.0in one: the widened rear end can now accept a 26x5.0in tire but yet pedal stance width remains the same as the old bike, which could barely take a 4.0in one

It took some doing to build the carbon Farley to accept the biggest 26in tyres on the market but without increasing pedal stance width or chainstay length

As expected, rear hub spacing on the new carbon bikes move to the wider 197mm thru-axle format – essentially the standard for fat bikes running such wide tyres. Instead of widening the bottom bracket shell by 20mm to compensate, though, Trek has moved to a 122mm press-fit format that keeps the bearings and cranks in the same positions as before but still allows the impossibly thin chainstays (just 13mm thick each!) to be pushed further apart for more clearance. To maintain a proper chainline, the direct-mount chainring is flipped from its usual orientation so that it’s offset to the outside.

Even more impressive is how Trek retained the current Farley’s tight 440mm chainstay length while still gaining all that newfound tyre clearance. Should you desire a little more stability (or even want to run a singlespeed drivetrain), sliding ‘Stranglehold’ dropouts let you extend the rear end out another 20mm.

The 122mm-wide press-fit bottom bracket yields the same pedal stance width as a 100mm-wide threaded shell: the 122mm-wide press-fit bottom bracket yields the same pedal stance width as a 100mm-wide threaded shell
The 122mm-wide press-fit bottom bracket yields the same pedal stance width as a 100mm-wide threaded shell: the 122mm-wide press-fit bottom bracket yields the same pedal stance width as a 100mm-wide threaded shell

Key to the bike's design is the 122mm-wide press-fit bottom bracket shell

Claimed frame weight is 1.3kg (2.93lb) – barely heavier than many traditional hardtails – plus 550g for the matching rigid carbon fork.

Our flagship Farley 9.8 comes dressed to the nines with a wealth of top-shelf kit and nearly every major component crafted from carbon fibre – as it should given the $4800 / £3500 / €4700 price tag. Highlights include Bontrager Wampa tubeless-ready carbon fibre rims, a Bontrager carbon seatpost and handlebar, a Race Face Next SL carbon crankset, a SRAM X1/ XO1 1x11 transmission, SRAM Guide RS hydraulic disc brakes, and Bontrager Hodag tubeless-ready tyres.

Actual weight for the complete bike is a fantastically low 10.82kg (23.84lb, 17.5in size, without pedals or accessories).

The race face next sl carbon crankset is ultralight and yet remarkably durable: the race face next sl carbon crankset is ultralight and yet remarkably durable
The race face next sl carbon crankset is ultralight and yet remarkably durable: the race face next sl carbon crankset is ultralight and yet remarkably durable

There's absolutely no shortage of bling on the Farley 9.8

As impressive as the Farley 9.8 is on the scale, Trek made some compromises on the Farley 9.8 to hit that number as two key items are conspicuously absent: a suspension fork and a dropper seatpost. Neither is entirely necessary for winter riding, of course, but both would certainly add to the all-seasons versatility that the Farley is aiming for. Although neither item is included, the fork length and front hub spacing would make for an easy retrofit, and routing is including for a Stealth-style dropper if you want to add one.

Now if you’ll excuse us, it’s time to go ride…

For more information, visit www.trekbikes.com.

James Huang

Former Technical Editor, US
James was BikeRadar's US tech editor from 2007-2015.
  • Discipline: Mountain, road, cyclocross
  • Preferred Terrain: Up in the Colorado high-country where the singletrack is still single, the dirt is still brown, and the aspens are in full bloom. Also, those perfect stretches of pavement where the road snakes across the mountainside like an artist's paintbrush.
  • Beer of Choice: Mexican Coke
  • Location: Boulder, CO, USA

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