Trek Fuel EX 9.9 29 first ride review

Trek's latest trail bike is one to watch


Our review

The most capable incarnation of Trek's popular trail bike to date
Pros: Spirited handling; good suspension performance
Cons: Ultra low bottom bracket might not suit everyone; proprietary headset
Skip to view product specifications

Trek popped the top on the 27.5+ versions of the new Fuel EX in late May. Now Trek is ready to unveil the rest of the 2017 Fuel EX line. The latest Fuel EX is lower and slacker, with more travel than ever before.


Trek Fuel EX 9.9 29 highlights

  • 130mm front and rear travel
  • Adjustable geometry
  • 27.5+ compatible
  • Full OCLV carbon frame
  • 25lb/11.3kg weight (size 17.5)
  • Offered in five frame sizes
  • Available now

A harder-hitting trail bike

It appears Trek’s design team has been paying close attention to the desires of trail riders, many of whom have been gravitating toward short-travel 29ers with slack geometry, and redesigned the Fuel EX accordingly.

“We saw the direction trail bikes are heading — riders are getting much more aggressive and we wanted to make a bike that was very capable, but that could still be ridden all day,” said Trek’s mountain bike brand manager Travis Ott.

The previous iteration of Trek’s best-selling mountain bike featured 120mm of matched suspension travel. The new Fuel EX gets a bump in travel to 130mm at both ends. More noteworthy than the slight increase in suspension numbers is a significant overhaul of the bike’s geometry.

Like its predecessor, the latest generation uses Trek’s Mino Link to tune the suspension between a high and steeper setting or a lower and slacker position. In the low mode — which, by the way, is the position this tester has had most fun with — the Fuel EX sports a confidence-inspiring 67-degree head tube angle, a low bottom bracket height of 13.1in / 33.5cm, and chainstays that measure in at just 17in / 433mm.

The Fuel EX 9.9 29 uses Trek’s Mino Link to adjust the geometry between a high and low position – the Fuel EX will come with the geometry in the high mode: The Fuel EX 9.9 29 uses Trek’s Mino Link to adjust the geometry between a high and low position – the Fuel EX will come with the geometry in the high mode
Josh Patterson / Immediate Media

Where the previous Fuel EX felt much like a long-legged marathon XC machine, this incarnation is very much a wanton trail reaper. The new bike’s aggressive geometry is close enough to the much-lauded Remedy 29 that there would have been significant overlap between the two families. As a result, Trek will only offer the Remedy in a 27.5in versions for 2017.

Spirited and sporty handling

The Fuel EX 9.9 29 makes short work of rough trails, but not in the same manner as some longer-travel 29ers. It doesn’t numb terrain the way big wheels with more suspension travel are apt to do. Instead, it retains a playful, huck-happy demeanor. In the slackest mode, the 67-degree head angle is right on par for a bike of this breed. The short chainstays and low bottom bracket make this bike easy to carve though turns and responsive to quick changes in rider posture.

While pedal-scrapping bottom bracket heights are trending across the industry right now, they do require the rider to be more attentive to timing and positioning when pedaling though rough terrain. It’s certainly not a deal-breaker, but it is something to be mindful of.

The Fuel EX 9.9 29 has a Fox Float 34 suspension fork 130mm of travel : The Fuel EX 9.9 29 has a Fox Float 34 suspension fork 130mm of travel
Josh Patterson / Immediate Media

If, like me, you find you prefer the handling of the Fuel EX in the lower setting but need a bit more breathing room between the pedals and the mother earth, one possible solution is to mount a longer-travel fork in place of the stock 130mm model.

In addition to compatibility with longer forks, all the bikes of the Fuel EX 29 line are also compatible with 27.5+ wheels. The 27.5+ Fuel EX models unveiled earlier this summer share the same frame as the 29in Fuel EX 29. To preserve handling, Trek suggests replacing the stock 130mm fork with a 140mm version.

Don’t go overboard, however. A 140mm fork is the longest travel fork Trek recommends using with the Fuel EX platform.

Frame features

Trek’s catalog of mountain bike technologies are featured in the Fuel EX 9.9 29. The full OCLV carbon frame has internal routing through the down tube and relies on Trek’s ABP suspension system with the aforementioned Mino Link.

New for the Fuel EX is the ‘Knock Block’ headset and bumper system, which prevents the fork crown from impacting the down tube — a feature made necessary by the straight junction between the down tube and head tube. Trek claims this design bolsters front-end stiffness, albeit at the expense of fork clearance.

It’s refreshing to see that Trek still sees a need for chainguide tabs on trail bikes. While chain retention is much improved with clutch derailleurs and narrow-wide chainrings, it’s not perfect. The ability to run a bashguard is also a plus for bikes with low bottom brackets.

Initial equipment observations

As the top bike in the line, the Fuel EX 9.9 29 comes with a premium build to back up the high price tag.

Rear suspension is handled by Fox Factory Float shock with Trek’s RE:aktiv valving. The shock tune appears to have been firmed up from previous versions of this regressive damper, which was apt to blow through its travel when it encountered high-velocity impacts.

Trek’s RE:aktiv valving is incorporated into the Fox Float shock: Trek’s RE:aktiv valving is incorporated into the Fox Float shock
Josh Patterson / Immediate Media

While still early in the testing stages, it has proven to absorb square-edge impacts without diving too deeply into the stroke. Unlike the RE:aktiv shock on the Remedy 29 tested last year, there’s no need to add a volume reducer to firm things up.

Although the bike comes equipped with a 125mm dropper, most frame sizes could easily accommodate 150mm version. While we’re discussing droppers, Bontrager’s new Drop Line seatpost appears very well executed. It’s too early to discuss durability, but the action is smooth and the ergonomics of the 1x-specific under bar lever are spot-on. Look for a full Drop Line review in the coming months. 

Last but certainly not least on the list of standout components is SRAM’s Eagle X01 drivetrain. Even diehard 1x zealots have to admit there are situations where having a granny gear is advantageous and if a massive 50t cog doesn’t count as a bailout gear, I don’t know what does.

The Eagle XO1 drivetrain shifts smoothly : The Eagle XO1 drivetrain shifts smoothly
Josh Patterson / Immediate Media

This new 1×12 drivetrain offers a wide gear range that may get 1x naysayers onboard with single-ring drivetrains, provided they’re willing to stomach the cost.


Early verdict

While testing has just begun, the Fuel EX 9.9 29 is off to a promising start. Handling is good and the stock shock tune appears to be improved from past versions. Check back for a full review.

Product Specifications


Name Fuel EX 9.9 29
Brand Trek

Available Sizes 15.5in 17.5in 18.5in 19.5in 21.5in
Stem Bontrager Line Pro, 50mm, 35mm clamp
Rear Wheel DT Swiss XMC1200 Carbon
Front Wheel DT Swiss XMC1200 Carbon
Tyres Bontrager XR3 Team Issue, Tubeless Ready
Wheelbase (in) 45.5
Top Tube (in) 23.6
Standover Height (in) 29
Seat Tube (in) 16.5
Chainstays (in) 17
Bottom Bracket Height (in) 13.18
Weight (lb) 25
Chainring Size (No of Teeth) 32
Year 2017
Wheelset DT Swiss XMC1200 Carbon
Weight (kg) 11.3
Shifters SRAM Eagle XO1
Bottom Bracket PF92
Frame Material OCLV carbon
Brakes SRAM Guide, 180mm front rotor, 160mm rear rotor
Cassette SRAM Eagle XO1, 10-50t
Chain SRAM Eagle
Cranks SRAM Eagle XO1
Fork Fox Factory 34 Float, FIT4 damper, 130mm travel
Fork Offset 51
Front Derailleur N/A
Seatpost Bontrager Drop Line 125, 31.6mm
Grips/Tape Bontrager Race Lite, lock-on
Handlebar Bontrager Line Pro, OCLV Carbon, 35mm clamp, 15mm rise, 750mm width
Headset Type Trek Knock Block
Rear Derailleur SRAM Eagle XO1
Rear Shock Fox Factory Float EVOL, RE:aktiv
Saddle Bontrager Evoke RXL, carbon rails
Frame size tested 17.5in