First Impression: Trek Fuel EX 29 9.9

Few bikes have such a storied lineage as the Fuel EX. Trek introduced a refreshed version of its 27.5-wheeled version last year with the incorporation of the Fox Re:aktiv shock technology. This year the 29er model gets the same treatment, with a host of the same features plus some new ones.


While still built around a 120 mm travel, full-floating, ABP (active breaking pivot) suspension design, the new Re:aktiv shock was designed with input from auto racing powerhouse Penske Racing shocks, a company that is normally designing products for Formula 1 cars. The idea is that it can detect the difference between different inputs (pedaling forces versus impacting a root at speed) and adjust on the fly. The speed that the shaft moves is what dictates how the damping reacts. It’s a rather complex technology that is found on only some of the top models, starting with the Fuel EX 8.


Unique to the 29er model is the introduction of Boost spacing front and rear. The 12×148 mm thru axle out back and 15×110 mm on the fork push the hubs’ flange spacing out and allow for a stronger, stiffer wheel. Trek says it makes the 29er wheel as stiff as a 27.5 wheel, and while I can’t say I can tell a major difference in the DT Swiss wheels, I have no reason to doubt their claims.


The 9.9 build we’re riding is the flagship model in the new Fuel EX range, with a full OCLV carbon frame, chainstays, seatstays and rocker link. Geometry is adjustable with the small Mino Link, an eccentric pivot where the seatstays meet the rocker link that alters the head tube angle, bottom bracket height and chainstay length a small amount.


Some key geometry numbers in the Low and High settings:

  • Head tube angle: 68.8 / 69.4 degrees
  • Effective seat tube angle: 73.6 / 74.6 degrees
  • Chainstay length: 436 / 434 mm
  • Bottom bracket height: 13.15 / 13.46 inches

trek-fuel-ex-29-first-impression-14 trek-fuel-ex-29-first-impression-4

The frame also features internal cable routing that integrates nicely with the Control Freak ports. There are also attachments to run the rear brake cable externally, if that’s more your style.


Hanging on is a 120 mm Fox 34 fork with the new and drastically improved FIT4 damper, a 1×11 Shimano XTR kit powered through a carbon Race Face Next crank. The RockShox Reverb Stealth sits up top and the carbon DT Swiss XMC1200 wheels put the power to the ground.

This is a spare-no-expense build ($8,400 to be specific) but Trek knows us media slimeballs are hard to please. (OK, that’s not the reason at all, actually. Brands want to show off the best of what they can do and what their employees work so hard to create, something I can hardly blame them for.) I’ll admit it is a little intimidating knowing that it retails for twice what I paid for my pickup truck.


My first ride on the Fuel EX 29 9.9 was on some dedicated gravity trails where it felt right at home. The only thing holding it back was the 720 mm carbon Bontrager handlebar the stock Bontrager XR3 front tire, which was begging for something more aggressive. (Update: Trek informed me that some early bikes shipped with a 720 mm bar, while the stock bikes ship with a 750 mm Bontrager Rhythm Pro bar.) You’ll see in the photos I swapped in a 750 mm Truvativ Jerome Clementz BlackBox handlebar cut specifically for the new WTB Padloc grips, which I’m also testing. Plus a bell. Ding!


I also had a packaging issue with the Reverb remote conflicting with the XTR Trail brake, leaving it skewed at a less-than awesome angle. Usually it’s mounted below the bars on the left side, but this bike shipped with the right/bottom, left/top remote.


Aside from a few spec hiccups, the Fuel EX has really impressed me with its ability as an all-around performer. This is a bike I wouldn’t hesitate to line up for an XC race or toss on a chairlift for some bike park runs. I have very high expectations for this bike and have no doubt it has the ability to reach or exceed them. I’m looking forward to our time together! Keep an eye out for my full-length review in an upcoming issue of Dirt Rag.

Update: Some folks have asked about converting the Fuel EX 29 to 27plus. While a 27×3.0 tire easily fits in the Boost-spaced fork, it rubs on the chainstays on the frame. A few tweaks to the rear end might make it possible, so will we see something like that in the future? We’ll have to wait and see. Trek has been committed to the 29plus platform, so a whole new bike is just as likely.