Trek Bikes Fuel EX 9.8 27.5  2015 Mountain Bike Review

Trek Bikes Fuel EX 9.8 27.5 2015

Reviews / Trail Bikes

Trek Bikes 1,642,047

At A Glance

We were lucky enough to have a first ride on this bike when it was launched in the US about 10 months ago. We loved it then and after spending a lot more time on it over the last couple of months we love it even more.

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The Fuel EX has been the pinnacle of the Trek trail bike range for a few years, it has seen some upgrades and changes in that time but there is a multitude of fans that love this bike the world over. For 2015 it gets some serious upgrades, there is a return to the 120mm of travel front and rear from a few years ago, but this is backed up with 27.5” wheels and the all new RE:aktiv suspension set-up that Trek have been working on with Penske Racing in the US.

Think Formula 1 style reactive suspension and you’re on the right track!

On The Trail

After our brief flirt with the EX in the US it was great to put some miles on her and find out how she rode over more varied and challenging terrain. As it turned out the bike was just as ridiculously playful and fun to ride on our local trails as it was in North Carolina; it hammers into the corners and spits itself out the other side with a speed that almost takes you by surprise.

At the heart of this bike is the new shock, and it really is rather special, if you haven’t ridden a bike with RE:aktiv yet, take it from us, it’s impressive stuff. The new shock just offers so much more feedback in terms of the trail and it sits up in its travel offering unparalleled pedalling performance. Yet when you point the bike downhill the whole feel of the bike changes without you doing anything.

The shock comes with CTD as standard and in the Climb mode you get a very useable lock-out setting that still offers some travel should and when you need it. If you forget to flip the switch when going down instead of having a stiff uncomfortable ride you can actually get away with the mistake all the way to the bottom, or until such time you want to take a hand off the bar and flip the switch.

In the Trail mode however, the bike really comes into its own. The shock offers superb pedalling efficiency with minimal movement, and then comes alive when the trail flattens off or steepens. The bike feels noticeably livelier and more playful, I found myself whipping it around with this stupid grin on my face thinking that this all makes total sense. No batteries or electrics, just a shock and damping system that is capable of knowing what the terrain is doing.

In the Descend mode the shock is opened up, so the damper isn’t doing much, on big rough descents this makes for a comfortable ride, but on flatter terrain the bike feels sluggish as the RE:aktiv damper isn’t engaged.

Over the couple of months I found I mostly just left the bike in Trail mode, no matter where or what I rode, it’s so capable and with the damper working at full capacity this bike can handle pretty much anything your throw at it.

With the light carbon frame and high-end component set you get a very nimble bike indeed. Long climbs are quickly dispensed with and technical sections are handled with aplomb. On the more exciting terrain the bike has speed that is easily conjured and confidence-inspiring geometry that will have you pushing faster and harder than before.

There are a couple of areas where this bike could be improved, the 32mm stanchion fork doesn’t feel as stiff as the 34mm forks we have become used to. With the capable geometry you’ll be hunting out the rougher stuff and at speed it lacks just a little.

The XT drivetrain is perfectly functional, but as this is a 9.8, just one off the top spec it does feel a little under specced. Those are two small quibbles rather than complaints and for the vast majority of riders looking at a 120mm travel trail bike this won’t be an issue. Over the course of the test we had no issues with the drive train, but we couldn’t help but feel a little underwhelmed by the badging when the rest of the bike is so highly specced out.

With that being said though, the Fuel EX is simply a joy to ride on any given trail, there is so much energy won back from the bike and the trail it almost feels like cheating.

Tech Heads

The frame is an OCLV Mountain Carbon front triangle and seat stay with an alloy chainstay. Full carbon armour and all of Trek’s tech has been added including the Active Braking Pivot Convert set up, Full Floater, E2 Tapered Head tube, BB95, internal derailleur & dropper post routing, ISCG 05 mount, magnesium EVO link, 120mm travel.

Suspension is looked after by Fox, with a Factory Series 32 Float CTD FIT Damper Kashima Coat 15mm QR and 120mm of travel. The rear is the jewel in the crown we have talked so much about, it is built around a Factory Series Float DRCV with the RE:aktiv damper and CTD with Kashima Coat and tuned by Trek in California.

The drive train is a full Shimano XT affair with a 38/24 crankset and 11-36 10-speed cassette. Braking duties are again looked after by Shimano with XT hydraulic discs 180mm rotor on the front and a 160mm rotor on the rear.

The cockpit and finishing kit is mostly Bontrager as you would expect. A Bonty Evoke 2 saddle is held up on the excellent Rock Shox Reverb dropper post. Bontrager Race X Lite carbon bars are held in place by a Race X Lite stem.

Bontrager Rhythm Comp Tubeless Ready wheels come equipped with TLR strips, Stacked Lacing, 142x12 rear hub and 15mm front hub. These are shod with Bontrager XR3 Expert, Tubeless Ready, aramid bead, 27.5x2.35" front, 27.5x2.20" rear

Trek Fuel EX 9.8 27.5 Medium

Seat tube 445mm
Effective top tube 608mm
Head tube 110mm
Chain stay 433mm
Wheel base 1155mm
BB Drop -17mm
Head angle 68°
Seat angle 73°

Weight w/o pedals 27.5lbs


Light, fast and nimble the lower longer and slacker geometry of the Fuel EX is confidence-inspiring to say the least. The RE:aktiv shock is simply sublime and offers really great advantages to the way the bike handles.


Whilst this bike comes in at a reasonable price, and is a 120mm trail bike, the 32mm stanchion fork could be a bit stiffer and the drivetrain could be better.


If you are in the market for a capable trail bike that is brimming with the latest tech, but doesn’t require its batteries to be recharged then take the Fuel EX for a spin. Be warned though, once you fall in love with the RE:aktiv shock and the way this bike rides you’ll be reaching for your credit card!

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This review was in Issue 35 of IMB.

For more information visit Trek Bikes


By Rou Chater
Rou Chater is the Publishing Editor of IMB Magazine; he’s a jack-of-all-trades and master of none, but his passion for bikes knows no bounds. His first mountain bike was a Trek 820, which he bought in 1990. It didn’t take him long to earn himself a trip to the hospital on it, and he’s never looked back since. These days he’s keeping it rubber side down, riding locally and overseas as much as possible.

Tried this? What did you think?