Trek Fuel EX 9.8 27.5

In 2014, when Trek turned their Fuel EX range into a 29er-only   platform, I was a very sad boy. It’s not that the 29ers were a bad bike, but the outgoing 26-inch wheeled Fuel EX had been a favourite of mine  for quite some time. It offered a perfect mix of efficiency and playfulness which, in my eyes at least, had made it one of the most versatile, capable and fun trail bikes of the last five years.  

You can no doubt imagine, then, that my interest was well and truly piqued by the emergence of the all new 27.5 wheeled version. It was with a mix of excitement and apprehension that I took delivery of the   carbon framed EX 9.8 for a few months of trouncing around on the trails. Excitement, because I hoped that the DNA of its predecessor would shine through in this new generation; and apprehension because the bar had been set pretty high and the new EX had a great deal to live up to.  

The lime green machine has been put through its paces on everything from smooth fire road grinds to chunky, natural downhill trails and the verdict is in; there’s a lot to like, and Trek have done a lot more than just slap some slightly bigger wheels onto the previous Fuel EX.  

FUEL ECONOMY  

The EX 9.8 is the second from top in a five bike line-up ranging in price from $9,999 down to $2,799. Their top model has a full carbon fibre frame, whilst the lower three are all alloy.  

With a carbon fibre frame and alloy chainstay, the $5,899 the Fuel EX 9.8 splits the difference between the exotic and the affordable. It features clean, classy and mostly straight lines with colour-matched   components and geometric decals that add a touch of mature sophistication to the aesthetics. The vibrant green isn’t as eye-watering as some of the fluoro colours kicking around at the moment, and whilst it still won’t be everyone’s cup of tea, it’s unlikely to date too quickly.  

There’s the now expected plastic down tube protector to guard against errant rock strikes, and the inclusion of ISCG tabs makes fitting a chain guide a breeze if you want to boost drivetrain security. Trek was one of the pioneers of carbon fibre bike construction and they’ve now been at it for two decades. From the massive, slightly angular tube shapes to the keyed pivot hardware, their experience and attention to detail is very clear; they’ve even bolted the front derailleur mount onto the seat  tube so it can be removed for a cleaner appearance should you wish to run a one-by transmission. 

It’s also good to see enough clearance around the rear triangle for rubber up to 2.4-inches wide. The 2,410g frame weight (19.5-inch) is definitely at the lighter end of the spectrum, especially given how burly and stiff the frame is, whilst the overall weight of 12.37kg without pedals reflects the inclusion of a dropper post, moderate  weight wheels and the two-by drivetrain  components. 

Shimano’s XT drivetrain and brakes  are what many ‘in the know’ riders would choose for a ground-up build. They offer a nice balance of bling and value for money along with a reputation for near  maintenance free serviceability that’s  second to none. The double front chainring goes against the current trend for one-by drivetrains, but it does mean you’ve got a gear for just about any terrain imaginable, whether uphill or down. 

Cable routing is a mixed bag; the rear  brake line is external (yay!) and whilst both derailleur cables are internal from the  factory, there is provision to run the front derailleur cable externally if you prefer,  although there’s no such option for the rear derailleur. The dropper post routing is  internal too, thanks to the highly regarded  RockShox Reverb Stealth. 

Bontrager (Trek’s in-house brand) provides the wheels, tyres and cockpit; all are  good value, high quality items. It’s great to see a nicely short 60mm stem, and whilst  the 720mm handlebar may be a tad narrow  for some by modern standards, it’s not far  from the mark; I fitted a 740mm wide alternative  after a few spins on the stock bar, but this will largely come down to personal  preference. 

In keeping with the current trend towards  longer front centre measurements, the 19.5-inch frame has a reach of nearly 450mm. This combines with the moderate 73-degree seat angle to create a 627mm  effective top tube; plenty long enough to stretch out on extended climbs and it’ll   help to keep your weight behind the front   wheel on nasty downhills too. Fortunately, Trek has also kept the chainstays respectably short at 433mm, so it’s easy to loft the   front wheel over drops and leaning back makes it easy manual your way down the street to impress a potential suitor. While the overall wheelbase is comfortably long, isn’t like steering a container ship.  

The Fuel EX’s bottom bracket height strikes a good balance between low for   carving turns, and high for pedal clearance on the ups; in my opinion too many manufacturers are, at present, forgetting that you need to get to the top of the hill before you can bomb back down, and technical climbing should be a strong point for mid-travel   bikes.  

Props also to Trek for continuing to make five frame sizes; with a medium, medium/large, and large, the vast majority of riders can get the perfect size rather than falling in between a too small and a too   big option. The geometry element I’m not sure about is the head angle; it’s stated as 68-degrees which is pretty normal, but on my first ride it felt steeper than that, so I had another look at the charts.

  

According to the Trek website, the geometry isn’t measured at the static height. Instead it’s taken with 25% sag at the rear suspension and only 10% at the front. I’d generally run a minimum of 15% at   the front and often 20% sag to improve traction. With more front sag head angle is more like 68.5-69 degrees. Whilst this is perfectly fine for climbing, traversing, and flow trails, it definitely feels less comfortable than some of the competition on rough   descents.  

RE:AKTIV REVOLUTIONS  

One big change for 2015 is in the EX   9.8’s suspension. It’s not a structural change; the ABP Full Floater suspension design is still there, as is Trek’s proprietary dual-chamber DRCV shock. These are very good things; I’ve always been a fan of the ABP design with its concentric rear axle pivot and active braking qualities. When   combined with the variable spring rate of the shock, it produces a rear end that is supple enough to hug the ground, yet supportive enough to pedal efficiently and resist blowing through the travel at the first sign of a ripple in the trail. What is new is the custom valved ‘RE:aktiv’ damper, developed as a collaboration between Trek, Fox  and motorsport suspension gurus Penske Racing.   

One of the biggest challenges in mountain bike suspension has always been to  have a design that doesn’t move excessively from rider weight shifts, braking  and pedalling input, but still reacts quickly  and easily to lumps, bumps and dips in the  trails surface—something that moves when  you want it to and remains stable at other  times. It’s not dissimilar in motorsport; a  Formula One car needs to be stable under  massive acceleration and braking forces  whilst still allowing the wheels to maintain ground contact over the ripple strips when  cornering. 

Lots of different ideas have been used to  try and balance these two conflicting needs; in the F1 world computers were used (until  they were banned), and in the MTB arena  we see technology like Fox’s CTD damper  and the Specialized ‘Brain’, which uses a  brass-weighted inertia valve to distinguish  between bump forces and rider movement. Critics often say that inertia valves produce a wooden on/off feel, while Fox’s CTD  shocks often wind up being too stiff or too subtle. Penske’s regressive damper technology – a design borrowed from the world  of F1 and adapted to mass-production  MTB applications – claims to strike the  perfect, seamless balance between the two  extremes. Using very clever mechanical valving, the RE:aktiv damper provides a  firm level of support when stomping on the  gas, but opens up seamlessly to absorb trail  impacts of all sizes—that’s the marketing  claim, anyway. 

I’m keeping my eye out for flying pigs, because this is one of those occasions  where the marketing hype is actually very  close to the truth. Leave the shock in its  open setting, where the RE:aktiv damper  doesn’t come into effect, and the EX 9.8  behaves as it would with any other Fox  shock in place. It pedals extremely well  whilst you remain seated, with virtually  no discernible movement. Standing efforts  in the big ring elicit a noticeable amount  of bob, but leaving the chain in the small  ring keeps the suspension composed due  to higher levels of chain-related anti-squat. The rear wheel stays planted on terra firma  over all sizes of bumps, and it’s one of the  most supple bikes available in the 120-130mm travel range. 

Flipping the shock-mounted CTD lever  to either the middle or firm setting brings  the fancy RE:aktiv damper circuits into the  equation. The mid-setting provides a subtle  but noticeable increase in suspension support,  either to resist pedalling movement or  bottoming the suspension on G-outs, or to push against when pumping over bumps or launching off the ground. The firm setting simply super-sizes these same effects, but without making the suspension feel totally unresponsive—it works far better than any ‘lockout’ is ever going to do.  With these settings there is a corresponding slight decrease in suppleness over trail chatter but it’s not much and it isn’t overly detrimental to the suspension performance. Just as the marketing suggests; when the hits come harder and faster the RE:aktiv shock opens up in a truly seamless manner, so that even in the firmest setting you can leave the shock alone, bomb a gnarly downhill or cruise through serious braking bumps without having to book a dental appointment the next week to replace your fillings.

The RE:aktiv shock does everything it claims, and from a trail riders perspective it feels better than an inertia valve design. Perhaps it’s better than Fox’s CTD system too, but the improvement here is much, much smaller; in a double blind test, I think the vast majority of riders would struggle to tell the difference between a well tuned CTD shock and the Penske beast. This is in no way a slight on the RE:aktiv damper, merely a credit to Fox who have also spent a lot of time and money refining their own MTB suspension technology.   

PERSONAL RE:AKTION

So here’s the thing; in order to balance the conflicting demands placed on MTB rear suspension, designers tend to go down one of two routes; either they refine the suspension kinematics to allow chain tension to balance unwanted movement, or they use clever damper technology to do the same thing. To use both techniques seems largely redundant, and Trek’s ABP system, especially when using a 32-tooth front chainring (around which it is optimised), simply doesn’t need a clever shock to behave neutrally.

Both the alloy EX 9 and the top-end EX 9.9 use a 1x11 transmission that’s based around a 32-tooth ring, and when we rigged our test mule with the same size chainring, we found that it behaved flawlessly without needing anything other than the open damper setting. It was efficient and traction-hungry on the climbs, lively and responsive on the flats, and supple and sorted on the downs. Having the RE:aktiv damper doesn’t make the EX 9.8 any worse, but it doesn’t really make it radically better either.

Personally I think Trek would have been better off putting the clever damper tech into a fork where it would really be of benefit. Kitting out the entire Fuel EX range with one-by transmissions would allow their already excellent suspension system do its thing, and it would do so with the regular DRCV shock. You may appreciate the stiffer damper settings if you come from a road or XC-race background, but I feel the performance gain is quite minimal once you’re on the dirt.
 

I’m also going out on a limb to say that the EX’s stiff frame and entirely sorted rear suspension are sold short by the skinnylegged, short-travel fork and steepish head angle. These days, many brands are fitiing their shorter travel trail bikes with more travel up front to boost confidence in the rough without losing agility and efficiency. I feel that the Fuel would also benifit from this style of setup; it would be an absolute beast of a trail bike with a 140mm travel Pike or Fox 34 up front.

As it stands it’s a perfectly good bike for moderate trails, but its capabilities in the chunder would improve astronomically with a more capable fork and the added height would serve to slacken the front end too.

Should you spend your hard earned on the Fuel EX9.8? That’s going to be a personal decision. If your trails or riding style doesn’t involve super technical or gnarly descents, it presents a well-rounded package based on a very well made frame and the proven ABP suspension. Personally, I’d opt for a frame-only with a build based on a burly fork and a one-by transmission, or simply spring for the alloy framed Fuel EX9. At $4,499 the EX9 already comes with a one-by drivetrain; a change that would come close to negating the weight gain from the alloy frame. The money saved could then be spent upgrading to a bigger fork and some wider, lighter wheels; two hop-ups that would enhance the ride more than the carbon frame alone. It’s certainly a great bike with some clever technology, but with a few changes the EX 9.8 could easily be one of the best trail bikes available.

Thumbs Up

• Refined APB suspension design

• Lightweight and stiff carbon frame

• Great handling for flowing terrain

Thumbs Down

• Would benefit from a one-by drivetrain

• Head angle on the steep side for some

• Untapped potential in the rough

SPECIFICATIONS

Frame: OCLV Mountain Carbon with alloy chainstay

Shock: Trek/Fox DRCV with RE:aktiv damping 120mm

Fork: Fox Float 32 Performance CTD 120mm travel

Headset: Cane Creek E2

Handlebars: Bontrager Race X Lite Carbon 720mm

Stem: Bontrager Race X Lite Alloy

Shifter: Shimano XT

Front Derailleur: Shimano XT

Rear Derailleur: Shimano XT

Cassette: Shimano XT 11/36 10-speed

Chain: KMC X10

Cranks: Shimano XT 24/38

Bottom Bracket: Shimano

Pedals: N/A

Brakes: Shimano XT

Wheels: Bontrager Rhythm Comp tubeless ready

Tyres: Bontrager XR3 Team Issue 2.3

Saddle: Bontrager Evoke 3

Seatpost: RockShox Reverb Stealth

Weight: 12.37kg without pedals (19.5 frame 2,410g)

Available Sizes: 15.5, 17.5, 18.5, 19.5 (tested) & 21.5 inch

Price: $5,899

Distributor: Trek Bicycles Australia www.trekbikes.com