One of most noticeable things right off was how easy climbing was. Hills suddenly seemed a lot smaller on the Fuel. Trek would probably have you believe that this was due to the DRCV (dual rate control valve) custom tuning on the rear shock that you can only get from Trek, but I have a sneaking suspicion that the big wheels and light carbon frame helped too. Weight came in around 28lbs with pedals, which is pretty respectable for a full-suspension. The DRCV is designed to absorb big drops as effectively as repetitive small bumps, achieved by essentially adding a secondary air compartment to the shock that only kicks in when a small plunger opens it up for "big hits." At this point the technology has become a little overtaken by Trek's own Re:aktiv, and it doesn't help the bike stand out a whole lot while Specialized has Brains. That doesn't mean it isn't effective though, and only when it was fully open did I ever notice any significant loss of power to my own personal bouncy house.
The fork is similarly well performing, equipped with Fox's CTD. While Trek did experiment with DRCV for forks on the 2013 Fuels, for 2014 they skipped it. I doubt I would have noticed either way, but it's probably good to keep the fork as simple as possible. In spite of that, I did notice that the fork, one of Fox's Evolution series, did tend to make some unsettling noises now and then. I never had any issues with a lack of stiffness, even through the best tended rock gardens, but every so often the fork would let out a squeak or a slight grating sound.
As always, Shimano makes an excellent showing with their SLX brakset. Power is great, modulation is decent, and reliability is beyond belief. Out of the box the rear-brake was a little spongey, but after a quick bleed there weren't any more problems even in horrible conditions. Only the slightest of noise in the wet, and certainly ready to stop you whenever you need them too.
Grips, saddle, and cockpit were all pretty standard and well-performing, though for extra long days of riding a replacement may have to be considered for Bontrager's stock Evoke 2.
While the bike felt quick and lively up climbs, taken through rough rock gardens or technical descents it was easy to tell that the bike was out of its league. The Fuel is a trail bike, but it tends to be more comfortable as a race machine and through mild singletrack rather than tackling rocky declines. This isn't strictly due to the geometry, as the 7-degree stem has enough range to accommodate steep climbs or descents with little sweat, but the wheels seem to let the bike down as a whole. Even the suspension can handle everything but daredevil-esque drops with ease, but the wheels are as wiggly as Wacky Waving Tube Man. Hard accelerations and technical jittering certainly made me notice the flex in the rear wheel. Even after upgrading the tyres to the noticeably more grippy XR4s (as opposed to the stock XR3s), it was sometimes difficult to stay afloat in rock gardens because the lack of stiffness in the rear wheel meant it tended not to keep its line very well. After only 1 year the freehub also gave out and had to be replaced. Fortunately this fell within Trek's 2-year parts warranty, but others may not be so lucky.
Wheels are a bit of a let-down already, but one of the biggest shocks about how this bike is spec'd comes from the drivetrain. Stock, the 9.7 comes with a 3x10 Shimano XT Drivetrain. That wasn't a typo. 3 chainrings in the front. For a carbon full suspension mountain bike in 2014, 3x10 makes very little sense. I only ever used the largest ring on paved downhill sections in between trails, and even the smallest ring felt a little too low for most of my riding. Eventually I switched to a 1x10 SRAM drivetrain, which made every pedal stroke feel instantly more efficient and made the right gear a lot easier to find. This isn't a hard upgrade to make, but the fact that a company like Trek is so out of touch on their entry-level carbon singletrack bike in this way does not bode well.
For the time that I rode it, I liked this bike very much. It felt smooth, it felt right, and it's a shame that Trek let the bike down in its spec, because even just with a slight drivetrain upgrade it would have been an excellent buy. Because of the poor wheel and gearing choice though, the $4020USD price tag just doesn't sit well, even if you have that kind of money lying around. A better choice would be to swallow the extra 1.5k or so for the 9.8, or try out another brand's equivalent.
In the end, the Fuel EX 9.7 was a fantastic bike for singletrack and the occasional race at a great price, but it would have been nice if the office-monkeys at Trek had spent a little more time thinking about mating the great frame with a more suitable gruppo.
Rating: An Unfortunate 3.5/5