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2015 Trek Fuel EX 9.9 27.5 Bike (discontinued)

Vital Rating: (Excellent)
Trek Fuel EX 9.9 27.5
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Tested: Trek Fuel EX 9.9

Rating: Vital Review

Review by AJ Barlas // Product Photos AJ Barlas, Riding Photos Jon Anthony

Almost a full year ago now, Trek revealed to the world a special sauce they'd been working on with top motorsports racing outfit, Penske. That technology was the RE:aktiv damper, a unit that took onboard Penske's advanced regressive suspension tech used in their F1 race car suspension, and a range of similar applications.

After initially enjoying a couple of days aboard the RE:aktiv equipped Trek Fuel in South Carolina, we were eager to spend more quality time on this bike and suspension technology, on trails we commonly ride in the Pacific Northwest and Sea to Sky region. After a number of months now and a range of incredibly varying conditions, we're happy to report on our experiences with this very interesting, shorter travel trail bike.


Trek Fuel EX 9.9 Highlights

  • OCLV Mountain Carbon frame and stays
  • 27.5-inch wheels
  • RE:aktiv DRCV Fox rear shock
  • 120mm (4.7 inches) of rear wheel travel // 120mm (4.7 inches) front travel
  • E2 tapered headtube
  • 68 degree head angle
  • 73 degree seat tube angle
  • 333-mm (13.1-inch) bottom bracket height
  • 433-mm (17.1-inch) chainstays
  • BB95 bottom bracket
  • 142-mm rear spacing with 12-mm through axle
  • Measured complete weight (size 21.5-inch, no pedals): 25-pounds (11.34-kg)
  • MSRP: $8,799.99 USD

Initial Impressions

Black beauty! Who would have thought that an almost fully blacked out bike with barely legible branding could look so, so sharp? The black chrome XTR 1x11 on the 9.9 was the icing on the cake!The rest of the OE spec on this build is absolutely dialled as well, both in regards to appearance and functionality, but it all comes at a price. If looking to ditch the front mech but carbon is not a must, there is an aluminum version available for $4,299.99 USD.

This trail bike is light - the lightest XL bike we have ridden that is still capable of ripping aggressive single track, while also entering an XC race. Our stock build came in at 25-lbs on the nose (11.34-kg) and with the bar/stem switched for a shorter/wider set-up and the tires swapped for some more aggressive rubber, it weighed in at 26.7-lbs (12.2-kg). The light weight was instantly noticeable on the trails, making it very easy to move the bike around, or accelerate quickly and efficiently.


We set the bike up with 25% sag in the rear and 20% up front; about 5 clicks of rebound damping in the rear (from full open) and 4–5 clicks in the front. After a parking lot test we were fairly happy with these initial settings and set out on the trails to gather up some real world experiences.

On The Trail

Since early December, we've been riding the Trek Fuel EX 9.9 on everything in the Sea to Sky. From aggressive downhill trails on Cypress, parts of the classic North Shore network of Vancouver, to the flowing tech of Pemberton, the Trek has seen a wide array of terrain. Conditions for this time of year have also been a challenge for equipment, with monsoons and the wettest trail conditions experienced in years, frozen solid velcro dirt and ice, to dry, dusty loose dirt and heroic brown pow; the Trek has literally seen it all.

Without a doubt, the RE:aktiv damper is the key piece, or heart, of the updated Trek Fuel series. The technology was first taken to the trails mostly as an external addition to Trek's already established DRCV, until such a time that Trek and Penske were happy with the ride characteristics. Once they reached this point the shock was passed along to the clever tech team at Fox, in order to make the technology ready to build for the masses.


This partnership resulted in a damper that has the ability to create a solid platform for both rider and smaller external inputs, yet when a larger velocity impact occurs, the valves open and the suspension takes action. This is different to the more common tactic of shutting off the valves altogether, or at least heavily restricting their ability to allow oil through, and it grants riders a little of the best of both worlds. A strong platform to mash on, but retaining the ability to smoothen out the trail and theoretically, retain traction when climbing more technical terrain.

Wide open, the rear shock was very neutral when adopting an efficient pedal technique and climbing in the saddle. However, standing was another story altogether, with the bike liking to bob a bit more than we're used to. Despite the improved platform that the RE:acktiv damper provides, the Fuel still likes to have the dials flipped in order to show riders its most efficient climbing traits; similar to Trek's of the past.

In "Trail" mode - the middle compression setting - the bike climbs very well, retaining reasonable traction thanks to the damper's ability to accommodate higher velocity hits. This was, in our experience, the most useful mode for climbing, as we found the "Climb" position was too harsh. The result was opting not to use the "Climb" mode unless ascending bitumen roads.


Another thing to consider with the RE:aktiv damper is that because it shuts off the low speed, or low velocity impacts, it remains quite high in its travel when using the Trail mode, and even more so in Climb. If pedal strikes are a common issue on a particular piece of trail, or you're approaching an incline that would benefit from a steeper headangle, flipping the compression dial will assist greatly with this. We did find a downside on the climbs though…

The terrain that we rode the Fuel EX 9.9 on was primarily rooty and rocky, mixed with loose dirt. Climbs ranged from mild and smooth, to very steep, rubble infested hills. If the dial was flipped to either Trail or Climb, we found that the Fuel would loose traction in some situations that it probably shouldn't have, with the damper struggling to react enough for the small, traction sucking, looser terrain. Obviously this would be the same, or worse, for many of the dampers already out there, and the RE:aktiv damper did outperform these in some situations, but was not far ahead when it came to loose, smaller root and rock infested climbs.

Leaving the rear shock wide open in these situations it was amazing, but the obvious downside was that it required a little more effort and a more aggressive body position to beat the trail. We generally preferred to leave it wide open and allow the suspension to track the ground on the more technical climbs experienced in the Sea to Sky, opting to run it in Trail mode for moderate climbs and dirt roads, and flicking it to Climb mode on the bitumen - which wasn't often. The 73º seat tube angle was pretty average, especially given the more aggressive angles showing up on geo charts nowadays. Had it been 1º, or even 0.5º degree steeper, it would have helped with positioning on the tougher, steeper and more technical climbs we encountered.

When descending, the Fuel came to life! We opted to leave it wide open after some initial experiments resulted in the bike being too harsh in Trail mode. Our initial couple weeks of riding resulted in some large bottom outs, front and rear, with the suspension wide open. The first major one was within 100ft of trail on Cypress, with the bike bottoming at both ends, hard enough that we felt and heard it happen. This was not the first time we had bottomed the bike's clever suspension, but the first time that it was so pronounced - real hucker head banger type bottoms, sounds and all. It happened another 4 times that ride, each as harsh and obvious as the first. In the bike's defense, it was in beyond its pay grade when these and others happened, but it's worth noting these limitations.


These situations resulted in the 32 up front being flipped to Trail mode pretty early on, as descend mode was deemed pretty well useless for us. With the fork in the Trail setting we were also more well balanced front to rear, granting us a good deal of confidence when coming into rougher corners hot, or in steeper, chunky terrain. Unfortunately the same for the rear didn't cut it, with the suspension losing a lot of its finesse in Trail mode, and no longer tracking the terrain suitably. It was especially noticeable on high speed chatter and successive medium sized hits.

At this point we decided to utilize the Push volume reducers. These little beauties go in the top of the shock, are super easy to install and make a world of difference if seeking a more progressive end stroke, or some more mid stroke support. We wanted the changes to be incremental, and began with the smaller of the two 'chips'; the 7-cc volume reducer. With this installed a slightly more supportive mid stroke was noticed and it ramped up nicely at the end to prevent the harsh bottom out we were experiencing without it. The suspension performed exceptionally, tracking the ground well and utilizing the travel efficiently, while remaining well balanced with the front.

After some experience with the 7-cc reducer, it was time to try the 10-cc version. We found that for a 165-lbs rider this was too much, and provided a rougher ride. The ramp of the suspension was noticeable earlier in the travel and was not something we were enjoying in more technical terrain. Even on larger hits it was too abrupt, resulting in the bike being unstable on impact. The 10-cc reducer also threw the balance off and during steeper descents we found ourselves being pushed over the front too much. Adjusting the fork at this point to level it out would only have resulted in a loss of front end traction which would not have helped the situation.


The bike still handled reasonably well on flow trails and jumps, and we could see this being a potential benefit to a heavier rider, but it had lost its butter smooth traction experienced both with the 7- cc reducer (or no reducer at all). For us, the 7-cc option was the reducer of choice and remained in the shock for the majority of the test.

With the 7-cc reducer installed and the Fox 32 Float set to Trail, the bike excelled. The rear suspension is very, very predictable and reliable, never doing anything unexpected and always where we wanted it. The rear suspension did outshine the 32 up front, leaving us wanting more. Despite this being a 120-mm trail bike, it can punch above its weight class! It was in these situations that the fork would be noticed, simply because it wasn't keeping up. In fast, rough descents with large compressions it felt as though the fork was being stressed to the limit, at times with a "the front end is going to collapse, or tear off" kind of feeling, yet the rear remained composed.

The ability to really see just how high above its weight class the Fuel could punch was hindered somewhat by the front end. The 32 could not take high speed, consecutive medium sized hits or deep compressions the way the rear could, often resulting with us off on some tangent that we never intended to be on, or worse, in the bush next to the trail. It was unfortunate how distracted the fork was in this type of terrain, with the rear of the bike seeming like it would be up for more while the front end wandered off to do its own thing.


Putting the Fuel EX on 'flow trails' means preparing for a good time. Cornering, the bike was on rails thanks to its low 13.1" bottom bracket and its predictable nature. It jumps incredibly well, urging you to lift harder and huck as far as possible, off everything! The light weight coupled with the geometry had it feeling akin to a BMX bike down at the local skatepark - try not to smile when jibbing flow lines down the hill on this bike; it's not possible! In fact, it reignited a whole style of riding in us that we had almost forgotten, and we're so glad that it did.

Build Kit

The Trek Fuel line comes with Fox suspension front and rear. Our 9.9 test bike was fitted with the 32 Factory Float up front, a fork that as mentioned, struggles to keep up with the rest of the bike in technical situations. The rear is the evolution of Trek's custom tweaking and new partnerships, with the Fox manufactured DRCV shock receiving additional love by way of the RE:aktiv technology developed with Penske. The damper performs well, but really excels when special attention is taken to set it up correctly for your riding style. Flipping the compression dial will assist on the long grind climbs, but we found it to track better wide open when in more technical climb scenarios.

Taking care of transmission duties was the new 11 speed Shimano XTR kit. In typical Shimano fashion, the shifting is impeccable. Quick, sharp shifts in pretty well any situation, regardless of thick mud, trail debris, or poor execution, it does a great job. The appearance of the new XTR crank is better in the flesh as well, but cover the arms up with some clear tape - our cranks showed noticeable signs of wear after the first ride. The Fuel also came without a guide and was the only 1x unit that we have not dropped a chain on. Some have lasted a fair amount of time prior to dropping, but eventually did and perhaps that would happen here once there is more wear. Nevertheless, it was flawless during testing.


The gear range on our test bike was taller than some may enjoy, fitted with a 34t front chainring and a cassette that maxed out at a 40t, while the other end was an 11t. We found the range to be fine for our terrain and long limbs, with only the most aggressive of climbs resulting in a click up into the 40t. When doing this it was a quick, smooth change, with no delays or stalls in the process. During testing, the drivetrain has needed little more than chain lube and one twist of the barrel adjuster - pretty impressive!

The Shimano XTR brakes performed as many have come to expect. They're consistent, don't fade, don't do anything unexpected and slow the bike down in a heartbeat when needed. They do offer less modulation than we prefer, but once we got used to them it wasn't an issue.

The Bontrager Rhythm Elite wheels could be deemed a little 'light' for the performance this bike is capable of delivering. The inner rim width is narrow, making for a bit more tire squirm than we would like to have. Upping the pressure a couple of psi helped curb this, but is not ideal. They also were softer than what we commonly ride, adding to our unsuccessful line choice at times and lacking a little zest when exiting corners. Our test bike wheels also seemed to feature a higher end hub than the stock Rhythm Elite wheels - one that had Bontrager's Rapid Drive Engagement which was a nice touch.


We swapped out the stock Bontrager XR3 Team Issue tires, which may perform okay in hardpack, but generally didn't grant any confidence in the terrain they were tested in. Initially they were ridden in wet conditions, which they definitely have no place in. They were replaced with a firmer sidewall, more aggressive set of Maxxis EXO treads, which we chose to setup tubeless. This was very straightforward and simple to accomplish with a hand pump, thanks to Trek's TLR system.

The bar and stem that came on the bike were beautifully made carbon numbers, but that's where their draw stopped. The bars, at 740mm wide, are not only generally too narrow for the size of human that will typically ride an XL frame, but they lack the stability granted in stressful situations with the wider bar. Add to that the 90mm stem (you read that right) and we had to laugh. They were replaced with a 780mm bar and a 40mm stem, centering us on the bike perfectly and granting a comfortable riding position.


The bike arrived with a stealth Rockshox Reverb, which performed flawlessly during the test. The internal routing kept the bike looking sleek. Unfortunately it came with a left side lever, despite the bike being specced as a 1x. Given the 1x drivetrain, we would have preferred a right side lever, flipped and placed under the bar on the left side. Something that many riders do when running Reverb posts and 1x systems.

We should also mention that the bike is incredibly quiet, with no cable clang thanks to the clever mix of internal and external routing. The brake line runs externally along the top of the down tube, making for easy servicing and access, and is mated with the stealth Reverb line, which ducks into the frame through the down tube, as it nears the bottom bracket junction. The rear gear cable runs internally and is tensioned, preventing it from making any noise inside the frame.


Things That Could Be Improved

Given the potential trail destroying abilities of the Fuel EX, a more capable fork than the spec'd Fox 32 would be a good starting point for improvements. We feel that aggressive riders will get a lot more out of this bike with something like the Fox 34, or perhaps a Pike (we know, there it is again). Either of these would increase the bike's already impressive abilities and perform in line with the rear of the bike. For the less aggressive, or those riding in smoother terrain, the 32 will work fine.

The 90-mm stem that came on our Fuel seemed ridiculous. We completely understand that this is a trail bike, but with the long and low geometry, something that the industry has been pushing toward for some time, why there was a stem reminiscent of something from the Tour De France, circa 1995 (only in carbon), on the front of the bike is puzzling. Fitting this bike with a 50- or 60-mm stem seems totally reasonable to us - the 90-mm that came on it was just alien.We would also have preferred to see a Reverb lever that can be placed underneath the left side of the bars. It's a more natural and easily accessible position and it also keeps the lever out of harm's way a lot better. It's a minor gripe, but nevertheless, an oversight in the spec.


The persistence to spec narrow bars is growing tiresome as well. Educate retailers to cut bars down when the consumer needs it, rather than require the customer to either ask for an exchange, or purchase a different bar from the get-go. If not for all frame models, at least for the those size large and up. Add to this, that if throwing down large for a new bike then generally the exchange of parts should not come into play, at all. Obviously some riders are going to tinker and customize to their preferences, but we still feel it should be a solid build from the get go, with any part swaps done purely for the sake of personalization.

We found that the stack height for the XL was too low and even with the stem perched above 3 10-mm spacers and a set of 20-mm rise bars, an extra 5-mm would have been nice. It would be appropriate to allow for little adjustment up, or down, rather than simply being at the upper limits of the frame. We also feel that a slightly steeper seat tube would help with the bike while climbing in technical terrain, placing the rider a little more over the bottom bracket. It climbs reasonably well, but could be better.

Long Term Durability

The Trek Fuel frame has seen a good amount of action since early December and has needed little by way of maintenance. The frame is running great, with the bearings still friction free and tight. The Shimano drivetrain has been flawless as well, despite seeing some ugly conditions. Our rear wheel is out of true, but not terribly so and the rear hub has come loose as well. Aside from these and given our experiences thus far, we don't see any long term issues with the bike outside of regular maintenance.

What's The Bottom Line?

A bike that's this much fun on flow trails and pretty capable in technical terrain should be illegal - the country will lose all sense of productivity as hordes of people flip work the bird and head out to ride as much as they can humanly manage! The Fuel isn't without its nuances in stock form, but it's a more common trend than one would think it should be. The fork struggles to keep up in aggressive situations, however, outside of these situations the whole package performed flawlessly and were it not for the overall capabilities of the bike, we doubt we would have even noticed the fork struggling.

The Fuel is composed, predictable and inspires a surprising amount of confidence for such a small bike. It has its limits, like any 120-mm trail bike but despite these, we think it's of the more capable in its class. If seeking a smaller travel do it all bike and money is not an object, then the 9.9 is a must look. If the price tag of the 9.9 is a bit much, most of the ride characteristics can be obtained in lower tiered packages.

For more on the Trek Fuel EX 9.9, check out

About The Reviewer

AJ Barlas started riding as most do, bashing about dirt mounds and popping off street curbs. Not much has changed, really. These days the dirt mounds have become mountains and the street curbs, while still getting sessioned, are more often features on the trail. He began as a shop monkey racing downhill since day zero, only to go 'backwards' and start riding and racing BMX later on. He then came full circle once moving to Whistler. AJ loves riding everything from 8 hour mountain pass epics (bonking) to lap after lap in the park and 20 minute pumptrack sessions at sunset. Driven by his passion for biking and exposing people to the great equipment we ride, AJ started and maintains the Straightshot MTB blog. So long as wheels are involved, and preferably dirt (the drier and dustier the better), life is good.


Product Trek Fuel EX 9.9 27.5 Bike
Model Year 2015
Riding Type Trail
Rider Unisex
Sizes and Geometry
15.5", 17.5", 18.5", 19.5", 21.5" View Geometry
Size 15.5" 17.5" 18.5" 19.5" 21.5"
Top Tube Length 21.85" 23.15" 23.94" 24.68" 25.71"
Head Tube Angle 68° 68° 68° 68° 68°
Head Tube Length 3.74" 3.94" 4.33" 4.72" 5.51"
Seat Tube Angle 73.0° 73.0° 73.0° 73.0° 73.0°
Seat Tube Length 14.49" 16.50" 17.52" 18.50" 20.51"
Bottom Bracket Height 13.11" 13.11" 13.11" 13.11" 13.11"
Chainstay Length 17.05" 17.05" 17.05" 17.05" 17.05"
Wheelbase 43.35" 44.76" 45.47" 46.06" 47.01"
Standover 29.13" 28.74" 28.74" 29.13" 29.21"
Reach 14.72" 16.34" 17.01" 17.68" 18.46"
Stack 22.05" 25.79" 22.60" 22.95" 23.70"
Wheel Size 27.5" (650b)
Frame Material Carbon Fiber
Frame Material Details OCLV Mountain Carbon Main Frame and Stays, Carbon Armor, Internal Derailleur and Dropper Post Routing
Rear Travel 120mm
Rear Shock FOX Factory Series Float, DRCV, RE:aktiv, CTD Damper, Rebound, Kashima Coat, 7.25"x1.875"
Fork FOX Factory Series 32 Float, CTD, FIT Adjust Damper, Rebound, E2 Tapered Steerer, Kashima Coat, 15QR
Fork Travel 120mm
Head Tube Diameter Tapered
Headset Cane Creek IS-3, E2, Carbon Cartridge
Handlebar Bontrager Race X Lite Carbon Riser, 31.8mm, 15mm Rise
Stem Bontrager XXX, Carbon, 31.8mm, 7°
Grips Bontrager Race Lite, Lock-On
Brakes Shimano XTR Trail Hydraulic Disc
Brake Levers Shimano
Drivetrain 1x
Shifters Shimano XTR, 11-Speed
Front Derailleur N/A
Rear Derailleur Shimano XTR, Shadow Plus
Chainguide N/A
Cranks Shimano XTR
Chainrings 32 Tooth
Bottom Bracket BB95
Pedals N/A
Chain Shimano HG900
Cassette Shimano XTR, 11-40 Tooth, 11-Speed
Rims Bontrager Rhythm Elite Tubeless Ready Wheels with TLR Strips
Hubs Bontrager Rhythm Elite Tubeless Ready Wheels with RapidDrive
Spokes Bontrager Rhythm Elite Tubeless Ready Wheels with Stacked Lacing
Tires Bontrager XR3 Team Issue, Tubeless Ready, 27.5"x2.35" Front / 27.5"x2.20" Rear
Saddle Bontrager Evoke RXL Carbon, Carbon Rails
Seatpost RockShox Reverb Stealth, 2-Bolt Head, Zero Offset
Seatpost Diameter 31.6mm
Seatpost Clamp Standard
Rear Dropout / Hub Dimensions 142mm x 12mm
Max. Tire Size
Bottle Cage Mounts Yes
Colors Matte Carbon Smoke/Gloss Dnister Black
Warranty Lifetime for Main Frame, 5 Years for Frame Swing Arm
Weight N/A
Price $8,399.99
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