Throwback Thursday: Trek Fuel EX 9.9 29

Trek Fuel EX 9.9 29

The Fuel EX is arguably the most versatile bike in Trek’s lineup and has long been built for real trail riders. Over the years, the Fuel EX has adapted to the demands of modern riding with various upgrades and tweaks but has stayed true to its intended purpose as a bike that can go all over the mountain, whether the trail is full of long and steep climbs or technical descents. Trek released a revamped lineup a couple of years ago that offered an all-new design with a new geometry and frame construction. This year the Fuel EX has essentially the same bones as the previous generation, but Trek had another card to play to improve the already tried-and-true platform. That came in the form of a new shock treatment that we decided to put to the test. After months of test riding and countless trail miles, the verdict is in on what Trek claims is the best iteration of its workhorse trail bike platform.


Trek designed the Fuel EX as a do-it-all machine for a huge cross section of riders looking for a bike that can handle a wide range of trails. Whether you are a cross-country racer looking for a weekend weapon or a dedicated trail rider in search of a bike to handle big backcountry days and technical terrain, the Fuel EX is ready and willing.


There are several levels of the Fuel EX, ranging from entry-level aluminum to the highest-end 9.9 model we tested. Our test bike came with a full carbon fiber frame with Trek’s Straight Shot downtube that stiffens up the bike when pedaling out of the saddle. Coupled with the downtube is a Knock Block headset that keeps the handlebars from over-rotating into the frame in the event of a crash. The rear triangle on the Fuel is 1x-specific and uses Trek’s Active Brake Pivot and Mino Link to adjust the geometry. At the heart of the new Fuel EX 9.9 is a new shock treatment called Thru-Shaft. This design also uses Trek’s RE:aktiv system that it licenses from Penske Racing. RE:aktiv was designed to give riders pedaling support, and RE:aktiv with Thru-Shaft has even more pedaling support. ThruShaft eliminates the Internal Floating Piston (IFP) that is currently used on most shocks and essentially eliminates oil displacement by doing so.


Trek spared no expense on the build kit with the 9.9. The SRAM Eagle XX1 drivetrain provided flawless shifting and gave us a wide-enough gear range for any type of riding. The SRAM Guide Ultimate brakes had plenty of adjustment and stopping power. Bontrager included a set of its new Line Pro 30 carbon wheels that were lightweight, sturdy and durable.


Moving out: Our test bike came with a set of 750-millimeter carbon Bontrager bars that gave our test riders a comfortable position. More aggressive riders may want to opt for something slightly wider. We dropped the stack height almost all the way down for a lower position and dialed in the saddle tilt. Once we had these minor tweaks done, the Fuel rewarded us with a somewhat neutral feel that wasn’t too low and stretched out nor too upright and rear-wheel biased.

Setting the Mino Link: The Mino Link allows riders to adjust the geometry, varying the bottom bracket height and the head angle. Our test bike was delivered in the high setting, putting the head angle at 67.7 degrees. We did our first bit of testing with it in the high position, but once we flipped the chips into the low setting, our test riders never looked back. The low position put the front end at 67 degrees and inspired more confidence at high speeds and in steep descents.

Suspension setup: Trek offers detailed instructions on its website on how to set up the Fuel. We followed the tips and started at 28-percent sag in the shock. This felt comfortable, but after a few rides we increased the air pressure and settled on around 25-percent sag for the duration of our testing. In the fork, we ran 20 percent with two volume reducers for a very progressive feel.

Climbing: There are plenty of trailbikes out there that claim to be good climbers, but the Fuel EX proved that it is way ahead of the pack in this department. The extra oil volume in the shock provided more pedaling support than the previous RE:aktiv shock and didn’t require our test riders to use the third position on the shock. Out of the saddle the Straight Shot downtube was stiff and responsive, with the rear triangle holding its own. The bike is lightweight, the frame is stiff and the suspension is supportive. Because of those attributes, this bike handles long grinder climbs as well as it does short and technical climbs

Descending: There is very little the Fuel EX can’t do with a talented descender at the controls. It will also make a beginner more confident, thanks to the dialed suspension and very natural and easy-to-use geometry.On descents, the Fuel was capable, controlled, and tracked terrain effortlessly at high speeds. The faster our test riders pushed, the better the bike felt, inspiring more confidence than a bike in this suspension category should. The Thru-Shaft treatment is very regressive at the top of the stroke, but still offers plenty of small bump compliance. Once the shock opened up the mid-stroke and bottom end, were incredibly responsive. The larger 29-inch wheels rolled quickly and conquered roots and rocks with ease. The sporty geometry made for a balanced yet playful feel, and the bike wasn’t afraid to get rowdy. Braking: Trek developed its Active Braking Pivot (ABP) to prevent brake jack on the trail. The combination of ABP and the Thru-Shaft treatment allowed for very controlled braking and increased traction, especially in emergency situations. The Guide Ultimate brakes had more than enough power and didn’t give us any unwanted issues during our testing.


There is little (if anything) to complain about with the stock build and performance of the Fuel EX 9.9. We did encounter issues with the stock Bontrager Drop Line post and had to replace the cartridge fairly early in our testing. The new shock has a comfortable-enough range of adjustment that set-it-and-forget-it-type riders won’t have any issues, while suspension nerds will be able to fine-tune the ride quality. If you want to squeeze every bit of capability out of the Fuel, switching to a slightly longer 140- millimeter fork will add to the rowdiness in all the right ways.


The Fuel EX 9.9 is one of the best trailbikes in this suspension category we have ever tested, and, considering the price, it should be this good. While the new shock is only available with the high-end and frame-kit options, the lower-end models embody the same spirit of mountain biking and are well worth your hard earned cash. The Fuel EX makes a strong argument for itself as a do-it-all trail machine that is pure fun to rip.


Mountain Bike Action is a monthly magazine devoted to all things mountain biking (yes, that’s 12 times a year because we never take a month off of mountain biking). It has been around since 1986 and we’re still having fun. Start a subscription by clicking here or calling (800) 767-0345.

Available from the Apple Newsstand for reading on your iPad, iPhone or iPod Touch.

Subscribe Here

2018 trek fuel ex 29 testbike testfull suspension 29ermountain bikemountainbikeNEWSre:aktivthru-shaftthrushafttop storiestrek fuel ex 9.9 29 review