Trek Fuel EX 9.7

Review | The 2019 Trek Fuel EX 9.7 is a tech-heavy trail bike that rips hard

by 3

As part of a head-to-head review feature, Rob’s been testing two 130mm travel 29er trail bikes; the 2019 GT Sensor Expert and the 2019 Trek Fuel EX 9.7. So which one has come out on top? Read on for Rob’s review of the Trek Fuel EX.


The Fuel EX platform has been kicking around now for what seems like forever. Well, since 2005 to be precise.

What started out as a 100mm front and rear travel XC machine, the Fuel EX has slowly but surely evolved into a 130mm all-round trail ripper. Getting longer, slacker and more aggressive in that time, the Fuel EX is now available in a staggering 18 different models and specs, plus five women specific bikes.

Here, we have the 9.7 model, which sits second from top in the line up. With 29in wheels and 130mm of travel, the Fuel EX 9.7 is, on paper, a do-it-all everyday trail bike.

Trek Fuel EX 9.7
Aesthetics to please all eyes, the Fuel EX looks neat from all angles.

The 2019 Fuel EX 9.7

This model is finished in Matte Sandstorm and Trek Black which may split opinion, but is very refreshing to see a bike that isn’t full black. The Fuel EX 9.7 uses a OCLV carbon front triangle, bolted to an alloy rear triangle with Boost 148mm spacing front and rear.

The carbon used for this frame adopts what Trek calls, Retained Strength technology. Basically it’s where Trek has used different composite materials in unique layups in and around the downtube to reinforce the carbon. The Fuel EX also uses a piece of rubber armour on the underside of the downtube for further protection.

Trek Fuel EX 9.7
A large rubber armour plate aims to stop rock strikes damaging that carbon downtube.

Staying on the frame, the Fuel EX really has got more aggressive the older it’s got. The angular kink in the top tube, and the beefy tubes used in the carbon front triangle give it a very similar aesthetic to larger models in the Trek line up – the Remedy and Slash.

Up top we’ve got Trek’s Knock Block technology. This system has allowed Trek to use a straight downtube on the Fuel, (rather than curved), apparently to improve stiffness. Knock Block is an integrated frame protection system comprised of a special stem, headset top-cap, spacers and a chip in the frame. This stops the bars from spinning too far, to prevent the fork crown from hitting the beefy and uncurved Straight Shot downtube.

Trek Fuel EX 9.7
Treks Knock Block system works well, but if you’re wanting to put a non-Trek stem on, you’ll have to faff.

Out back you’ll find the Active Breaking Pivot (ABP) located on the seatstays. This sees the brake calliper rotating around the rear axle, which aims to reduce the effect braking has on the suspension action.

2.4in is ‘officially’ the largest 29er tyre that you can fit into the back of the Fuel EX. Depending on the tyre and rim combo, I’d say there’s clearance in there to go wider. You can also fit 27.5+ wheels into the Fuel EX chassis (with clearance for 27.5×2.8in rubber), though Trek recommends upping to a 140mm travel fork to lift the BB back up to acceptable levels.

Mino-Link is Trek’s own geometry adjustment system that allows riders to flick between two geometry positions, through a simple Allen key operated bolt. Flipping the link adjusts the head angle by 0.5°, and can raise or drop the BB height by up to 10mm. All without having any sort of negative effect on the suspension performance.

Trek Fuel EX 9.7
The Mino-Link is one of many pieces of tech that work so well on the Fuel.

To suit my 6’2″ (188cm) height, I’ve got the largest available size on test; a 21.5in that’s apparently suitable for riders up to 6’5in tall. Looking at the numbers (and in the high Mino-Link position), we’ve got a 67.7° head angle, an effective seat tube angle of 74.7° and a reach of 487mm. Chainstays are a compact 432mm in length, with the overall wheelbase sitting at 1214mm.

There’s a pretty clever rear shock too. The Fox Performance Float EVOL shock utilises Penske-developed RE:aktiv damping technology, which aims to provide a firmer and more efficient feel while pedalling, with a rapid transition to plush performance when you encounter bumps on the trail. All without need for electronics, handlebar levers and extra cables.

Trek Fuel EX 9.7
Switching between settings whilst riding, so you can concentrate on enjoying yourself.

Getting This Bad Boy Rolling

Out of the box, the Fuel EX was super easy to get rolling. One thing we always say is to make sure all bolts are tight before you take any bike out for it’s first ride though.

I’ve included that…because I didn’t do it. And it wasn’t long before the Bontrager dropper post lever bolt decided to wind its way out on a rainy day in the Lakes.

Somehow, after walking back up the trail I spotted the bolt sat in the middle of the trail like a diamond in the dirt. Note to self – always tighten bolts on a new bike.

Trek Fuel EX 9.7
The stock Bontrager bar runs at 750mm wide, which these days is narrow for a bike of this nature.

While the Knock Block is a neat system, loading the bike into a car or van is however, a touch annoying as you can’t turn the bars fully to get it stowed in a tight space. You’ll also have to leave the X-Up manoeuvres at home.

For a bike of this nature, the 750mm wide handlebar is narrower than what many comparable bikes are coming with. Still, I was keen to give it a go to begin with and see how it performed.

After the first few rides though, and especially riding back to back on a bike with a wider cockpit, the stock bar just felt too narrow. That saw me swap out the cockpit for something a bit wider, and a bit shorter.

Trek Fuel EX 9.7
Updated cockpit saw me use a 800mm wide Nukeproof Warhead bar and shorter stem.

A few points to note when changing cockpit.

First up, if you want to use a non-Knock Block stem, you’ll need to get a special Trek locking spacer that fits to the Knock Block spacers to make the system work. This simple-looking spacer will set you back £17.50. Once this is in place, you can use any stem you desire.

Secondly, I had to use no less than four different size Allen keys to swap the bars and cockpit over. Personally, this kind of thing really annoys me. Note to bike manufacturers: let’s minimise the different bolts and tools required – not just for the cockpit, but the whole bike.

Trek Fuel EX 9.7
Having to use four different allen keys just to swap over the bar and stem is mega frustrating.

To help with setup, Trek offers a comprehensive suspension calculator on its website. After inputting my weight, Trek recommended that I should run 80psi and 19mm of sag (15%) in the fork, with 200psi and 15mm sag (28%) in the shock. Worth noting is that both of these sag measurements are taken with the rider sitting stationary on the saddle, and not standing up. Trek also has a useful YouTube video showing how to setup the suspension.

Those pressures sounded a little low to me, but I went ahead with its recommendations, and headed out for the first ride.

After a few runs at the local, my hunch proved correct, so I bumped the shock up a little to 215psi and the fork to 95psi. For that ride, I also started with the Mino-Link in the high geometry position, with the aim to flip it around during the test period.

Trek Fuel EX 9.7
RE:aktiv suspension technology on the Fox Float Evlo has been impressive.

The Ride

Early impressions of the bike were really positive. Uphill, the Fuel EX sat into the travel well, but I did encounter quite a bit of bob from the shock. The initial air pressure tweak helped to firm things up through the pedals, though it’s worth noting that the Fuel EX’s Full Floater suspension design is quite active all-round. That means as you head upwards, it will happily settle into its travel – perhaps a little too happily.

At this point it’s worth engaging the blue compression switch on the RE:aktiv-equipped rear shock. Climbing in the Medium position not only provides a boost to pedalling efficiency, it also lifts the ride height of the bike and prevents the shock from sinking too deep into its travel. Because of the quick-acting RE:aktiv damper though, the shock opens up with impressive accuracy as your rear wheel encounters rubble on the trail. Even on rough, traction-poor climbs, the Medium shock position works well to balance efficiency and ground-hugging grip, all while keeping you in a commanding riding position.

If the climb is smooth enough, or you’re on tarmac, flicking into the Firm position will provide even more platform. While I wouldn’t ride technical ascents in the Firm mode, the breakaway threshold is still quick enough that if you forget to flick it back into the Medium or Open mode, the suspension works if you hit big enough impacts.

Trek Fuel EX 9.7
The superb climbing performance on this bike has made going uphills fun. Photo: James Vincent.

The initial riding position was great while pointing downhill – especially on steep terrain – but on the flats and uphill the bars felt quite high. I did swap a few spacers out to drop the bar and hand position a touch, which helped a lot. From the get-go though, the Fuel EX feels comfortable both climbing and descending. The position you sit in, even on this, the largest frame, is ideal.

It rolls fast on compact trails, and on the looser stuff is direct through the corners and confident. Comfortable and controlled on all trail types, and it never feels as if you’re losing your line or your way.

The BB height on paper doesn’t sound particularly low, but with the shock set to the Open mode, the supple suspension does mean the pedals come closer to the ground. While I did try the Low setting, I found the even lower BB meant I was clipping pedals and shoes too much. After playing around with the Mino-Link, and preferring the High position, I settled on that and left it there for the remainder of the test.

Trek Fuel EX 9.7
Dashing through the woods…

When laying down the power, the acceleration feels very subtle. Like a car with really low end grunt, the Fuel EX isn’t as snappy as others, but it still pulls away without having to put too much effort in. A slow, yet strong pedal stroke gets the bike going, and it’s a case of maintaining rhythm and you’re away. On the longer climbs, the bike has a work horse attitude feel to it.

It’s not the sharpest ascender though. There are bikes out there with lower and more aggressive front ends for slicing and dicing uphill switchbacks, and you’ll have to lean over the grips to ensure the Fuel EX keeps chugging up the line you want to take. The weighty wheels and high-volume tyres also subdue some of the Fuel EX’s climbing zest.

After descending and then pedalling into a sharp climb, I did find the Bontrager dropper post was sticking quite a bit when trying to return the post. This was both in the lever end and the actual post itself. Even when cleaned down and all mud removed it was an issue that carried on throughout the test and was incredibly annoying. Not having that immediate return from the dropper was irritating.

Trek Fuel EX 9.7
The Bontrager dropper post has been very inconsistent throughout testing.

Get the Fuel EX pointed downhill and this bike absolutely gobbles up low and high-speed sections of trail with ease. The big wheels and tyres roll fast and grip well respectively, letting you plough through loose, rocky sections without having to think too much. The Bontrager XR4 tyres have performed really well, offering plenty of traction and grip on most trail types. They reach their limit on really wet and boggy trails though, where they start to feel as if they’re wandering a touch. An XR5 up front would be a great addition for all-condition riders.

Setup with the wider bars and shorter stem, the Fuel EX allows you to command an authoritative position. It’s easy to shift your weight around the bike and drag it to where you need to be. Descents were tackled with much more aggression and I felt braver and more confident straight away. The wider hand position gave stability on the faster, looser descents, and is a no-brainer upgrade as far as I’m concerned.

Trek Fuel EX 9.7
Great traction from the tyres gives you confidence to throw the bike into the corners. Photo: James Vincent

When hitting jumps and popping around the trails, I found I bottomed the Fox 34 fork multiple times. I do prefer running slightly higher pressures and firmer suspension on trail bikes, and adding that extra pressure early on did help to stop the fork from bottoming. However, if you’re on the heavier side, consider adding volume spacers to the fork’s air spring if you want to maintain the supple initial feel while getting the bottom-out support you need.

It would be interesting to try the Fuel EX with a slightly longer fork though, which would slacken out the geometry a touch and add some more travel to get stuck into. Speaking with Jez Loftus at Trek Bikes, I heard that a few staff riders do run a 140mm fork on this bike, Fox 36s in some cases. This is entirely plausible, since the Fuel EX frame is rated for use with a 140mm travel fork. If you went down this route, you could also make better use of the Mino-Link’s Low position to keep the BB height level, while slackening the head angle even further. Mini-enduro bike anyone?

Trek Fuel EX 9.7
Would a longer travel fork on the Fuel make this bike even better? We’d love to have a play in the future.

As it is though, when you’ve got your suspension dialled, at speed, the Fuel really does rip along. You feel planted in the bike and once you’ve let off the brakes, it’s easy to get up to alarming speeds.

The suspension throughout the test, has been super supple and comfortable both front and rear, delivering plenty of control and grip. Coupled with the RE:aktiv shock, the ABP pivot system ensures the back end remains active so you’re less likely to lock up the rear tyre through technical corners and rougher chutes.

My only concern is that the suspension may be a little too active for some riders. Adding compression damping on the fork and shock does help to increase the platform and ride height, but riders who normally favour a much firmer and snappier suspension feel may find the Fuel EX a little too plush and controlled.

Trek Fuel EX 9.7
Stamping on the pedals out of corners, the RE:aktiv shock tightens up to give you plenty of support. Photo: James Vincent.

Durability

Throughout the test period I have had constant issues with the return of the dropper post. When you push the lever through its travel, the lag on the post returning has been incredibly inconsistent. On more than one occasion I have had to reach back and manually pull the saddle and seat post up the remaining 30% or so of its travel. This has been super annoying, especially on sharper climbs when having that immediate return is a must.

Unfortunately, this is consistent with our previous experience testing this post design on other Trek bikes, and you’ll read similar results in Tom’s standalone review of the Drop Line post.

The issue seems to mostly be related to cold and wet riding conditions, which cause the dropper to feel overly sluggish and sticky. Regular rebuilding will help to return proper function, but hopefully Trek can resolve this issue, as it’s been a real downer on this bike.

That aside, I have noticed some creaking coming from around the bottom bracket and headset in our test bike. This has become quite audible towards the back end of the test period of three months, and I suspect it’s time for a few things to be pulled apart, cleaned and greased up.

Trek Fuel EX 9.7
A few harsh impacts, resulting in a puncture may have also caused this slight ding. Sorry Trek.
Trek Fuel EX 9.7
There are plenty of neat frame features on the Fuel including Treks Control Freak internal cable routing system.

Three Things That Could Be Improved

  1. A wider stock bar to give more control at high speed
  2. Intricate internal cable routing is tidy, but more of a maintenance headache
  3. Dropper post sticking issues throughout the test were super annoying

Three Things I Loved

  1. It’s fast. Like really fast. When you let off the brakes this bike rips
  2. The build kit is pretty much faultless. A very considered spec
  3. It’s one damn good looking bike. Like a smaller Slash, the aesthetics are so clean and crisp
Trek Fuel EX 9.7
Pleasing aesthetics all round.

Overall

Even though the frame design is three years old, the Fuel EX is still a top performer in this category, and this model has got to be on the list for riders who are after a do-it-all bike. Everything does its job and once you take a bit of time to set up the suspension and get it dialled, this bike rips hard. A trail bike indeed, but with the ability to keep even the most aggressive rider happy.

If you want to rip round trail centres, or slam down steep technical natural trials, the Fuel EX will very happily go where you want it to. If you’re wanting a bike for racing, the larger travel Slash would be the next option, but for a bike to live with everyday there’s nothing much to argue with here. For the cash, this bike offers a hell of a lot of performance.

2019 Trek Fuel EX 9.7 Specifications

  • Frame // OCLV Mountain Carbon main frame, alloy stays. 130mm Travel
  • Fork // Fox Rhythm 34 Float, GRIP adjustable damper, 130mm Travel
  • Shock // Fox Performance Float EVOL, RE:aktiv 3-Position Damper, 210×52.5mm
  • Wheels // Bontrager Line Comp 30, Tubeless Ready, 54T Rapid Drive, Boost 110 Front & 148 Rear
  • Tyres // Bontrager XR4 Team Issue, Tubeless Ready, 29×2.40˝
  • Chainset // Truvativ Descendant 6k Eagle DUB, 32T Direct Mount
  • Rear Mech // SRAM GX Eagle, 12-speed
  • Shifter // SRAM NX Eagle, 12-Speed
  • Cassette // SRAM XG-1230 Eagle, 11-50, 12-speed
  • Brakes // Shimano Deore M6000, 180mm rotors front and rear
  • Bar // Bontrager Line 35, 15mm rise, 750mm width
  • Stem // Bontrager Line 35, Knock Block, 60mm Length
  • Grips // Bontrager XR Trail Elite
  • Seatpost // Bontrager Line, 150mm Travel
  • Saddle // Bontrager Arvada
  • Size Tested // 21.5
  • Sizes available // 15.5, 17.5, 18.5, 19.5, 21.5
  • Confirmed Weight (with updated cockpit) // 13.9kg (30.8lbs)
  • RRP // £3,150.00

Review Info

Brand: Trek Bikes
Product: Fuel EX 9.7
From: Trek, trekbikes.com
Price: £3,150
Tested: by Rob Mitchell for 3 months

Comments (3)

    Active Breaking Pivot (ABP)???? Shouldn’t that Active Braking Pivot?

    How can you say that both the bar/stem combo, and the dropper are shortcomings, and then say that the build kit is faultless? Sorry, but this is a poorly written review with too much waffle and too many inconsistencies; it is not up to the usual Singletrack standard… 🙁

    While not limited to just this review, it does seem wrong to review a bike using parts it doesn’t come with.
    The main review should be about what you get in the box.
    Maybe add a bit at the end on what could be changed and the effect it has.

Leave Reply