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Trek Fuel EX 8 review – still one of the best trail MTBs?

Trek’s alloy Fuel EX trail mountain bike lacks the latest features but is the overall package still a winner?

Trek Fuel EX 8
(Image: © GuyKesTV)

Bike Perfect Verdict

Heavy frame that misses the latest features but still a great package for fast and precise all round mountain biking

Pros

  • +

    Tight, precise frame

  • +

    Sorted all round handling

  • +

    Very efficient suspension feel

  • +

    Durable Shimano kit

  • +

    Excellent sizing options

Cons

  • -

    Heavy frame

  • -

    No internal storage

  • -

    Press fit bottom bracket

  • -

    Top Fuel is more playful

Trek’s Fuel EX has been one of the best mountain bikes in the world for years, but the alloy-framed 8 is lacking some of the features the latest alloy and carbon Treks. High-durability component spec matches the vibe of a really well-balanced bike. One that plans ahead, hands its homework in early (having double checked it) and rarely puts a wheel wrong or goads you into being silly yourself. So how has Trek done that and is there a better option in the range if you want something short on travel but big on fun?

Trek Fuel suspension

Trek are sticking with their tried and tested rocker linkage layout (though Turner used it way before any Session did) (Image credit: GuyKesTV)

Design and aesthetics

Trek has been using a rocker link-driven, vertical shock suspension design on its bikes for so long that “Looks like a Trek Session” is a cliche on most MTB forums. No surprise then that the Fuel EX continues the clean looks which leave plenty of room for a big bottle on the down tube and strap-on storage. You don’t get the internal storage of the newer Top Fuel alloy frame though and this older frame still uses a press-fit bottom bracket rather than reverting to a more reliable threaded  format. There are ISCG chain keeper tabs on the BB though, a wider-angle Knock Block steering limiter to stop bars hitting the frame in a crash and rear axle concentric ABP rear suspension pivot. Cunning zip tie tabbed ‘Control Freak’ internal cable routing and rubber frame armor including molded chainstay sleeves keep things quiet. 

You also get the 0.5-degree geometry change ‘Mino Link’ flip chip at the seat stay/rocker pivot. That changes head angle from 65.5- to 65-degrees and effective seat angle from 75.5- to 75-degrees on the Large I tested. Reach also shifts from 475 to 470mm and BB height drops from 346 to 340mm. The big win with choosing a Trek though is the sheer range of sizes from XXS to XXL including a sweet spot ML in the centre. Smaller bikes also run 27.5in wheels for proportional balance, too, although the chainstays are the same length on all frame sizes. The Fuel EX 8 is also available in three different two-tone color options.

Shimano XT drivetrain on Trek Fuel EX 8

An almost complete Shimano XT drivetrain is a durability highlight on the EX8  (Image credit: GuyKesTV)

Specification

Trek acknowledges that the ‘priority is on the parts’ with the EX 8 and the highlight is an almost complete Shimano XT drivetrain (the chain is SLX). The Fox Float shock is a custom unit, too, using a Penske race car derived RE:aktiv damper setup for a pert-pedaling feel on top of the 130mm travel. The 140mm Fox 34 fork is the stock Rhythm spec though and the Shimano brakes are basic four-piston MT400s. Bontrager’s functional Line component range completes the bike in well-judged, size-specific cockpit options although dropper post strokes are short on the larger sizes. Big volume versions of Bontrager’s XR5 and XR4 tires on Bontrager Line Comp 30mm internal rims put plenty of air between bike and trail for protection, too.

Trek Fuel EX 8 3/4

Tons of sizes and three color options back up a ride that's as sorted and clean as it looks (Image credit: GuyKestTV)

Performance

While the EX8 isn’t light at just under 15kg (a full kilo heavier than Trek claims) it’s in the ballpark for a mid-travel, alloy-framed bike at this price. What really stands out is how well it hides that weight when it comes to pedaling. The big tires don’t drag nearly as much as they look like they might, while the RE:aktiv shock and overall kinematic give it a really clean, crisp and stable platform to put down power from. That means even with three potential low-compression settings to play with, we rarely felt compelled to flick it out of full open unless we were hoofing uphill out of the saddle. Add the clean shifting, top-quality Shimano XT drivetrain and the Fuel EX is a great choice for high-mileage rides and riders. The fast-engaging ‘Rapid Drive’ freehub and relatively high ground clearance are a bonus for anyone who likes to kick hard out of corners or attack rough technical climbs, too. The efficient suspension feel still gives enough sensitivity to track the ground under power and you can drop pressures in the big tires if you’re into a proper ‘crawler/swamper’ feel. 

The 140mm fork/130mm rear travel feels well balanced on the trail and the Grip damper Fox Rhythm repeatedly proved why its our favorite cost-effective fork. Trek’s suspension calculator is accurate enough to get most people sorted on set-up for most situations. The angles and proportions of the model we tested were confident at speed on jumps but still turned in promptly on woodland twisters. Even the basic Shimano brakes feel better than normal through the neutral suspension responses created by the ABP pivot and the 200mm rotor up front boosts power, too.

While you could speed up reactions with a shorter stem, the stock setup probably suits its overall character better. That’s because while it will pop and play off trailside opportunities if you’re in the mood, it does tend to sit on top of an already relatively high ride height rather than sucking down onto the trail and railing. Interestingly that’s a big - and counter intuitive - difference to the Top Fuel 8. With slightly steeper angles, less travel, significantly different suspension kinematic and top-spec RockShox rear shock, Trek’s pocket rocket has an addictively playful charisma that’s very much at odds with it’s ‘XC’ categorization. 

In fact, despite it being heavier we’d probably opt for the Fuel EX for long marathon-style or efficiency-based events, especially as it’s significantly cheaper than its little brother, leaving you more cash for race entries and energy products. Just make sure you keep an eye on the press-fit bottom bracket and get it replaced as soon as it shows any signs of wobble/creak as that can eventually creates frame issues.

Verdict

Trek’s Fuel range might be a bit backwards when it comes to assigning categories based on travel but the main thing is that the Fuel EX is still a really efficient, enjoyable and fitness/skill flattering all rounder. While it misses out on the internal storage, threaded BB and super-plush playfulness of the Top Fuel, Shimano XT will always bring a lot of hard riding boys (and girls) to the yard. Those are exactly the riders who’ll appreciate just how well this extremely well balanced bike covers ground and keeps a fresh and sharp feel long into the day, and down tough technical sections, too. 

Tech Specs: Trek Fuel EX 8 XT

  • Price: $3,929.99 / £3,200
  • Discipline: Trail
  • Head angle: 66/66.5-degrees
  • Frame material: Trek Alpha Platinum Aluminum
  • Sizes: XS, S, M, M/L, L (tested) XL, XXL
  • Weight: 14.9kg
  • Wheel size: 29 x 2.3in
  • Suspension (front/rear): Fox Rhythm 34, Float EVOL 140mm travel, 44mm offset/Fox Performance Float EVOL, 3-position RE:aktiv 130mm travel
  • Components: Shimano XT 10-51T, 12-speed gearing, shifter, chainset and cassette. Shimano SLX chain. Shimano MT400 brakes with 200/180mm rotors. Bontrager XR4 Team Issue 29 x 2.6in front and Bontrager XR5 Team Issue 29 x 2.5in rear tires on Bontrager Line Comp 30 wheels. Bontrager Line 780 x 35mm bar and 50 x 35 mm stem, Bontrager Line Dropper 150mm dropper post, Bontrager Arvada saddle

Guy Kesteven is Bike Perfect and Cyclingnews’ contributing tech editor. Hatched in Yorkshire he's been hardened by riding round it in all weathers since he was a kid. He spent a few years working in bike shops and warehouses before starting writing and testing for bike mags in 1996. Since then he’s written several million words about several thousand test bikes and a ridiculous amount of riding gear. To make sure he rarely sleeps and to fund his custom tandem habit, he’s also penned a handful of bike-related books and talks to a GoPro for YouTube, too.


Rides: Pace RC295, Cotic FlareMax, Specialized Chisel, Vielo V+1 gravel bike, Nicolai FS Enduro, Landescape custom gravel tandem

Height: 180cm

Weight: 69kg

With contributions from