The Trek Fuel EX 5 presents a high quality frame that falls victim to economising.
- Trek’s solid, high-quality alloy frame and Full Floater design make the Fuel ripe for upgrading
- Sealed bearings on the magnesium EVO link ensures 120mm of buttery smooth suspension
- Trek’s rear triangle has a Boost 148 sticker, but the budget doesn’t stretch to a wider hub and stiffer rear wheel
- SRAM X5 shifters and GX rear mech gave haphazard shifting
Trek’s Fuel EX is one of the most successful mountain bikes around, reflected by a whopping range complete with eight unique models spanning both 27.5in and 29er wheel sizes.
Trek also offers a far broader choice of sizes than most, meaning it’s much easier to achieve the perfect bike fit. And because the top tube on the Fuel EX is really low-slung, it’s easy to upsize and fit a shorter stem, which is exactly what we did.
As one of the brands still giving equal billing to 29in wheels, Trek’s higher grade Alpha Platinum alloy frame on the latest Fuel EX 29 feels solid and tight, yet also very lively. With flowing lines and a sculpted, lightweight, magnesium rocker link (to keep suspension silky smooth and improve frame stiffness) it looks great too. Neat features abound, and include a thick, rubberised down tube guard and chainstay protector to quieten any chainslap.
Dive deeper into the tech and the Fuel EX is dripping in proprietary innovations, such as Trek’s ABP (Active Brake Pivot) suspension, which improves traction and control by helping the rear suspension remain active when rear wheel braking.
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The Monarch RL shock isn’t a custom Trek unit, as fitted to more expensive models, but still offers great levels of grip and support. The bike pedals efficiently, but always feels pretty plush, and there’s a lockout on the shock too.
The hyperactive, coil-sprung RockShox fork can’t keep up with the rear, however. Our size 19.5in test bike came with a firm spring as standard, but it still felt too soft, even for lighter riders. The damping is sub-par, too, and rapidly upsets rider balance when the trails gets rough.
It also gets a crude rebound lever, which makes it harder to dial in an accurate damping setting to match the back end, which further undermines the Fuel’s harmony.
Too many disappointing, cheap parts contribute to the Fuel EX being heavy and temperamental. The SRAM gears delivered frequent slips and ghost shifts and, combined with flexy Race Face cranks and a freehub that’s slow to engage, meant power delivery was so patchy that we soon gave up on hard pedalling efforts.
Our enthusiasm for the Fuel EX was further dampened by the heavy, own-brand wheels (5kg with tyres, rotors and cassette).
They were slow to build speed, which isn’t the best recipe to excel in a UK winter, even if the XR3 tyres have a decent rubber compound and casing. Also, Trek really needs to design a rear QR ABP axle that doesn’t stick out so far from the dropout — scuffs and scrapes in the anodizing prove it frequently catches while riding.
Trek’s frame geometry and sizing put you in a stable position that maximises flow once you’re up to speed. The rear suspension melds with the bigger hoops to give real smoothness over rough terrain too, meaning the 120mm travel on offer feels plenty for most UK trail riding.
There’s excellent braking control, and pedalling doesn’t cause excessive feedback, but the bike’s weight means it’s a slog to accelerate out of corners, or crank up the tempo on flatter terrain. Some heavy bikes ride light… the Fuel EX 5 isn’t one of them.
The Fuel EX steers very lightly. This can be sweet on technical, switchback climbs, but on rapid descents the front tyre skims the ground, dances over damp roots, and feels nervous in fast turns. In fact, despite the sorted ABP rear end, testers never felt planted enough to lean hard on the front and commit to sudden direction changes.
The Fuel’s 32lb weight could be vindicated if its descending prowess was extraordinary. But it’s not. And with the under-sprung fork — that pitches your weight forward — it never encourages the kind of flat-out blasting the frame is obviously capable of.
The Trek’s aluminium frame is high quality, offering well-tuned 120mm suspension and oodles of potential to upgrade. However, this cheapest model has a parts package that’s a major victim of economising and it simply can’t keep pace as a result. The coil-sprung Recon fork is the main culprit. It’s divey and de-stabilising, which erodes the Trek’s overall surefootedness. So, while we appreciate some riders might like the reactive speed of the handling, sluggish wheels and poorly functioning drivetrain really throw a wet blanket over the Fuel’s potential to ignite.