The Trek Fuel EX is one of the best trail bikes I've tested, but the new version might be even better

The typical three-year life cycle of a mountain bike model has now passed for the Trek Fuel EX, with the Wisconsin-based brand resigning what was a great trail bike to the past, in favour of a new, broader Fuel and Fuel+ family, with even more bells and whistles.

The previous Fuel EX 8 Gen 6 scored a strong 4 stars when I tested it in 2023, with only poor Bontrager tyres and a harsh cockpit letting it down.

However, the chassis was fantastic.

Trek managed to distill what I felt was ideal trail bike geometry into its 140mm machine, and added more than a sprinkling of useful adjustability.

Headset cups, Mino Link chips, mullet capabilities and an adjustable suspension chip all offered usable and useful alterations to how the bike felt on the trail.

It was a bike that less experienced riders could jump on and progress at speed, while more advanced riders could tune it to their heart's content – especially with an upgrade to a set of the best mountain bike tyres.

Although that bike is sadly departing the range, I feel its replacement takes the winning formula and gives it even more oomph.

Fuel EX is now Fuel EX, Fuel MX and Fuel LX

Trek now positions the Fuel family as a trio of bikes, all of which share the same alloy or carbon frame, but offer different propositions.

Via swappable links, chips, wheels and forks, Trek has an option for those looking for a shorter-travel ‘traditional’ trail bike all the way up to, in essence, a mini enduro bike, without the high-pivot shenanigans of its long-travel Slash.

In addition, there’s an electrically assisted version of each bike, the Fuel+ family, which features the mid-power, low-weight TQ HPR60 motor.

The shortest bike is the Fuel EX (or Fuel+ EX). This comes with 145mm of travel at the rear, along with 29in wheels. Those looking at longer days out and potentially less gnarly trails might like this one.

In the middle is the Fuel MX (or Fuel+ MX), with 150mm of rear travel and mullet wheels – 27.5in at the back and 29in at the front. Playful, poppy, aggressive and potentially shorter riders might pick this option.

At the longest end of the spectrum is the Fuel LX (yep, you guessed it, and the Fuel+ LX), with 160mm of travel and large-diameter wheels. Big hits and gnarly lines are the bread and butter here, with climbing efficiency less important.

Chipping and changing

In theory, if you purchase one of these Fuel bikes, you could adjust it to any other.

There’s an MX rocker and lower shock mount to turn the Fuel EX into the MX – you’ll need to swap out the rear wheel and add a 160mm fork air spring, too.

Should you wish to turn it into the long-travel version, there’s an LX rocker link to chuck on, although you’ll need a longer 170mm fork and a longer-stroke shock to boot. It’s all possible, though.

In addition to the ability to shift wheel size and travel, Trek has retained the leverage-rate adjust chip at the bottom of the shock.

This alters the bike between a less progressive setting – easier to use the travel and ideal for air shocks – and a more progressive setting that's better for big hits and usable with coil shocks.

In a move away from Trek's ‘own’ standards, there’s now a Zero Stack (56/49) internal headset as standard. This type of headset has numerous aftermarket alternatives, offering angle adjustment and custom colours.

Other notable frame features include long, straight seat tubes to enable the use of long-drop dropper posts, updated internal frame storage and a chainstay guard, and a 200g lighter frame with slightly modernised geometry.

This modernised geometry sees stack heights growing more proportionally with reaches, and the size range shrinking to five, rather than eight options.

The smallest XS bike will come with mullet wheels, regardless of model, although shorter riders who still want a 29in rear wheel can fit one.

With all the options on wheel size, frame adjustability and assistance level, we won't show all six geometry charts here.

Below is the carbon Fuel MX's geometry (the alloy is slightly different). The EX is a touch steeper and longer, the LX slacker and shorter.

Fuel+ geometries are almost identical.

Let’s add power

The Fuel+ features are all very much the same, however there’s a TQ HPR60 motor down by the bottom bracket, and a larger 580Wh removable battery in the down tube.

The updated motor has 60Nm of torque, 350W of maximum power and gives up to 200% support.

The power is delivered at much lower cadences than the outgoing HPR50 found on the previous Fuel EXe, which should make it feel better on the trail. In addition, it’s said to be an incredibly quiet motor, which will suit those who like a stealthy ride.

Trek says the HPR60 motor, with the 580Wh battery, should give a range of 81km – up from 36km on the previous assisted Fuel EX.

What’s on offer?

With two frame materials, three sub-families, assisted and non-assisted options and the re-introduction of Trek’s Project One programme, which offers colour and spec customisation, there are many configurations and prices on offer.

Excluding Project One options, a quick scan of the model price list suggests there are 41 models across assisted and non-assisted bikes.

As such, we won’t go into detail here – head to Trek’s website for all the model information.

Prices start at £2,200 / $2,899 / €2,499 for an alloy Fuel EX 5 and £4,400 / $5,999.99 / €4,999 for an alloy Fuel+ EX5.

Of note, is the use of Maxxis tyres on the higher-range models. The Bontrager rubber fitted to my test bike in 2023 was a sticking point, so it’s great to see this addressed.

If you’re picky about your parts, a Project One build might be worth checking out, with Trek enabling you to select parts including suspension, drivetrain, brakes, tyres, wheels and more.