Riders have never had more choice when it comes to trail bikes, and there is a different geometry profile, suspension setup and wheelset combination to suit every type of terrain and preferred riding style.
But all that choice can be an issue, particularly if you buy into a specific, specialised design that can’t easily be adapted to the task at hand.
Trek understands this, which is why it has gone big on versatility with its latest generation of the Fuel.
“We realise there's a lot of different riders in the trail segment that do everything from their mediocre cross-country trail to pretty much an all-mountain enduro-style of riding,” says Dave Knauf, Trek’s full-suspension product manager.
Rather than simply updating its gen 6 Fuel EX – an aggressive design with a 150mm fork, 140mm rear-wheel travel, 29in wheels, and geometry-altering flip chip, headset options and mullet compatibility – it set out to broaden what the platform could do and meet the wide-ranging needs of various riders.
The result is a range that features one frame across three stock builds – the Fuel EX, Fuel MX and Fuel LX – that cater to everything from trail taming to all-out enduro.
But the possibilities don’t end there.
Thanks to two lower shock mounts and three rocker links, that same stock Fuel frame can be adjusted to fit your style, with Knauf adding that they “allow us to adjust the geometry and kinematics on the frame to get to bikes that we previously would have built in three separate platforms”.
This means that, with a little bit of tweaking and part swapping, a bike that’s at home on your mellow local trails can tame the gnarliest Alpine bike-park descents.
But how did Trek settle on this adaptable approach? Knauf and Trek’s senior mountain bike engineer, Dylan Howes, reveal all…
Rider-led reasoning
If you include ebikes, Trek has 17 different mountain bike platforms – ranging from the Marlin cross-country hardtail through to the UCI World Cup-winning Session downhill rig.
Seven of these alone fall under its full-suspension trail bike offering, so embarking on a project such as the latest-generation Fuel needs a clear driving force from the off.
“This started out as an R&D project,” says Howes.
“A handful of us were like, ‘Man, I miss the Remedy. Could we get a Remedy back? Could we do this with one frame?’.
“You start designing and constraining, going ‘if we could just change this part and maybe this part, you get two options, and then from there, if I change this again, I could get a third one. At one point, we were actually up to five different options.
“It's one of those things that starts simple and grows in complexity. It would be very hard to start out doing this – this one just evolved into what it is.”
While the modular system is a first for consumers, the team had prior experience with custom links and lower shock mounts through its factory race teams, with the Fuel benefitting from trickle-down tech previously reserved for the pros.
“This concept is following things we've done with race teams – configuring their bikes to get them something just a little more or a little different than what was stock,” adds Howes. “At some point, you go, ‘if [the pros] like this, there are going to be discerning customers who like this'.”
Combine with compromise
The design processes for the latest-generation Fuel started towards the end of 2023, with Trek’s production team given just under two years for it to be ready and in store. But the team weren’t coming to the project cold, with the ideation process decades in the making.
“Dylan's been ideating for 20 plus years,” laughs Knauf. “It's the evolution of the EX, and then challenging Dylan and the team to take the other platforms that we also know work really well and try to combine them, but not compromise or lose those special attributes that make those bikes what they are.”
“We know we're going to update [the Fuel] every three to four years,” explains Howes, and with a deadline of July 2025 to hit, the schedule only allowed for a finite amount of R&D and production time before decisions have to be finalised.
“I think you always leave stuff on the table because of that. The good ideas are the ones that stick in your head. You're like, ‘alright, next one’. We could keep iterating for years to get to perfect, but we've got something really good.”
“Dylan and team are always continuing,” adds Knauf. “We have the next EX and concepts of that are already sitting in the office. We always want to understand what else we could do. But at some point, we’ve got to understand this is where we're at and we can save that for the next one.”
Crafting for compatibility
As well as featuring a modular system, the Fuel is one of two mountain bike platforms (including the Supercaliber) where higher-end models can be built to your custom spec courtesy of Trek’s Project One programme. This enables riders to cherry-pick components from a range of brands across everything from groupsets to grips, and swap out an air shock for a coil alternative.
But Trek didn’t limit the Fuel’s compatibility to the componentry it offers through Project One.
“We try to be cognisant of all the other stuff out there because there are a lot of riders that want to tweak their bikes,” says Knauf.
“Designing all this into a bike and making sure there aren't any catastrophic failures or really bad things that you can do with it is challenging. There's the space constraints there, and planning for that definitely takes some effort.”
“We're always looking at how we make sure there's the most room we can fit around the shock,” adds Howes. “A customer is going to ask ‘can I fit this new EXT shock or push shock?’.
“As good as those shocks are, they're from smaller companies, so we're not going to be able to spec them. The art is trying to design in as much clearance and as many options as you can, and ultimately that helps us.”
Acoustic and electric in tune
The new modular Fuel platform is mirrored in the Fuel+ ebike offering, which also benefits from the 'one frame, three bikes' concept.
Trek managed this by designing the chassis in tandem, and sharing as much of the same DNA as possible between the non-assisted and electric offerings.
“The previous Fuel EX and Fuel EXE look very similar, but the rocker links and seatstays were different, and there was some different hardware in spots,” says Howes.
“On this one, there were two of us as the lead engineers – I was working on the acoustic, Matt [Yerke] was sitting next to me working on the Fuel+, and we kept going together with this goal of sharing.
“At some point, you get into little things like ‘we’ve got to move this shock just a couple millimetres so it works with both’, but those are the production details you get into.”
The Fuel+ was also able to share a lot of the same properties as the Fuel because of Trek’s new mid-power TQ HPR 60 motor.
“Of all the different new systems out there, it has the least impact on the overall design,” adds Knauf.
“Generally, we're starting with acoustic platforms in terms of geometry and kinematics, and then understanding what we love about those bikes, and trying to achieve that within an e-bike, where there's generally some compromise.
“The awesome part in the original EXE, and now this Fuel+, is that we really don't have to compromise those pivot points. The motor and battery are so small and compact, it feels like the acoustic bike.”
