11 months of fueling the fire.

Trek launched the latest version of the Top Fuel nearly a year ago, in July of 2024. I got on that bike a little before launch, and since then, have been riding it on and off in a fairly wide variety of permutations. So this is part long-term checkup, and part manifesto about the Top Fuel, and other bikes of its ilk.

Trek Top Fuel Details

• Travel: 120 mm (rear) 140 mm (front)
• Wheel Size: 29” with MX capabilities
• Size Tested: Large
• Build Tested: Frame Only
• Head Tube Angle: 65.5°

As a quick refresher, the Top Fuel is Trek’s second-lightest full-suspension bike. When it was launched, the brand was very clear that it wasn’t a trail-ified cross-country race bike. The product presentation was explicitly not “look how much lighter and more efficient we made this thing.” Trek went out of its way to make it clear that the Top Fuel is no Specialized Epic Evo, no Santa Cruz Blur Trail. The company hedged that sure, its World Cup team could reach for the Top Fuel for more technical tracks if they wanted to, but that wasn’t the point of the bike.

And then, yes, Trek’s World Cup athletes have been reaching for the Top Fuel (or a bike that looks an awful lot like one) pretty regularly. It turns out the bike has that range. But primarily, in my experience, the Top Fuel does two things really well: it delivers a capable, adaptable platform that can handle a wide range of riding, and it presents the most compelling e-bike alternative I’ve ridden.

But before we dive in, check out Spencer’s take from last year.

While I initially rode the same 9.9 XX AXS build that Spencer reviewed, I’ve spent most of my time on various bastardized frame-up builds of the Top Fuel. I raced cyclocross (poorly) with a 120-millimeter fork, race slicks, and a seven-speed downhill drivetrain. I went on big wandering exploratory rides with downhill brakes, meaty tires, and an old ten-speed Shimano drivetrain. And now, I’m running a do-it-all build centered around SRAM’s spring releases. 

I’m using the SRAM Eagle 90 mechanical drivetrain, and even with the advent of new XTR, I think the Eagle 90 derailleur and shifter, combined with a higher-end cassette is my dream drivetrain. I’d rather eliminate b-tension and limit screws than cables. 

I ran SRAM’s Motive brakes on the Top Fuel for a few months, and they’re a great match for this style of bike. They’re notably more powerful and all-round better than Levels. That said, the Motives are on their way to a slightly longer-travel bike, and I’m back to running Hayes Dominions on the Top Fuel. Overkill is underrated.

I’ve been running a set of Forge+Bond wheels, but am about to swap on a review set of Hunt Proven review wheels, shod with a Schwalbe Tacky Chan out front, and a Specialized Ground Control on the rear.

In terms of suspension, I’ve been bouncing between a Fox 36 SL (review soon) and a RockShox Pike Ultimate, both set to 140 millimeters of travel. The seat is suspended on a RockShox Reverb AXS dropper, and I've been enjoying BikeYoke's 3D printed saddle.

That’s my preferred build, but the magic of the Top Fuel is its range, so let's get into it.

Choose Your Own Adventure

Trek did two things that, in my opinion, set the Top Fuel up to be an adaptable platform: It didn’t try to make it into a super-light cross-country whip, and it included a four-way Mino Link at the lower shock mount. 

I am a large man (200 pounds) who likes to make poor decisions on steep, fast trails. I’ve spent my fair share of time worrying that I’m about to break lightweight 120-millimeter flex-stay bikes because I’m riding them outside of their intended use case. The Top Fuel never feels like that. The frame is impressively stiff, and wiggle-free without ever feeling harsh. That gives me the confidence to push it harder.

And when you push the Top Fuel harder, the suspension platform rises to that challenge.

We keep talking about how bikes in this travel class “punch higher than their weight” or “out-descent their numbers.” The Top Fuel breaks that paradigm. I don’t feel like I’m “getting away with it” on this bike. It doesn’t have the scary frame flex, or weird suspension bobbles that usually indicate that a bike is doing its damnedest, but it’s outside its comfort zone. Instead, it makes me think that the general expectations for a lightweight bike in this travel range have shifted.

It’s not that the Top Fuel outperforms its numbers. Instead, the Top Fuel says “this is how bikes with these sorts of numbers can and should descend.” It moves the bar. The little bit of extra beef that the Top Fuel carries goes a long way toward it feeling like a “real” bike, not a tiny cross-country whip.

That, combined with the flip chip that lets you adjust both the progressivity and geometry means that you can stand the bike up into being a fairly steep cross-country bike, or slack it out for meaner terrain. The flip chip also takes up enough geometry slack that you can run it with a 27.5-inch rear wheel, which transforms it into a dual-slalom-slaying party machine.

I’ve spent a bunch of time in each of the four flip chip settings, and haven’t found a “best.” Instead, I’ve found myself swapping between them, depending on the needs of the day. It’s a fast and smooth transition, that’s easy to do in the parking lot while your companions pull up their kneepads. Yes, it adds weight, and I think that’s absolutely worth it on a bike like this. Get as weird as you want. Looking for a 120-millimeter bike with a mullet and a coil shock? The Top Fuel has your back.

The Freedom E-bike Ads Promise

One of my favorite saws states that “Bikes deliver the freedom car advertisements promise.” I agree, and I’d add that bikes like the Top Fuel deliver the freedom that e-bike ads promise. My inbox is full of marketing copy promising that a motorized bike is “me but better,” that it will allow me to “explore further,” and generally deliver an “elevated” mountain bike experience. And I’ll continue to die on the hill that adding a motor to a fundamentally non-motorized vehicle doesn’t elevate it, it changes it into another, different, also fun, but again, separate form of recreation.

But taking a bunch of weight off the bike, while still keeping all the things that make it fun to eat big miles and charge challenging descents? That makes me feel like myself, but better. And that’s what the Top Fuel does.

All of the arguments that folks use to justify e-bikes work just as well for the Top Fuel. It allows you to grab a quick lunch lap from your busy schedule. It allows you to go further in the same amount of time. It motivates you to ride when you’re tired, or it’s too hot, or whatever other excuse the world throws at you. It’s “still totally the same workout as riding a real bike.” It amplifies the mountain bike experience without compromising it into something else.

And to be clear, this isn’t something that’s totally unique to the Top Fuel. It’s just that this bike does it really well. There are plenty of cross-country bikes that make me feel like I’m climbing with a pedal assist, but most of them don’t go downhill like this.

The Top Fuel also alleviates many of the frustrations of e-bikes. It’s easy to lift over downed trees. I don’t get a hernia putting it in the truck. I can ride it on non-motorized trails. It won’t be outdated when the next evolutionary leap in motor technology comes. It creates no e-waste. I never have to worry about charging the battery. 

E-bikes sing their siren song of whining motors and beeping controllers, but the Trek Top Fuel has me solidly tied to the mast, bee’s wax in my ears, and a smile on my face. This motor runs on Uncrustables and Mountain Dew.

Learn more: Trek Bikes