The Quiet Overachiever: The 2025 Trek Top Fuel

Abandonment of Ego

This isn’t so much a wrap-up as it is a mid-test chin wag.

I had high hopes of some eventual profound revelation during my time aboard Trek’s latest twist of the venerable Top Fuel saga; that the bike would unlock my inner Superman, or that I would discover some incredibly damning character flaw in the bike and be able to emphatically state that there were far better choices out there for people looking for a 120/130mm “all world” mountain bike.

But my inner Superman never surfaced. And I can’t really think of many bikes that manage 120mm of rear travel with such businesslike capability. I can’t fault the Top Fuel for not turning me into a better rider. That’s on me. And it is unfair to wish that there was some sharpness of character, some brutality of intent, some rowdy edginess that this otherwise understated bike exhibited while quietly and efficiently bagging thousands of feet of climbing and hundreds of miles of singletrack. I mean, do bikes really have character anyway, or is that all just part of the wordy hyperbole that marketing departments and journalists come up with to try and craft differentiation when splitting metaphorical hairs between very similarly designed, very similarly capable bikes?

For the record, the Top Fuel is an excellent bike. I had some absolute peak experiences aboard it this summer, and never once needed to take a wrench to the pivots or chase down errant creaks and rattles, and it got the job done without a hint of trouble everywhere from heat stifled sand washes to hypoxic ribbons of singletrack far above timerline. But when there is a lack of things to complain about, when the desire to fiddle and modify and adjust is close to zero, this can make for a pretty boring bike review. TL/DR; it works, you’ll like it, well done.

Unsurprising Excellence

To recap, this 7,000 USD Top Fuel 9.8 GX AXS arrived back in July, and was given a first look then slotted in amongst some other bikes of rowdier intent. The miles began to add up. The options for adjustability were explored, some minor tweaks were made here and there, but ultimately this stealthy little rig just got ridden, and ridden, and ridden some more.

Trek’s efforts to broaden the Top Fuel’s appeal and capability paid off. They took a bike with an exceptional “pedal all day” pedigree, retained that superb ease of pedaling and climbing, and managed to balance heaps of tractability and maneuverability with just enough chunk and chunder munching ability that this can legitimately be viewed as a natural evolution of cross country into trail riding. Compared to other 120mm travel bikes, it is right in there with the Yeti SB120 and the until-recently Horst-Linked Rocky Mountain Element, in terms of blending pedaling efficiency with XC-plus trail manners. As with those other stellar lightweight all-rounders, the Top Fuel sacrifices some accelerative edge to the current crop of flex-stay XC race bikes, and all the way at the other end of the spectrum begins to show its limitations when the going gets really steep and really rough. But it’s otherwise a superb bike for 90% of the trails on this planet.

The Top Fuel’s 4-position flip-chip allows some geometry steepening and sharpening, as well as some ramping of the rear shock. After futzing with all four positions, I opted to leave things in the slackest, lowest and least progressive of the four settings. 30% sag, middle of the road low speed compression, and as the saying goes, Bob’s your uncle (but no real pedal bob to speak of). This offered what felt like the most predictable and surefooted stability at speed while still maintaining excellent climbing manners. Going steeper and higher helped slightly in techy climbs but made things more nervous in general. Adding more progression felt like it helped a teeny bit with what was already pretty damn good pedaling behavior, but not enough to justify less plush mid-stroke comfort. So, really, all I did after that initial futzing around was maintain 25psi of air in the tires, try to remember to keep the damn derailleur battery charged, and ride.

The word that keeps coming to mind when trying to define this latest Top Fuel is "cohesive." Light, but not whippy, the frame is just stiff enough for the amount of travel the bike has. The Rockshox Pike fork and Deluxe shock are really well matched to each other, and again, there's just enough progression at either end to get as rowdy as the frame and tires want to. The riding position is probably conservative by contemporary standards, with the skosh under 76 degree seat angle matched by a 65.5 degree head angle and 477mm of reach on this size L test bike, but it feels just about perfect for getting the tires to stick in corners and for pedaling hours on end. The fit and finish of everything is clean and really well thought out, from the pivot hardware to the cable routing to the shape of the grips. Everything feels balanced, there's nothing radical or weird to try and ride around or get used to, and it all feels very... cohesive.

Given that nothing at all broke, and that nothing very surprising occurred during the summer, I am going to keep this short for now and truncate this review into two parts: Things I Didn’t Like, and Things I Want To Try.

Things I Didn’t Like

Much as I am a fan of the new school stubby saddles, and in spite of initially thinking that we were going to be friends, my ass never really got onto comfortable terms with the Trek Verse Comp that came on the bike. I am willing to chalk that up to personal preference. Staying in the same neighborhood for a minute, the Bontrager Line dropper post actuated well enough, but there was enough fore and aft play that it would sometimes feel rattly on rough descents, marring what was otherwise an incredibly quiet and composed ride experience. Also, while 170mm of drop is adequate for my stumpy legs, that’s not enough for most people who ride large frame sizes these days. 180mm rotors front and rear were a sensible spec for the intent of this bike, but at high speeds and on longer descents I never really felt like the SRAM Level Bronze brakes had the kind of bite that I wanted. Maybe a swap to metallic pads would help in this regard.

I love the aesthetics of the RSL integrated bar/stem, and really loved the feel of the grips that came stock on the bike, but my hands tended to feel kinda hammered and crampy at the bottom of rough descents. These are 820mm wide bars, so it’s extra surprising that they feel so stiff. Maybe it’s just a matter of needing a few degrees of roll in one direction or another, but since experimenting with bar position is impossible, this is how it is unless I swap in a new stem and handlebar completely. Finally – the wheels. They did their job. They stayed round. But a close to 2000g wheelset with alloy rims on a $7000 carbon fiber bike is a tough pill to swallow. Especially when they are a major contributing factor to the almost 30lb weight of the bike. Given the weight of the wheels, and the bike overall, it is amazing that the Top Fuel climbs and accelerates as well as it does.

Things I Want To Try

Trek made no bones about the Top Fuel being an adaptable and versatile bike, and went so far as to send out a 185x55 RockShox Super Deluxe Ultimate to swap in. This will bump rear travel to 130mm. I’ve got a Pike air shaft here that’ll let me stretch the fork out to 140mm travel. So that’s the next order of business. I know, I know. I’ve been banging the “just ride the damn thing the way the designers intended” drum a lot this past year. But in this case, the designers were the ones who sent me the new shock to try out. So, may as well see what happens.

Next, I am gonna try and make the brakes a bit more bitey. Pads first, then more drastic measures if warranted. Ideally, I do not want to go to bigger rotors because I really don’t want to pretend this bike is something more than what it already is; an excellent all-rounder.

I have a set of wheels that I have been hoarding from one lightweight bike to the next for the past couple years. They are Roval Control SL Team LTD wheels. They weigh 1245g for the set. This is kinda cheating, but it’s cheating with a known quantity. In my mind, this particular model of Top Fuel should have come with a set of 1500-1600g wheels to begin with, and that the down-spec to the boat anchors that were on it was one of those internal budget/profit decisions that really feels like a poke in the eye. Shedding a couple pounds of rotating mass will be fun. This will wait until after the suspension gets lengthened, so that I can get an apples-to-apples read on how the extra suspension impacts the pedaling and climbing manners, if at all.

As it sits right now, I really like the Top Fuel. It sits right there neck and neck with the SB120 as one of my favorite pedal all day anywhere bikes. I want to find out if the extra suspension will make it more able to hang in the rough stuff with something like the battleship stable Transition Smuggler I just reviewed, or maybe put it into the same super-fun realm as the Mondraker Raze. And IF these changes do manage to up-category the little Trek, will they come at the expense of that wonderful pedalability? Only one way to find out...

2025 Trek Top Fuel 9.8 GX AXS