First Ride | The 2025 Trek Top Fuel gets a new frame with adaptable travel, geometry & wheelsize


The not-so-minor details

Product

2025 Trek Top Fuel Gen 4

Contact

Trek Bikes

https://www.trekbikes.com

Price

From $5,499 AUD ($8,999 AUD as tested)

Weight

13.14kg

Positives

- Snappy pedalling performance
- Active suspension delivers grip both up and downhill
- Sporty all-round handling
- Adaptable travel, geometry & wheelsize
- Practical frame design with plenty of protection & storage

Negatives

- RSL handlebars are quite stiff once cut down to a reasonable width
- SRAM Level brakes suffer from excessive dead stroke
- Not the lightest bike in its category

Overhauled for 2025, the all-new Trek Top Fuel represents the 4th generation of the platform. Having started out as a pure XC race bike, the Top Fuel has evolved over the years with a steady increase in travel that’s broadened its capability and versatility. Nowadays it slots right in between the latest Supercaliber and the Fuel EX, occupying a hazy middle ground that could be considered ‘long travel XC’ or ‘lightweight trail’, depending on your perspective.

Blurring the lines even further, the latest Top Fuel boasts more adjustability thanks to its redesigned frame and clever 4-position Mino Link. With the ability to adapt the wheelsize, geometry and suspension travel, this could very well be one of the most versatile XC bikes out there.

2025 trek top fuel 9.8 gx axs
The Trek Top Fuel has received an all-new frame for 2025.

An overview of the 2025 Trek Top Fuel

For 2025 the Trek Top Fuel receives an entirely new frame from tip-to-tail. Not that you’d really tell at first glance, with the overall shape and layout remaining much the same as the bike we reviewed back in 2021.

Look a bit closer however, and you’ll see that every tube has been slimmed down to improve compliance and reduce weight. According to Trek the new Top Fuel frame is about 100g lighter than its predecessor, coming in at a claimed 2.6kg for the carbon frame including shock.

It still isn’t super-light, but it’s worth acknowledging that unlike some of its competitors that utilise flex-stays, the Top Fuel features a genuine four-bar suspension platform. The ABP design locates the most rearward pivot concentrically to the axle, which is said to mitigate the influence of braking on the suspension. To maximise sensitivity further, the one-piece rocker link drives the trunnion-mounted shock via cartridge bearings.

2025 trek top fuel 9.8 gx axs
The rear shock is driven by a one-piece rocker link and a trunnion bearing mount.

Compared to the previous kinematic the new Top Fuel is slightly more progressive and it has a touch more anti-squat. It otherwise retains its 120mm of rear travel and it comes from the factory with a 130mm travel fork. You’ll find 29in wheels fitted to all frame sizes except the Small, which is purpose-built around 27.5in wheels front and rear.

With those kind of numbers, the Top Fuel is going up against fellow XC bikes including the Specialized Epic EVO, Scott Spark, Pivot Trail 429 and the Giant Trance 29.

New 4-way adjustability

Where things get a little more interesting with the new Trek Top Fuel is its unique 4-position Mino Link. Located at the lower shock mount, this flip chip offers a High/Low geometry setting that modifies the angles by 0.5° and changes the BB height by 6mm.

2025 trek top fuel 9.8 gx axs
The 4-position Mino Link can be flipped upside down and front-to-back, allowing you to adjust both geometry and progression.

You can also flip the chip forwards and backwards to change the suspension’s leverage rate. It comes set up in the forward position to deliver 14% progression, though orienting it rearwards will increase progression to 19% to provide more ramp-up at the end of the stroke.

Furthermore, you’re able to modify the amount of rear travel. While the Top Fuel is built around a 185x50mm shock, it’s possible to increase the stroke to 55mm and boost rear travel to 130mm.

Given the frame is rated for use with a 120-140mm travel fork, this introduces some interesting setup options. You could configure it as a lightweight XC bike with 120/120mm of travel, or as a burlier trail bike with 140/130mm of travel.

You can even set up the Top Fuel as a mullet with a 27.5in rear wheel. To keep the BB at a reasonable height, Trek recommends running the flip chip in the High position and extending the fork to 140mm of travel if you decide to go the mixed wheel route.

Refined internal storage

The new Top Fuel frame also ushers in updated downtube storage that features a larger opening. The hatch is said to have a tighter and more weatherproof seal, and the cables are tucked further out of the way to minimise snagging.

There are two new BITS bags that come with the carbon bikes; one specifically for tools and the other to carry a tube. If you’ve still got more gear to haul there’s an external accessory mount underneath the top tube.

Trek has maintained a practical approach throughout, with the Top Fuel mercifully avoiding the industry trend for routing its cables through the headset. It also ditches the Knock Block headset, but you’ll still find a good ol’ fashioned threaded BB, bolt-on downtube armour, a rubberised chainstay protector and a removable thru-axle lever.

2025 trek top fuel 9.8 gx axs
Rear travel remains at 120mm, though up-stroking the shock will allow you to increase it to 130mm.

Trek Top Fuel geometry & size chart

There have been few changes to the geometry on the new Trek Top Fuel. The 65.5° head angle is carried over, and the reach is pretty much unchanged across the five frame sizes.

The effective seat tube angle ranges from 75.2-76.9°. It’s worth pointing out that Trek lists this angle based on a specific saddle height for each size, which is great to see.

Another noteworthy update is the introduction of size-specific rear centre lengths, which vary from 435mm on the smaller frames and go up to 445mm on the X-Large.

Dropper post insertion has also improved thanks to a straightened seat tube. With the exception of the Small, each Top Fuel will come with a 170mm travel dropper post, which is fashionably long for an XC bike.

2025 Trek Top Fuel Geometry & Size Chart
The cheapest model is the Top Fuel 8, which is the only bike to feature an alloy frame.
2025 trek top fuel 9.8 gx axs
All Trek Top Fuel models come with a 130mm travel fork as standard.

Trek Top Fuel price & specs

There will be five Trek Top Fuel models coming into Australia this year. Prices will start at $5,499 AUD for the Top Fuel 8, which is the only model with an alloy frame.

All the others are built around an OCLV carbon frame and RockShox Deluxe Ultimate RCT shock. Bontrager finishing kit is used throughout, which includes a snazzy one-piece RSL cockpit and brand new Gunnison and Montrose tyres. You can see detailed specs and pricing on the full range at the bottom of this review.

The bike we have on test sits one step up from the bottom-of-the-range. It’s the Top Fuel 9.8 GX AXS, which we reckon offers the best bang-for-buck out of the lineup.

2025 trek top fuel 9.8 gx axs
The Trek Top Fuel 9.8 GX AXS bike is the second cheapest model available in Australia.

2025 Trek Top Fuel 9.8 GX AXS

  • Frame | OCLV Carbon, ABP Suspension Design, 120mm Travel
  • Fork | RockShox Pike Select+, Charger 3.1 RC2 Damper, 130mm Travel
  • Shock | RockShox Deluxe Ultimate, RCT Damper, 185x50mm
  • Wheels | Bontrager Line Comp 30, Alloy Rims, 30mm Inner Width
  • Tyres | Bontrager Gunnison RSL XT 2.4in Front & Montrose RSL XT 2.4in Rear
  • Drivetrain | SRAM GX Eagle AXS Transmission 1×12 w/30T Crankset & 10-52T Cassette
  • Brakes | SRAM Level Bronze 4-Piston
  • Bar | Bontrager RSL Integrated, Carbon, 27.5mm Rise, 820mm Width
  • Stem | Bontrager RSL Integrated, Carbon, 45mm Length
  • Seatpost | Bontrager Line Dropper, 34.9mm Diameter, Travel: 100mm (S), 170mm (M-XL)
  • Claimed Weight | 13.2kg
  • Actual Weight | 13.14kg
  • RRP | $8,999 AUD
2025 trek top fuel 9.8 gx axs
The Bontrager RSL handlebars are crazy wide at 820mm.

Sizing & fit

At 174cm tall I’ve been riding a Medium size in the Trek Top Fuel. It features a 447mm reach, which suits me just fine. Personally I wouldn’t want to go up to the M/L size, but it’s great to have that option available for riders in the 173-180cm height range who feel like they’re on the cusp between a Medium and Large.

The riding position is on the racier side, with the short head tube and near-77° seat angle pushing your weight forward and low. I haven’t found it to be uncomfortable, but it’s certainly not an upright cruiser like the Fuel EX. I can imagine that with a lightweight 120mm fork fitted up front the Top Fuel would be well suited for XC and marathon racing duties.

While the Bontrager contact points are fine, the RSL handlebar is laughably wide at 820mm. That might be ok for much taller and broader folks on an XL, but I’m not sure who else is running such wide bars on a XC bike. I promptly cut them down to my preferred width of 760mm, which effectively makes the bars stiffer by reducing the available flex. I much prefer the approach with the Race Face Era handlebars that are offered in three specific widths to avoid that issue.

2025 trek top fuel 9.8 gx axs
Trek recommends 25-30% sag for the rear shock on the new Top Fuel.

Suspension setup

To start out I went with 30% sag for the rear suspension on the Trek Top Fuel. Setup is made easy thanks to anodised gradients on the shock, and there’s also the RockShox Trailhead app for suggested pressures and rebound settings.

I’m currently running 135psi to support my 67kg riding weight and have the rebound damping on the quicker side at 7/10 clicks.

The Deluxe RCT shock incorporates a two-position lever that provides you with Open and Pedal modes. There’s also a blue three-position dial for adjusting the low-speed compression damping in the Open mode. Set it in the ‘-‘ position for a plusher feel, or dial it towards ‘+’ to firm up the rear end.

2025 trek top fuel 9.8 gx axs
The Deluxe RCT shock features a 3-position dial for tweaking the low-speed compression damping.

Having already had a fair bit of experience with the 2025 RockShox Pike and the new Charger 3.1 damper, I knew I’d need more pressure than what’s suggested in the Trailhead app. 10% extra seems to be about right, which works out to be 70psi for me. I’ve also added a Bottomless Token for additional end-stroke support since the Pike’s updated DebonAir+ spring is considerably more linear than the pre-2025 version.

I’ve set the fork’s rebound dial on the faster side (12/20 clicks) and have positioned both compression adjusters in middle of their tuning range for the time being.

2025 trek top fuel 9.8 gx axs
The new Charger 3.1 damper is a big improvement in terms of sensitivity.

Trek Top Fuel weight

Confirmed weight for our Trek Top Fuel 9.8 GX AXS test bike is 13.14kg with the tyres set up tubeless and without pedals.

It’s not as light as the previous generation Top Fuel we tested a couple of years ago, but then the new bike does come with a bigger Pike up front, a longer travel dropper post, and a heavier SRAM Transmission.

The Bontrager Line Comp 30 wheels are also on the heavy side (2,094g confirmed). These come fitted with thick plastic TLR rim strips and tubeless valves, providing a simple and secure tubeless interface. Thankfully the fit wasn’t as stupidly tight as the tyre/rim interface on the Supercaliber we reviewed last year.

2025 trek top fuel 9.8 gx axs weight
Our Trek Top Fuel test bike weighs in at 13.14kg.

This would be my first experience with the new generation Bontrager Gunnison and Montrose tyres, both of which feature a 2.4in width and a supple 120 TPI construction. They utilise the sturdier XT casing that incorporates full bead-to-bead and apex protection to reduce the chance of pinch-flats. That means they’re not the lightest with the Gunnison coming in at 967g and the Montrose at 1,004g.

As usual I fitted a CushCore XC insert in the rear wheel, and set pressures at 20psi up front and 22psi out back.

On the trail

I’ve only had limited time aboard the new Trek Top Fuel, so these are very much early impressions. Don’t fret however, as we’ll be following up this first ride article with a proper in-depth review and video in the near future.

Mind you, it only took a few pedal strokes to appreciate the Top Fuel’s efficient and responsive demeanour. It might be heavier than a dedicated short travel XC race bike, but it offers up impressively pert pedalling performance even with the shock’s low-speed compression dial set to the softest position. The rear end feels very much set-and-forget, with no real need to reach for the shock’s two-position lever.

2025 trek top fuel 9.8 gx axs
The new Bontrager Gunnison and Montrose tyres feature a supple 120 TPI casing and a triple rubber compound.

Heading across rockier singletrack, the new bike is noticeably sprightlier and springier than its predecessor. It’s comfortable and nicely damped, aided by the supple tyres and alloy rims.

The suspension is also top-notch, delivering great sensitivity front and rear. The new Pike is quickly becoming one of my favourite trail forks, with a considerably plusher action compared to the previous version. Paired to the Deluxe RCT shock, the Top Fuel is a smooth operator despite its modest travel.

It seems to manage its travel well too, with plenty of progression out back. I’m yet to bottom out the shock despite there being no volume spacers inside and with the Mino Link positioned it the more linear setting.

2025 trek top fuel 9.8 gx axs
With its new DebonAir+ spring, the RockShox Pike needs a bit more air pressure than is recommended in the Trailhead app. We fitted a Bottomless Token too.

On rougher descents I’ve been impressed at how active the rear end stays under braking, resulting in less scrabbling of the rear tyre across loose surfaces. This is a key advantage of a proper four-bar suspension platform over a single pivot flex-stay bike, with the Top Fuel providing more grip both up and downhill. Indeed it’s the way that it manages to balance this traction with its snappy pedalling manners that stands out on the trail.

Any downsides so far?

I’m yet to encounter any glaring issues with the new Trek Top Fuel, which has so far provided great all-round performance across technical XC singletrack.

I will say that the alloy wheels don’t feel overly responsive, which is likely due to a combination of weight and stiffness. While the Top Fuel’s steering is direct, there is some occasional lag between your hands and the front tyre.

2025 trek top fuel 9.8 gx axs
The SRAM Level brakes are ok, though upgrading them with the heavier HS2 rotors would be a good idea to boost power and reduce lever dead stroke.

We’re still unconvinced by the latest SRAM Level brakes, which suffer from a long lever throw that means you have to run the reach adjuster further out so they don’t contact the grips when you’re yanking on them. Being on the lighter side, the overall braking power is fine for me with the stock pads and 180mm Centerline rotors. However, those after more bite should consider upgrading to thicker HS2 rotors that will improve power while also reducing some of the lever’s dead stroke.

One other potential downside is that the Top Fuel will only fit a single bottle. This differs to the Spark and Epic EVO, both of which will accommodate two. It’s no bother for me, but may be an issue for some riders who prefer heading out on long rides without a hydration pack.

2025 trek top fuel 9.8 gx axs
The most adaptable XC bike on the market? Quite possibly!

Flow’s Early Verdict

First impressions of the new 4th generation Trek Top Fuel are so far mostly positive. While it might look much the same as its predecessor, the lighter frame and refinements to the geometry and suspension design are noticeable on the trail. It feels enthusiastic and sporty to ride, offering up impressive pedal efficiency with loads of grip on tap.

The new 4-way Mino Link and up-stroke capability gives it a few nifty tricks up its sleeve, and I’m eager to explore some of the various setup options over the coming weeks. Given the snappy pedalling performance, I really like the idea of fitting a lighter wheelset and a 120mm travel RockShox SID to turn the Top Fuel into a more race-focussed XC bike. I’m also curious about extending the fork and shock travel and fitting a 27.5in rear wheel to morph it into a lightweight trail bike.

If there’s any particular setup you’d like to see, or any specific questions you want answered, as always let us know in the comments. I’ll endeavour to address those in our in-depth review and video, which we’ll have coming your way soon. Stay tuned!


2025 Trek top fuel 9.9 xx axs
The Trek Top Fuel 9.9 XX AXS comes with the very best components including the SRAM XX SL Transmission.

2025 Trek Top Fuel 9.9 XX AXS

  • Frame | OCLV Carbon, ABP Suspension Design, 120mm Travel
  • Fork | RockShox Pike Ultimate, Charger 3.1 RC2 Damper, 130mm Travel
  • Shock | RockShox Deluxe Ultimate, RCT Damper, 185x50mm
  • Wheels | Bontrager Line Pro 30, Carbon Rims, 30mm Inner Width
  • Tyres | Bontrager Gunnison RSL XT 2.4in Front & Montrose RSL XT 2.4in Rear
  • Drivetrain | SRAM XX SL Eagle AXS Transmission 1×12 w/30T Crankset & 10-52T Cassette
  • Brakes | SRAM Level Ultimate 4-Piston
  • Bar | Bontrager RSL Integrated, Carbon, 27.5mm Rise, 820mm Width
  • Stem | Bontrager RSL Integrated, Carbon, 45mm Length
  • Seatpost | RockShox Reverb AXS, 34.9mm Diameter, Travel: 100mm (S), 170mm (M-XL)
  • Claimed Weight | 12.85kg
  • RRP | $18,499 AUD
2025 Trek top fuel 9.9 x0 axs
Next down the line is the Top Fuel 9.9 X0 AXS model that features the same Ultimate-level suspension and Reverb AXS dropper post, albeit with a cheaper X0 Transmission.

2025 Trek Top Fuel 9.9 X0 AXS

  • Frame | OCLV Carbon, ABP Suspension Design, 120mm Travel
  • Fork | RockShox Pike Ultimate, Charger 3.1 RC2 Damper, 130mm Travel
  • Shock | RockShox Deluxe Ultimate, RCT Damper, 185x50mm
  • Wheels | Bontrager Line Pro 30, Carbon Rims, 30mm Inner Width
  • Tyres | Bontrager Gunnison RSL XT 2.4in Front & Montrose RSL XT 2.4in Rear
  • Drivetrain | SRAM X0 Eagle AXS Transmission 1×12 w/30T Crankset & 10-52T Cassette
  • Brakes | SRAM Level Silver 4-Piston
  • Bar | Bontrager RSL Integrated, Carbon, 27.5mm Rise, 820mm Width
  • Stem | Bontrager RSL Integrated, Carbon, 45mm Length
  • Seatpost | RockShox Reverb AXS, 34.9mm Diameter, Travel: 100mm (S), 170mm (M-XL)
  • Claimed Weight | 13.1kg
  • RRP | $15,499 AUD
2025 Trek top fuel 9.8 xt
The 9.8 XT model is quite a bit more expensive than the GX AXS model, despite coming with a cable-activated drivetrain.

2025 Trek Top Fuel 9.8 XT

  • Frame | OCLV Carbon, ABP Suspension Design, 120mm Travel
  • Fork | RockShox Pike Select+, Charger 3.1 RC2 Damper, 130mm Travel
  • Shock | RockShox Deluxe Ultimate, RCT Damper, 185x50mm
  • Wheels | Bontrager Line Comp 30, Alloy Rims, 30mm Inner Width
  • Tyres | Bontrager Gunnison RSL XT 2.4in Front & Montrose RSL XT 2.4in Rear
  • Drivetrain | Shimano XT 1×12 w/30T Crankset & 10-51T Cassette
  • Brakes | Shimano XT 4-Piston
  • Bar | Bontrager RSL Integrated, Carbon, 27.5mm Rise, 820mm Width
  • Stem | Bontrager RSL Integrated, Carbon, 45mm Length
  • Seatpost | Bontrager Line Dropper, 34.9mm Diameter, Travel: 100mm (S), 170mm (M-XL)
  • Claimed Weight | 13.45kg
  • RRP | $10,599 AUD
2025 Trek top fuel 9.8 gx axs
We reckon the Top Fuel 9.8 GX AXS model offers the most appealing back-for-buck out of the entire range.

2025 Trek Top Fuel 9.8 GX AXS

  • Frame | OCLV Carbon, ABP Suspension Design, 120mm Travel
  • Fork | RockShox Pike Select+, Charger 3.1 RC2 Damper, 130mm Travel
  • Shock | RockShox Deluxe Ultimate, RCT Damper, 185x50mm
  • Wheels | Bontrager Line Comp 30, Alloy Rims, 30mm Inner Width
  • Tyres | Bontrager Gunnison RSL XT 2.4in Front & Montrose RSL XT 2.4in Rear
  • Drivetrain | SRAM GX Eagle AXS Transmission 1×12 w/30T Crankset & 10-52T Cassette
  • Brakes | SRAM Level Bronze 4-Piston
  • Bar | Bontrager RSL Integrated, Carbon, 27.5mm Rise, 820mm Width
  • Stem | Bontrager RSL Integrated, Carbon, 45mm Length
  • Seatpost | Bontrager Line Dropper, 34.9mm Diameter, Travel: 100mm (S), 170mm (M-XL)
  • Claimed Weight | 13.2kg
  • RRP | $8,999 AUD
2025 trek top fuel 8
The cheapest model is the Top Fuel 8, which is the only bike to feature an alloy frame.

2025 Trek Top Fuel 8

  • Frame | Alpha Platinum Alloy, ABP Suspension Design, 120mm Travel
  • Fork | Fox 34 Rhythm, GRIP Damper, 130mm Travel
  • Shock | Fox Float DPS, 3-Position Damper, 185x50mm
  • Wheels | Bontrager Line Comp 30, Alloy Rims, 30mm Inner Width
  • Tyres | Bontrager Gunnison Pro XR 2.4in Front & Montrose Pro XR 2.4in Rear
  • Drivetrain | Shimano SLX/XT 1×12 w/30T Deore Crankset & 10-51T Cassette
  • Brakes | Shimano Deore 4-Piston
  • Bar | Bontrager Line, Alloy, 27.5mm Rise, 780mm Width
  • Stem | Bontrager Elite, 45mm Length
  • Seatpost | Bontrager Line Dropper, 34.9mm Diameter, Travel: 100mm (S), 170mm (M-XL)
  • Claimed Weight | 14.58kg
  • RRP | $5,499 AUD
2025 trek top fuel 9.8 gx axs
Early impressions are positive, though we’ll have an in-depth review and video of the new Trek Top Fuel coming soon!

ABOUT THE REVIEWER - Wil Barrett

Hometown

Bendigo, Victoria

Height

175cm

Weight65kg

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