13.5 kg in size L | € 6,999 | Manufacturer’s website
Trek is one of the biggest bike manufacturers in the world, and is entering our trail bike comparison test with the Top Fuel, a versatile MTB bike that has already secured victory in our latest downcountry bike group test. Since then, it has been further refined and now features 130/120 mm of front travel, which makes it the shortest-travel competitor in this test. However, at just 13.5 kg, it’s also the lightest one.
The Trek Top Fuel 9.8 spec variant we tested retails at €6,999, which makes it the second most affordable bike in this test. On paper, it looks like an exciting option for riders seeking an efficient trail bike with good value for money. But how does it hold up against competitors with significantly more travel?
For an overview of the test field head to our “Best trail bike of 2025” comparison test – 16 of the most exciting trail bikes in our 2025 group test
The Trek Top Fuel 9.8 GX AXS in detail
The Trek Top Fuel 9.8 GX AXS stays true to Trek’s classic design language, featuring an organic frame silhouette and a vertically mounted shock. The ABP (Active Braking Pivot) rear suspension, with a pivot point on the rear axle, is designed to keep the suspension active even under braking. Compared to the rest of the test field, the frame is skinnier and, with the matte finish and somewhat old-school frame design, doesn’t look as refined as some of its competitors. However, the red anodized components add a striking accent to the overall look – though design is always a matter of personal taste.
The cables are routed internally and disappear into the frame behind the headset and are pleasantly quiet on the trail despite not being clamped at the ports. The chainstay protector prevents chain slap, adding to the silent riding experience.
The storage compartment features a secure closure and practical storage pouches, though the small opening makes it awkward to access. Additionally, a tool mount under the top tube provides space for essential trail tools.
The spec of the Trek Top Fuel 9.8 GX AXS
The Trek Top Fuel 9.8 GX AXS comes with a well-thought-out spec, though you get the feeling that Trek tried to cut corners with some components. The 130 mm RockShox Pike Select+ fork shares the same damper as the top-tier Ultimate model but lacks the ButterCups vibration dampers. At the rear, a RockShox Deluxe Ultimate air shock manages 120 mm of travel, but since it lacks a piggyback reservoir, it can overheat quickly on long descents, causing the suspension to stiffen up.
The Bontrager Line dropper post offers 170 mm of travel, falling short of the 197 mm test average, thus limiting freedom of movement on technical trails. The SRAM Level Bronze brakes with 180 mm rotors front and rear are on the weak side too, robbing you of confidence on longer descents.
Shifting is taken care of by a SRAM GX Eagle Transmission drivetrain, which relies on a direct-mount rear derailleur and delivers precise, reliable shifting even under load. The Bontrager RSL Onepiece cockpit, which integrates the stem and handlebars into a single unit with a 35 mm stem length, looks sleek but has its downsides. We trimmed the 820 mm stock bars to 790 mm, which we recommend to avoid feeling like you’re steering a bus. It’s a shame that even size S comes with an oversized 820 mm handlebar bar, forcing you to cut it down significantly, and making an already stiff cockpit even stiffer as a result. On top of that, the one-piece design doesn’t allow for ergonomic fine-adjustments.
For the wheels, Trek rely on their in-house Bontrager components, combining a 29” Line Comp 30 wheelset and Gunnison RSL XT lightweight tires, which offer minimal rolling resistance but offer minimal puncture protection – and traction in loose and wet terrain isn’t great either. . . For better trail performance, we recommend upgrading to tires with a more robust casing and more aggressive tread pattern like the Bontrager Line Pro 30.
Trek Top Fuel 9.8 GX AXS
€ 6,999
Specifications
Fork RockShox Pike Select+ 130 mm
Rear Shock RockShox Deluxe Ultimate 120 mm
Seatpost Bontrager Line Dropper 170 mm
Brakes SRAM Level Bronze 180/180 mm
Drivetrain SRAM GX Eagle Transmission 1x12
Stem Bontrager RSL onepiece 35 mm
Handlebar Bontrager RSL onepiece 790 mm
Wheelset Bontrager Line Comp 30 29"
Tires Bontrager Gunnison RSL XT/Bontrager Gunnison RSL XT 2,4"/2,4"
Technical Data
Size S M ML L XL
Weight 13,5 kg
Specific Features
Storage
Toolmount
Flip Chip
Tuning Tip:
– More powerful brakes
– Conventional two-piece cockpit
– Tires with a more durable casing and aggressive tread pattern
The geometry of the Trek Top Fuel 9.8 GX AXS
The Trek Top Fuel 9.8 GX AXS is available in five sizes, S to XL, with an additional ML size between M and L providing more options in the most popular size range. Size S comes standard with 27.5-inch wheels, while M through XL feature 29” wheels front and rear.
The geometry is the most conservative in the test field, making the Trek feel more like an XC bike than a trail bike. The 65.5° head angle is the steepest in this test, while the 75.9° seat angle is relatively slack. Our test bike in size L combines 478 mm reach and a relatively long 435 mm seat tube, which, combined with the short dropper post, further limits freedom of movement.
The Trek Top Fuel combines organic frame shapes with striking red accents – an outdated look that fails to stand out in the test field!
The four-position Mino Link, which is placed on the lower shock mount, allows you to adjust the rear suspension progression between 14% and 19%, as well as the bottom bracket height, seat angle, and head angle. In the high setting, the angles are all 0.5° steeper, while the bottom bracket is 6 mm higher. We rode the bike mainly in the lower, less progressive setting, which offers more reserves and stability.
| Size | S | M | ML | L | XL |
|---|---|---|---|---|---|
| Seat Tube | 360 mm | 410 mm | 420 mm | 435 mm | 470 mm |
| Top Tube | 558 mm | 587 mm | 611 mm | 629 mm | 648 mm |
| Head Tube | 105 mm | 110 mm | 115 mm | 120 mm | 125 mm |
| Head Angle | 65.9° | 65.9° | 65.9° | 65.9° | 65.9° |
| Seat Angle | 69.5° | 70.0° | 70.5° | 70.5° | 70.5° |
| Chainstay | 434 mm | 435 mm | 436 mm | 439 mm | 439 mm |
| Bottom Bracket Drop | 40 mm | 40 mm | 40 mm | 40 mm | 40 mm |
| Wheelbase | 1151 mm | 1180 mm | 1210 mm | 1227 mm | 1243 mm |
| Reach | 427 mm | 442 mm | 460 mm | 477 mm | 492 mm |
| Stack | 566 mm | 579 mm | 607 mm | 612 mm | 626 mm |
The Trek Top Fuel 9.8 GX AXS on the trail
As soon as you swing your leg over the saddle of the Trek Top Fuel 9.8 GX AXS, you’ll notice the slack seat angle, which places you far behind above the rear wheel. However, the position isn’t overly stretched forward, and is still comfortable enough for long days in the saddle. On level ground and moderate climbs, the Top Fuel plays to its strengths and ranks among the best analogue climbers in this test. However, on steeper uphills, you’ll have to actively weight the front wheel to keep it tracking.
The handling is rather demanding and requires plenty of physical effort, especially on steeper and rougher trails, where the bike struggles to hold its line. Overall, the Top Fuel is unforgiving of riding mistakes, requiring a precise, vigilant riding style in nasty rock gardens and root carpets. On technical trails, it can feel like a rodeo bull, constantly demanding active input to stay in control. As a result, the Top Fuel is the least composed bike in this test.
On technical trails, you’ll have to slow down and carefully pick your line, as the limited travel quickly reaches its limits. While your riding buddies on trail bikes will likely leave you behind, the Top Fuel comes alive on smooth and flowing trails. Here you can quickly close the gap to your friends by pumping through the trail, provided you ride aggressively enough – though the bike sometimes feels faster than it is.
XC bike out of its element – the Trek Top Fuel offers little confidence on the trail and falls behind the competition.
The suspension is well-balanced but firmly tuned, and with less travel than most competitors, it feels noticeably harsher. Grip is limited on challenging terrain, which is partly due to the lightweight, shallow-profiled tires, which struggle to gain traction on wet or loose trails. However, the highly efficient suspension and excellent mid-stroke support make it incredibly fun on flow trails, where the Trek quickly picks up speed.
Who should take a closer look at the Trek Top Fuel 9.8 GX AXS?
The Trek Top Fuel 9.8 GX AXS is an excellent choice if you’re riders looking for a XC-inspired bike that can also handle light trail riding. The sporty riding position ensures excellent power transfer to the pedals, which makes it highly efficient and responsive on climbs.
If you’re looking for more downhill performance, we recommend upgrading to more robust tires and stronger brakes to unlock the bike’s potential, and make it suitable for more demanding trails.
Conclusions about the Trek Top Fuel 9.8 GX AXS
The Trek Top Fuel 9.8 GX AXS aims to be a trail bike but rides more like an XC bike out of its element. Thanks to the sporty riding position, it’s efficient and lively on climbs, but struggles with limited reserves and stability on descents, which makes it demanding on technical trails. Its true strength lies on flow trails, where it excels with precise handling and excellent speed. However, on natural, uneven terrain, it falls noticeably behind the competition, requiring an active riding style and good skills to stay in control.
Tops
- Very efficient climber
- Extensive adjustability options
Flops
- Very little stability at speed
- Demanding handling
- Underwhelming component choices
- Less premium-looking design
For more info head to trekbikes.com.
The test field
For an overview of the test field head to our “Best trail bike of 2025” comparison test – 16 of the most exciting trail bikes in our 2025 group test
All bikes in test: Atherton S.150 | Canyon Spectral CF LTD | Canyon Spectral:ONfly CF LTD | Ibis Ripmo XT | MERIDA eONE-SIXTY SL | Norco Optic C1 | Orbea Rise LT M-LTD | Pivot Switchblade Team X0 Transmission | RAAW Jibb V2 | Rocky Mountain Instinct C70 | Santa Cruz Bronson CC X0 AXS RSV | Santa Cruz Hightower CC X0 AXS RSV | Specialized S-Works Stumpjumper 15 | Transition Sentinel X0 AXS | Trek Top Fuel 9.8 GX AXS | YT JEFFSY CORE 5 CF
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Words: Simon Kohler Photos: Peter Walker
