Takeaway: Trek’s latest edition of the Top Fuel moves from being a big cross country racer and becomes a short travel trail bike. With new longer and slacker geometry, plus 5mm of extra travel, it aims to give riders the efficiency they want for long days while still enabling them to ride more technical trails with confidence.

  • Fully guided internal routing in the front triangle plus a 73mm BSA threaded bottom bracket simplifies maintenance for both professional and home mechanics.
  • The new Top Fuel has clearance for 2.5” tires; which makes perfect sense as even XC racers are now running 2.4” tires as standard.
  • The downtube storage compartment is now featured on all Top Fuel models, including the alloy versions. It’s a great feature that often gets nixed on lower priced frame models.
    trek top fuel
    Trevor Raab

    Trek Top Fuel 9.9 XX1 AXS Build Details

    Price: $11,500
    26.8lbs (size XL)
    Full suspension 120mm trail bike
    OCLV Mountain Carbon, internal storage, tapered head tube, Knock Block 2.0, internal guided routing, downtube guard, magnesium rocker link, Mino Link, ABP, Boost148, 120mm travel
    Wheel Size:
    RockShox SID Ultimate, DebonAir spring, Charger Race Day damper, tapered steerer, 44mm offset, Boost110, 15mm Maxle Stealth, 120mm travel
    Rear Shock:
    RockShox Deluxe Ultimate RCT, 185mm x 50mm
    SRAM Eagle AXS, wireless, 12-speed
    SRAM XX1 Eagle, DUB, 55mm chainline, 175mm length
    30 tooth
    SRAM Eagle XG-1299, 10-52T, 12-speed
    SRAM G2 Ultimate hydraulic disc, carbon levers
    Front Wheel:
    Bontrager Line Pro 30, OCLV Mountain Carbon, Tubeless Ready, 6-bolt, Boost110, 15mm thru axle
    Rear Wheel:
    Bontrager Line Pro 30, OCLV Mountain Carbon, Tubeless Ready, Rapid Drive 108, 6-bolt, SRAM XD driver, Boost148, 12mm thru-axle
    Tires: Bontrager XR4 Team Issue, Tubeless Ready, Inner Strength sidewalls, aramid bead, 120tpi, 29.x2.40''
    Bontrager Arvada, austenite rails, 138mm width
    RockShox Reverb AXS, 170mm travel, wireless, 34.9mm, 480mm length
    Handlebar / Stem:
    Bontrager RSL Integrated handlebar/stem, OCLV Carbon, 27.5mm handlebar rise, 820mm width, 0 degree stem rise, 45mm stem length

    trek top fuel
    Trevor Raab

    Since 2019, Trek’s Top Fuel has been sandwiched between the brand's laser focused Supercaliber cross country race bike and its trail oriented Fuel EX platforms. The previous generation Top Fuel was ahead of its time in many ways; with 120mm front and 115mm rear travel, a remote lockout on certain models, and low overall weight. Trek pitched the previous Top Fuel as a marathon distance race bike. But that was before 120mm travel platforms began popping up in World Cup XC races.

    trek top fuel
    Trevor Raab

    While XC race bikes were becoming longer travel, yet another new category of mountain bikes started to gain traction with riders: down-country. This new breed of bikes combines elements of longer travel all-mountain and trail bikes (such as slack geometry, more powerful brakes, and heavier casing tires) with shorter travel and lighter-weight frames. Essentially, burly XC bikes that you can ride all day, are efficient climbers, and very capable at descending. This is the approach Trek took with the latest Top Fuel.

    trek top fuel
    Trevor Raab

    The new Top Fuel strikes a similar silhouette to the older model, with a vertically mounted shock layout and Trek’s Active Braking Pivot suspension system; which now delivers an extra 5mm of travel in the rear to match the 120mm travel fork. The Top Fuel’s geometry is in line with other bikes in the emerging down-country category, with the headtube angle becoming 1.5 degrees slacker and reach increasing by 10mm as compared to the previous generation of the bike. The Top Fuel now also has clearance for 2.5 inch tires, for those who want to push traction to the limit.

    trek top fuel
    Trevor Raab

    The new Top Fuel edges ever closer into the territory of its longer travel sibling, the Fuel EX. The updated geometry of the Top Fuel actually makes the Fuel EX look a bit dated in comparison. The two bikes have identical headtube angles, with the Top Fuel having a longer reach and a steeper seat angle as well. You can even fit a 130mm fork on the Top Fuel, which would make it slacker than the Fuel Ex. Basically, the Top Fuel is no longer a race oriented bike. It has now morphed into an efficient trail bike for riders that still want solid pedaling performance to get up the climbs, but who want additional speed, confidence, and control on the descents.

    Builds & Pricing

    There are a total of nine different Top Fuel builds offered by Trek, plus carbon and alloy framesets. The Top Fuel is also available through Trek’s Project One program, allowing riders to customize everything from components to paint.

    We got to test the Top Fuel 9.9 XX1 AXS build, which at $11,050 is (depending on your perspective) either a reasonable price for a modern high end bicycle or completely bonkers. With bikes such as Specialized S-Works Epic EVO coming in at a cool $13,000, and the Scott Spark 900 Ultimate EVO AXS at $14,000, the Top Fuel 9.9 almost seems price conscious.

    The cheapest Top Fuel model, the alloy framed Top Fuel 5, features a RockShox Recon fork, X-Fusion X-Pro2 shock, and a Shimano Deore drivetrain at $2,630. The Top Fuel 7 has a Recon Gold fork with a mix of Shimano SLX and XT parts, plus Bontrager Line Comp wheels for $3,530. The Top Fuel 8 is the priciest alloy build at $3,830, with a RockShox SID fork and Deluxe Ultimate shock plus more powerful Shimano M6120 four-piston brakes.

    The Top Fuel 9.7 is the most affordable of the carbon builds at $4,230. It uses Fox Rhythm 34 fork with a Float DPS shock and is finished with a mix of Shimano SLX and XT, plus Bontrager Line wheels. The Top Fuel 9.8 has three different versions based on your component preferences. You can go mechanical with SRAM GX or Shimano XT for $7,050 or upgrade to GX AXS for $7,550. All three use RockShox SID Select+ forks and Deluxe Ultimate RCT shocks, along with Bontrager Line Elite 30 wheels. Moving to the top of the price range, for $9,550Trek offers the Top Fuel 9.9 XTR build for Shimano and Fox lovers. It uses Fox Factory level suspension, a full mechanical XTR drivetrain, and Bontrager Line Pro 30 wheels. Riders preferring Rockshox Ultimate level suspension and electronic XX1 AXS shifting will need to spend $11,050 to get the most expensive Top Fuel model, the 9.9 XX1 AXS.

    If you’d rather build your bike from the frame up, Trek offers alloy and carbon framesets. The Top Fuel AL frame sells for $2,320 with a Fox Float DPS shock. The carbon frame is priced at $3,720 and includes a Fox Factory Float DPS shock.

    Geometry & Fit

    The new Top Fuel has received the slacker and longer treatment, and as a result, the head tube angle is now a degree and a half slacker at 66º across the entire size range. Reach grows by 10mm while BB height and chainstay length remain the same from the previous generation.

    Trek offers seven different sizes of the Top Fuel, including an M/L option for riders often caught between the medium and the large. With a stock stem length of 45mm on all sizes except an XS, our 6’3 tester felt cramped on the size XL and likely would have benefited from sizing up to an XXL. The issue was resolved with a longer stem, but the most expensive 9.9 builds of the Top Fuel Trek use its integrated Bontrager RSL handlebar and stem combo. It’s easy enough to swap out as it thankfully doesn’t run any lines internally, but it still means riders will need to supply both a bar and a stem to make fit adjustments. As always, it’s highly recommended that you get a test ride in at a shop before buying a new bike if possible.

    trek top fuel
    Trevor Raab

    Ride Impressions

    The new Top Fuel is very much a short travel trail bike meant for ripping down burly trails. Thanks to a 40mm increase in wheelbase, a slacker head tube angle, and other geometry changes over its previous version, it feels much more planted and composed on rough and fast descents. It’s a bike that wants to hold a line and stay planted on the ground. This worked well in certain situations, like scrubbing speed on a rough bit of trail heading into a turn. Other times it made me have to fight the bike a bit to make quick line adjustments.

    trek top fuel
    Trevor Raab

    To highlight the new trail bike character of the Top Fuel, Trek has made some component choices to suit the bike's new intended purpose. Opting for four-piston SRAM G2 brakes, as well as grippier XR4 tires, for better control on steep descents. The frame is also beefed up with a larger downtube that now includes a storage compartment for snacks or, more likely, flat-fix tools. The seat tube also grows in diameter to increase stiffness and accommodate a larger diameter 34.9mm dropper post. The remote lockout is also gone from the handlebars – which, perhaps more than any other change, makes the Top Fuel's intent as a trail bike crystal clear.

    trek top fuel
    Trevor Raab

    Trek’s ABP suspension design has had many years of refinement and is a genuine four-bar platform, unlike many 120mm bikes that use a flex pivot. In contrast, all the pivot points on the Top Fuel use sealed bearings, resulting in a suspension setup that feels much more active. The design does a good job of isolating braking from the suspension, resulting in less skipping and bouncing when you’re hard on the brakes in a rough section of trail.

    trek top fuel
    Trevor Raab

    The downside of the Top Fuel’s trail bike transformation is that it’s now a bit heavy. Our premium 9.9 XX1 AXS XL sample came in at nearly 27 lbs. This isn’t wildly heavy for a trail bike, but typically you get a bit more suspension travel with that weight penalty. For reference, the Scott Spark I tested earlier this year has the same amount of suspension travel as the Top Fuel but is a full three pounds lighter. Trek does say that the Top Fuel is compatible with a 130mm fork, and I can’t help but think the new Top Fuel would have made a lot more sense with the increased travel straight from the factory.

    trek top fuel
    Trevor Raab

    After having multiple testers on the Top Fuel over the last few weeks, our consensus has been that the Top Fuel would thrive in a place that has a lot of machine built or well maintained, and steep trails. Trails where you can get the Top Fuel moving fast allow the progressive all-mountain geometry to shine and make the bike feel much more capable than its 120mm of travel would suggest.

    trek top fuel
    Trevor Raab

    The new Top Fuel is undoubtedly more capable than its previous version while maintaining much of its pedaling efficiency. Riders with more than a casual interest in racing should probably look at bikes such as the Scott Spark, Canyon Lux Trail, or Specialized Epic EVO. The Top Fuel is perhaps the ideal bike for riders who want a trail, or even all-mountain, bike geometry experience, but don't want the extra weight or need the extra bit of travel.

    Trek Top Fuel 9.9 XX1 AXS

    • Threaded bottom bracket and fully guided internal routing
    • Downtube storage on all models
    • Clearance for 2.5" tires

    • Heavy for 120mm travel bike