Trek’s Top Fuel 9.9 XX1 AXS is a rare bird. At first glance, you’d expect it to be a cross-country specialist. It’s wearing a RockShox Sid fork, after all. But after riding this bike on local trails here in Colorado as well as chunky trails in Moab that should have eaten the Top Fuel alive, Trek’s top of the line speed demon proved itself worthy on climbs — and surprisingly, on every descent.
Star Rating: ★★★★★
Price: $11,499
What I like: Geometry; carbon bar/stem combo; rear suspension action; calm handling
What I’d change: The price tag eliminates it as a possibility for most riders; should include flat tire tools
My call: An insane bike with an insane price tag. The Top Fuel 9.9 absolutely crushes ups and downs with way more capability than what we thought possible.
Trek Top Fuel 9.9 XX1 AXS: Build
Photo: Dan Cavallari | DawnPatrolMTB.com
Trek went all out on this Top Fuel 9.9 XX1 AXS build. It’s insanely expensive at $11,499. However, you’ll be hard-pressed to find a single part that needs updating.
It’s all carbon, all the time with a full Trek OCLV carbon frame and 29-inch Bontrager Line Pro 30 carbon wheels. RockShox’s top-end Sid Ultimate 120mm fork and Deluxe Ultimate RCT shock, Sram’s flawless XX1 AXS wireless shifting and G2 Ultimate disc brakes, and a wireless Reverb AXS dropper post round out the specs (note: my test bike had a Bontrager dropper post).
One of the standout features on this Top Fuel is the futuristic-looking, one-piece, full-carbon RSL handlebar/stem combo. Is it necessary? No, not really. Is it beautifully made, stunning to look at, and impressive to ride? Heck yes.
Kudos to Trek for its smart dimensions. The stem is 45mm (35mm on size Small) and the bars are a nutso 820mm wide. That’s really wide. Of course, most riders will chop a bit of that width off. The bar’s 27.5mm riser height and 7/6 degree back and up sweep worked well for my wrists and positioning. But it was the ride that impressed me the most. Bontrager nailed the stiffness to damping ratio, and the subtle graphics are spot on, too.
Another love/hate Trek feature is Trek’s Knock Block 2.0 headset system. It’s an integrated stop to prevent the fork’s dials, or some severely angled brake levers from smacking into the frame should things go pear-shaped. Trek updated this feature so it now allows the bars 72 degrees of rotation, up from 58 degrees before. It never impeded any cornering. And it’s removable.
Trek Top Fuel XX1 AXS: The ride
Photo: Dan Cavallari | DawnPatrolMTB.com
Trek truly nailed mountain biking with the Top Fuel. It’s supremely fun and capable on trails, up and down.
On the climbs, the Top Fuel is light and responsive. Trek’s Active Braking Pivot rear suspension and RockShox rear shock tune keep the Top Fuel feeling lively, especially when ascending the rough stuff. The front end is low (605mm, Large) when taken into consideration to the rest of the geometry. It allowed me to scamper up nearly unrideable climbs, not once, but twice, which surprised me and my riding buddies.
Now, there are some stiffer pedaling platforms out there, but what the Top Fuel lacks in responsiveness, it doubles up on traction.
On the downs, the control and confidence of the Top Fuel continually impressed me. This bike is smooth and fast. As a complete rig, there’s a lot of carbon (front and rear frame, wheels, bars, stem). Big, cushy 2.4-inch XR4 tires, and RockShox’s best suspension bits also combine to nullify a lot of the buzz and trail feedback that can plague metal bikes, or those rolling on lesser forks and shocks. There’s a noticeable calm to the Top Fuel.
It’s easy to ride at speed and doesn’t take loads of skill to unleash its potential. Imagine a smooth, quiet, fast sports car. You look at the speedometer and can’t believe you’re doing 90mph. This bike is like that. I’d dare say it can make you a better rider.
On one of my favorite test tracks, there’s a mess of roots followed by a very square-edged drop that immediately slams into a tight left corner. Typically, bikes under 140mm squirm and moan, clacking the bottom of their travel and twisting out of shape. The 120mm Top Fuel blasted through with more precision (and less complaint) than any short-travel bike in recent memory.
Descents and componentry
The long wheelbase (1,215mm, Large) and beautifully slack 66-degree head angle add a certainty on the jagged, steep stuff that was borderline unthinkable from a 5-inch-travel bike just two to three years ago.
That’s not to say the Top Fuel is some gravity monster. It’s nowhere close to today’s dialed enduro bikes, but it does take some considerably janky and long tracks for its suspension to begin to feel overworked.
If I’m pressed to be nit-picky, Trek’s rear suspension and RockShox Ultimate Deluxe RCT shock have better tune than the Sid Ultimate fork. When pushed hard on long, sustained downhills, the Sid fork found its limits before the rear end. That said, this latest Sid fork is light years ahead of its previous iterations.
Oddly, I’m not in love with the SRAM AXS wireless shifting. The shifter buttons are a bit foreign, which I find odd given that SRAM could have (should have) directly copied their analog shifter paddles. Also, in the low range of the cassette, the shifting was off, grinding and popping ever so slightly. And the AXS gear changes seemed slower than an X0 derailleur pulled by a cable.
The neat, rattle-free tool roll in the snack hole under the water bottle mount is empty. It shouldn’t be. For $11,499, Trek could throw in a Bontrager Co2 head, cartridge, and tube. And maybe a mini-tool.
Trek Top Fuel 9.9 XX1 AXS: Final word
Photo: Dan Cavallari | DawnPatrolMTB.com
Who should buy this top-tier rig? It’s ideal for the well-heeled rider looking for the ultimate singletrack weapon. There are few trails where the Top Fuel is out of place or in over its head. It has the rare ability to crush the climbs and still be super fun on the descents.
Trek Top Fuel 9.9 XX1 AXS Review
High end and incredibly fun
Trek's top-end bike is loaded with tech and capability. It's an impeccable XC and trail bike ready for nearly any terrain, as long as you have the coin.
