Trek Top Fuel 9.9 XX1 AXS Review

Heading into the 2022 model year, Trek made significant changes to the Top Fuel lineup. The entire bike was re-imagined with more emphasis on capability, control, versatility and climbing. With those changes, the Top Fuel can be a downcountry roller or an efficient XC racer — you choose. Testing the range-topping Trek Top Fuel 9.9 XX1 AXS has been a gas since the first pedal stroke.

2022 Trek Top Fuel 9.9 AXS Features:

• 120mm rear travel mated with 120mm forks
• Active Braking Pivot suspension design
• Optimized anti-squat throughout the travel range
• 70-degree seat tube and 66-degree head angles
• Mino Link high setting steepens angles by 0.4-degrees, raises BB by 7mm
• Knock Block 2.0 offers 72-degrees of turning and keeps cables from getting pulled in a crash
• Bontrager RSL MTB integrated Handlebar/Stem
• Internal frame storage for tools, food, spare, etc.
• Fully-wireless SRAM XX1 AXS groupset
• RockShox Reverb AXS dropper
• RockShock SID Ultimate fork and Deluxe Ultimate RCT shock
• SRAM Level Ultimate brakes with carbon levers
• Bontrager Line Pro 30 wheelset
• Bontrager Team Issue XR4 2.4″ (XR3 2.4″ also tested)
• Bontrager Arvada saddle
• 29×2.5″ max tire clearance
• Weight: 26.7 lbs (M/L actual)
• MSRP: $11,499.99

Range-topping spec

Before the Top Fuel 9.9 XX1 AXS arrived, I didn’t know which trim level it was. I assumed a more midrange, journeyman spec, but when the 9.9 arrived, I was floored at the spec. XX1 AXS wireless shifting, top-range components and a beautiful Carbon Red Smoke/Trek Black Project One color fade. Calling this bike a “looker” doesn’t do it justice. No, it’s a no-holds-barred head-turner and it’s built to ride fast.

Two years ago, I rode and loved the Trek Supercaliber 9.8 and it still holds every climbing PR I ride. With the Top Fuel 9.9 coming in three pounds heavier and a more all-mountain vibe, the Trek marketing team said “you just might get some descending PR’s to go along with the climbing ones on the Supercaliber!” Well… I would definitely have to give it a good shot.

I’m a fan of SRAM AXS for road and gravel and did enjoy testing the GX Eagle AXS Upgrade Kit last year, but is electronic shifting all it’s cracked up to be for mountain bikes? There’s something to be said for the crisp, mechanical shifting you can get on SRAM XX1 Eagle, but pushing a button and getting instant shifts without all the wires is a slam dunk. Of course, the RockShox Reverb AXS dropper makes sense with wireless shifting, so I’m glad to have both. Icing on top is the complete suspension gamut of the RockShox SID Ultimate and Deluxe Ultimate RCT. But, let’s not forget the Bontrager Line Pro 30 carbon wheels and the RSL Integrated Bar/Stem while we’re at it. Those two items put the exclamation point on the entire package.

The Line Pro 30 wheels offer 29mm internal width for proper tire support and are honestly a little heavier than a set of pure XC Wheels at 1760 grams, but that’s a sacrifice I’ll take. After having ridden and damaged the lighter Fulcrum Red Zone 3’s, I appreciate the durability and confidence of Bontrager’s Carbon Care lifetime warranty. I ride low pressures (22/24 psi.) and have sustained some impacts, but the Line Pro 30’s don’t know the wiser.

As mentioned, the full bike comes in just under 27 lbs., which isn’t the lightest 120mm bike, but still a pound lighter than the Santa Cruz Tallboy CC 4 X01. For comparison, the Cannondale Scalpel SE LTD is just a touch lighter and the Specialized S-Works Epic EVO is over 4 lbs. lighter than the Top Fuel. It’s a competitive space out there, but I’d say the Top Fuel certainly isn’t bogged down by its weight.

Setup, fit and more

On paper, I felt like the large should be my jam and I was set on that. As availability of M/L’s became more of a reality, I swung down to the local Trek Bicycle American Fork store to check one out. I was fresh off a morning road ride, and still in my kit when my new friend Grant swooped in to the rescue. He walked me over to Trek’s in-store, electronic sizing system to determine my measurements and sizing. As it turns out, I’m actually a M/L in Trek mountain bikes. Problem solved. Technology for the win!

With successive generations of bike models, the trend is always to make the bike longer, lower and slacker. That recipe was applied to the 2022 Top Fuel. Frames now offer 10mm more reach, a 66-degree head angle (1.5 degrees slacker), 70-degree seat tube angle (2-degrees steeper) and ~40mm longer wheelbase throughout the lineup. Those changes are not minimal and comfortably take the Top Fuel into trail bike territory. As I discovered, with the Mino Link in low mode and grabby XR4 tires, there’s little that the Top Fuel can’t handle. Then, in high mode, with faster tires, the Top Fuel can double as an XC ripper while still rocking any downhill.

Initially, the Bontrager RSL Integrated handlebar/stem seemed short to me (it still kinda does), but the modest 27.5mm rise and ultra-wide 820mm width delivers a confident feel with added comfort. Effectively, it’s a 45mm stem length and I wished for just a little more reach, but that’s as much reach as you can get with this cockpit. The Bontrager Arvada 138mm saddle has been delightful throughout my testing with zero discomfort. I did swap out the grips for a set of Ergon GE1 Evo’s, but everything else remained stock — until I changed the tires out for a set of XR3’s near the end of my test miles.

As a friendly PSA, be sure to check your rebound settings before heading out for the first time. Typically, bikes arrive with rebound in the middle. I didn’t think much of it and after the RockShox SID Ultimate was found to be in the middle, I assumed the SID Luxe was set up the same. But… I was wrong. After a head-scratching ride with disappointing suspension performance, I checked the rebound and found it to be all the way in (slowest setting). Doh! That explained everything I was experiencing. I then put it one click in from the middle setting and have enjoyed the plush and responsive suspension feel I assumed I would get.

To dial in the suspension, I used Trek’s awesome suspension calculator, which suggested 93 psi. front and 170 psi. rear. I went with 85 psi. up front and 170 psi in the rear for my 173 lb. rider weight. To me, that feels great.

You can take the low mode, but I’ll take the high mode

As mentioned, the reversible Mino Links can change the characteristics of the Top Fuel. Yes, it’s noticeable and yes, it’s worth testing out on the terrain you typically ride. My rides consist of twisty and fast singletrack with interspersed rock gardens or other obstacles. At this stage, I’m not taking huge drops, nor am I charging full-steam into World Cup downhill courses. I ride fast on the downhill and love nothing more than flying down sinuous singletrack with bermed-out corners. But, the real truth is, I love to climb. Nothing is more rewarding to me than spanking an intense, long effort completely out of breath. And, as it turns out, the Top Fuel accommodates both desires quite well.

I’ll start with performance in the default, low setting. This is how the bike arrives and makes good use of the meaty Bontrager XR4 Team Issue tires. I spent about half of the 200 test miles in this setting and all the downcountry hype is real. Atop any descent, I felt confident rolling over and through just about anything. Not quite as plush as the Santa Cruz Tallboy, but it holds a line well and dances around or through obstacles as needed. You’ll still want to pick your lines, but rest assured that this playful descender can handle it.

Climbing in low mode, you’ll find that it’s certainly capable and able to ascend anything. Handling remains straight and it does well enough for most riders. But, as you’ll see below, high mode is preferred for extensive climbing.

It took me a whole 5 minutes to change to high mode. With slightly-steeper head and seat tube angles, it doesn’t feel twitchy at all. And, in fact, a 66.4-degree head angle is still among the most slack bikes in the 120mm travel bike category. It didn’t take long to realize that the high setting suits my riding style and terrain best. I’m climbing faster while actually descending faster at the same time. My guess is the faster handling is allowing me to take tighter lines on descents while being more efficient on the climbs.

Here are a couple of Strava segments showing just how well the Top Fuel performs for me in high settings. The first one is dominated by the Supercaliber, but the Top Fuel is the next fastest.

Everything feels balanced and capable on even the steepest climbs. I can pick my lines and the front end doesn’t wander even a little. I can sit on the nose of the Arvada and just power on up anything. When it comes to switchback climbs, the Top Fuel maintains momentum and swoops around corners at speed. Engagement with the Bontrager Line Pro 30’s is fast and responsive. I’ve got nothing but good things to say about the durability, comfort and speed of these wheels. Tubeless setup is a dream too.

To further capitalize on the high shock setting, I also swapped out the knobby XR4’s for a set of 2.4″ Bontrager XR3’s. If your idea of a good time is busting your lungs on endless climbs, I 100% recommend going in the high setting and getting faster treads. I’ve been analyzing my best times in each setting and while there is a clear winner on long climbs (high setting), it’s about even on the descents. With that, I have no reason to switch back — low mode is dead to me.

Playing with the terrain on descents, it’s apparent just how balanced and responsive the ABP Suspension is. There is a solid pedaling platform with a smooth progression throughout the travel. And, for my purposes, it feels bottomless on drops and then compresses and rebounds with an uncanny ability to propel me forward. Air time is natural and fun and manuals are easy to do. I really enjoy how much pop the balanced suspension provides — especially compared to the myriad of virtual pivot designs on the market.

On long rides, I did wish I could carry a larger bottle. The largest one I could fit was the Elite Fly 750ml bottle, which is great for rides up to 2 hours. Two bottles or at least room enough for an even larger one would be nice for a bike like the Top Fuel.

Performance of the SRAM XX1 AXS drivetrain has remained outstanding. I’m sold on electronic shifting on the road and gravel and do love it for mountain biking. But, as nice as it is, I’m just fine with mechanical shifting. But, the clean routing and the responsiveness of the RockShox Reverb AXS makes wireless a clear winner if you have the available funds. I really love the overall lack of handlebar clutter.

The RockShox SID Ultimate is an astounding fork. I haven’t noticed any lateral flex and the smooth travel makes quick work of rough terrain. No, it’s not as smooth as a PIKE, but it pairs perfectly with this bike. While I did fiddle with lockouts and stuff with the Supercaliber, I’ve just left everything open all the time on the Top Fuel. It has enough of a pedaling platform that I didn’t worry about any loss of power and it’s nice not to worry about switches or levers. Simplicity is always the best form of sophistication, right? Just air it up and ride.

The Good

• Full SRAM AXS wireless shifting looks clean and is instantaneous
• RockShox Reverb AXS is the pinnacle of responsive droppers
• Fuss-free suspension setup and performance
• RockShox SID is ultralight, stiff and responsive
• Downtube storage is a nice touch
• Mino Links allow for two different bike flavors
• Water bottle location is easily-reached and shielded from debris
• RSL Integrated handlebar/stem offers awesome handling and bike feel
• In low mode, it descends like a champ
• In high mode, it climbs really well (and still descends confidently)

The Bad

• Blendr mount needed to install a bike computer
• Wished the “stem” was 55mm long for a little more reach
• XR4 tires are a little slow for my tastes (I preferred the XR3’s)
• XX1 AXS shifter can sometimes feel less intuitive than mechanical
• Can only fit one, regular-sized water bottle

The Bottom Line: Trek Top Fuel 9.9 XX1 AXS

The 2022 Top Fuel is a capable all-rounder that handles rugged terrain while also being an ultra-efficient climber. It’s been interesting having the Top Fuel in the garage for so long now. Every time I swing a leg over it, I think I’ll just take it easy today and not push myself. But, all it takes is one pedal stroke and the game is afoot. I just can’t help myself from pushing the limits on every ride. Note that the 2023 models are arriving now and may feature minor spec changes.

Buy Now: Visit TrekBikes.com

In Summary

9.0 Fast Fuel

What more can I say, other than this bike is an absolute blast. There are more efficient XC race bikes and there are more capable all-mountain bikes, but the latest Top Fuel confidently fills that gap. Of course, I'd like something a little lighter, but there's no shaking a stick at how well this bike climbs and then how fun it is to snake in/out of every turn on a long descent. (Note: The XX1 AXS model tested here is an example of the ultimate build, but you don't have to spend nearly that much to get almost the same performance.)

• Handling 9
• Climbing 10
• Descending 9
• Pedaling Efficiency 9
• Fun Factor 10
• Value 7