trek top fuel mountain bike

2022 Trek Top Fuel Review | All-new frame & geometry, with a whole new attitude

The not-so-minor details, 2022 trek top fuel 9.8 xt.

https://www.trekbikes.com/

- Brilliant trail-ripping geometry - Active and supportive suspension - Masses of cornering grip & stability - Refined and practical frame design - Downtube storage is a welcome addition

- Dropper post is sluggish - Wheels are solid but quite heavy - Carbon bars are harsh - Heavier than many of its competitors

Flow reviews the 2022 Trek Top Fuel

The Trek Top Fuel has long been known as the American brand’s flagship full suspension XC race bike, purpose-built to to compete at the very highest level of the sport. In more recent years however, the Top Fuel has steered in a different direction. With the short-travel Supercaliber taking over duties for World Cup XCO racing, Trek has softened the Top Fuel’s serious, race-focused persona, adding travel and bulking it up in the process.

For 2022, the Trek Top Fuel makes its biggest move away from its XC racing roots. Equipped with a brand new frame, an updated suspension design and some thoroughly modern geometry, the Top Fuel aims to retain the pert pedalling performance of its predecessor while significantly boosting its all-round capability. So, has Trek succeeded?

Watch our video review of the new Trek Top Fuel here:

Along with the active ABP suspension design and chunky tyres, there’s an exceptional amount of grip and support on offer for a 120mm travel bike.

Trek Top Fuel overview

Despite being all-new, the Trek Top Fuel retains its position in between the Supercaliber (the 60mm travel XC race bike) and the Fuel EX (the 130mm travel trail bike).

It’s equipped with a 120mm travel fork just like its predecessor, but rear travel has actually lifted by 5mm up to 120mm. This increase has been achieved with a longer stroke shock (50mm vs 45mm), and Trek has also flipped the orientation of the trunnion-mount. The rocker link now drives the shock via two sealed cartridge bearings to improve sensitivity.

You’ll no longer find a dual remote lockout on the Top Fuel, which leads to a vastly cleaner bike with fewer cables occupying your view from the cockpit. Along with the bigger shock, slacker geometry and 2.4in wide tyres, it is without doubt the most trail-oriented Top Fuel we’ve seen yet.

To put it into context, that sees it move away from the likes of the Orbea Oiz TR and the Canyon Lux Trail , and more towards the direction of the Santa Cruz Tallboy and Pivot Trail 429 .

A new, burlier chassis

Though it looks pretty similar, the Trek Top Fuel frame is all-new for 2022. It’s not so much a radical overhaul, but rather a collection of many small refinements that add up to a more practical package.

The chassis is notably beefier than its predecessor, with the seat tube diameter swelling to the new-school 34.9mm size. As well as increasing frame stiffness, the fatter seat tube is also shorter, allowing it to swallow a modern long-stroke dropper post.

The downtube is also larger, and it now features the integrated storage design we’ve seen employed on the latest Fuel EX and Slash. A latch underneath the bottle cage removes the trap door, providing you access within. A neat tool roll is included with the bike so you can carry a spare tube, levers and CO2. You could also fit a lightweight jacket in there along with some snacks.

Trek has updated the Knock Block headset, increasing the available turning radius from 58° to 72°. This provides you with greater freedom of movement on the trail, but still prevents the handlebar controls from smashing into the top tube. If you’re not into it though, the Knock Block is removable.

Also nice to see is a threaded bottom bracket shell for ease of maintenance, and the rear ABP pivot can now be tightened with a cassette tool. Also new for the Top Fuel is guided internal cable routing – poke the cable in at one end, and it’ll pop out the other, no fishing required.

Trail-leaning geometry

The 2022 Trek Top Fuel has received a series of geometry updates over the outgoing model, bringing it up to speed with other boundary-pushers in this travel bracket. Here are the key numbers;

• Head tube angle: 66°
• Seat tube angle: 76°
• Reach: 420mm (S), 450mm (M), 465mm (M/L), 480mm (L), 500mm (XL)
• Rear centre length: 435mm
• BB drop: 36mm

Compared to the old Top Fuel, the head angle has kicked back by 1.5-degrees and the reach measurements have gone up by 10mm. The seat tube angle has also steepened by 1-degree to improve the climbing position, while the chainstay length and BB drop remain the same.

The Top Fuel still features a Mino Link, but it’s now located at the lower shock eyelet. Bikes will come setup from the factory in the Low position. Flipping that into High will lift the BB height by 7mm and steepen the angles by 0.4°.

You can get even rowdier by fitting a 130mm travel fork, which will kick the head angle back to a very-slack 65.6° in the Low position. And for those wanting to push the needle further, there’s clearance to run 2.5in tyres.

Trek Top Fuel price & specs

We’ll see four Trek Top Fuel models coming into Australia this year – two with alloy frames and two with carbon. All Top Fuel models feature the same geometry, suspension design and travel. They’re all equipped with 29in wheels, and there are five frame sizes available from Small through to X-Large (the XS size with 27.5in wheels won’t be available in Australia).

Pricing kicks off at $3,499 AUD for the Top Fuel 5 and goes up to $8,299 AUD for the Top Fuel 9.8 XT that we have on test here. Additionally, Trek will offer a 9.9 spec via the Project One bike builder program.

You can check out the specs and prices for all those models down at the bottom of the page. Right now we’ll be diving straight into our experience of testing this bike here; the Top Fuel 9.8 XT.

• Frame | OCLV Mountain Carbon Fibre, ABP Suspension Design, 120mm Travel
• Fork | RockShox SID Select+, Charger 2 RL Damper, 44mm Offset, 120mm Travel
• Shock | RockShox Deluxe Ultimate RCT, 185x50mm
• Wheels | Bontrager Line Elite 30, OCLV Carbon Rims, 29mm Inner Width
• Tyres | Bontrager XR4 Team Issue 2.4in Front & Rear
• Drivetrain | Shimano XT 1×12 w/XT 30T Crankset & 10-51T Cassette
• Brakes | Shimano XT 4-Piston w/Ice Tech Rotors
• Bar | Bontrager Line Pro, OCLV Carbon, 27.5mm Rise, Width: 750mm (S), 780mm (M-XL)
• Stem | Bontrager Line Pro, 45mm Length
• Seatpost | Bontrager Line Elite Dropper, 34.9mm Diameter, Travel: 100mm (S), 150mm (M-M/L), 170mm (L), 200mm (XL)
• Saddle | Bontrager Arvada, Austentite Rails
• Confirmed Weight | 12.88kg (Large, Tubeless)
• RRP | $8,299 AUD

This differs from some other brands that utilise a single frame, and simply up-fork and up-shock it to create a slightly longer travel bike (like the Specialized Epic EVO and Orbea Oiz TR). The Top Fuel is not one of those bikes.

Trek Top Fuel sizing & fit

We put the new Trek Top Fuel into the hands of our tester Ben, who owns the current Top Fuel and has also spent considerable time on the Fuel EX. At 181cm tall, Ben’s been riding a size Large across all three bikes.

The Top Fuel is well-proportioned out of the box. The 480mm reach is very long, but it’s balanced nicely with a 50mm stem and the 76° seat tube angle. The Bontrager saddle is totally inoffensive, and we haven’t needed to shunt it into an extreme position just to get it comfortable.

The 760mm wide riser bars are a great match for this bike, and while it may not be totally necessary for all riders, the 170mm stroke dropper post is fashionably long for such a short travel bike.

Suspension & tyre setup

With the anodised sag gradients on the fork and shock, suspension setup is made easy. Weighing 80kg loaded up, Ben’s been running 180psi in the rear shock (26% sag) 80psi in the fork (20% sag).

The factory rebound tune for both the RockShox SID fork and Deluxe shock is quite light, so each rebound dial was set a couple of clicks slower than halfway.

Tubeless rim strips and valves come pre-fitted to the Bontrager wheels, and Trek kindly includes two bottles of sealant with the bike, making tubeless setup the breeze it should be. Pressures were set at 20psi on the front and 22psi on the rear.

Trek Top Fuel weight

Given its swollen proportions, the new Trek Top Fuel has gotten heavier. With the tyres setup tubeless, our test bike came in at 12.88kg without pedals. To put that number into perspective, here’s how it compares to some similarly-priced XC and Trail bikes we’ve recently tested;

• Canyon Lux Trail CF 9 – 11.22kg
• Merida Ninety-Six 8000 – 11.63kg
• Scott Spark 910 – 12.43kg
• Specialized Stumpjumper Pro – 12.84kg
• Trek Top Fuel 9.8 XT – 12.88kg
• Giant Trance Advamced Pro 29 1 – 13.38kg

Trek claims a carbon Top Fuel frame weighs 2.7kg including the rear shock, which puts it on the heavier side of things for a 120mm travel bike. The alloy frame is purportedly a whole kilo heavier again, with a claimed weight of 3.74kg.

The Top Fuel’s rolling stock is also a significant contributor to its overall mass. The Bontrager Line Elite wheels are heavy at 2,071g for the pair (with tubeless strips and valves). Incidentally, these are exactly the same wheels that came on the Slash 9.9 X01 , which is a full-bore enduro race bike.

Trek has also plumped up the rubber. The previous Top Fuel featured semi-slick XR3 tyres, but the new bike is now spec’d with 2.4in wide XR4 Team Issue tyres. They’re not overly heavy at around 800g each, though they do offer significantly better grip across a broader range of conditions.

What does the Trek Top Fuel do well?

From the very first ride the new Trek Top Fuel proved to be easy to get used to, with no quirks to the fit, handling or suspension.

The proportions are significantly broader compared to the outgoing Top Fuel, with the front wheel sticking out much further ahead of the rider. Despite the long reach however, the effective top tube length is basically identical to its predecessor, so the overall cockpit length remains the same.

The steeper seat angle is noticeable though, providing an improved climbing position with your hips placed further over the bottom bracket. As a result, less bum-shuffling is required on stem-chewing ascents.

Pedalling performance is also superb. Despite its burlier exterior, Trek is still prioritising pedal efficiency with the Top Fuel, with the main pivot positioned high and quite far forward of the bottom bracket. Anti-squat is claimed to hover around the 100% mark, and indeed the rear suspension clenches tightly under chain torque, propelling the whole bike forward with minimal energy loss.

Active suspension performance

Despite the trunnion bearing mount and the longer shock stroke, the rear suspension doesn’t feel radically plusher than its predecessor, which already offered great performance. It is noticeably more supportive though, particularly when absorbing square-edge hits at speed, and when returning to earth after boosting off a lip on the trail.

It’s worth noting here that many bikes in the 100-130mm travel bracket make use of a carbon flex-stay design, including the Canyon Lux Trail, Merida Ninety-Six, and Specialized Stumpjumper. As well as being simpler, flex-stay designs are typically lighter too.

In comparison, the Top Fuel sticks with a genuine four-bar platform based around the ABP suspension design. Trek claims the ABP pivot helps to isolate braking forces from the suspension, and indeed it does result in less skipping and skidding when you’re on the brakes on loose, rocky descents.

With all the pivot points rolling on steel ball bearings, the suspension is more active and possesses a more consistent feel to both compression and rebound damping when compared to a flex-stay design. Yes it’s heavier, but the Top Fuel offers notably more active suspension performance, with excellent traction on loose climbs and better reactivity across chattery rock gardens. It’s very impressive for a 120mm travel bike.

Look out Fuel EX!

The geometry is also brilliant, and the handling really sets it apart from the outgoing Top Fuel.

Cornering performance has improved, with more grip courtesy of the longer front end and those XR4 tyres. These are great all-rounders, with a supple casing and surprisingly decent rolling speed given their size and tread pattern.

The new Top Fuel is also much more composed on rough and fast descents. Thanks to the longer reach and slacker head angle, the overall wheelbase length has grown by almost 40mm. That’s huge, and it offers a vastly more planted feel at speed. Along with the big tyres and active suspension, this really is a solid little trail bike.

In fact, the geometry updates kind of make the Fuel EX look a little outdated. The two bikes now share the same head angle, and the Top Fuel has a 10mm longer reach and a steeper seat angle. The front end is quite a bit higher on the Fuel EX though, and that does inspire more confidence on really steep descents.

As mentioned earlier though, it’s possible to fit a 130mm fork to the Top Fuel, which would lift the front end and actually make it slacker than the Fuel EX. Indeed there’s now quite a bit of overlap between the two platforms, leaving us to ponder what could be in store for the next generation Fuel EX.

What does it struggle with?

You’ve likely gathered that the new Trek Top Fuel is more of a muscly trail ripper than a spindly XC featherweight. While it may carry over the name, it’s evolved into quite a different bike compared to its racier ancestors.

The lack of a remote lockout results in a much cleaner cockpit, and we like how it signals the Top Fuel’s commitment to its trail riding intentions. However, it may disappoint those riders and racers who prefer having an instantaneous sprint button at their fingertips.

Indeed with all the updates, and the fact that the new Top Fuel has double the travel of the Supercaliber, there is now an even bigger gap between these two bikes. Riders who are still interested in some part-time XC racing, but aren’t sold on the Supercaliber’s sharp geometry and proprietary IsoStrut suspension design, may be turned off by the Top Fuel’s new attitude.

Of course you could easily inject some speed with some lighter and faster-rolling tyres, like Bontrager’s XR2. There’s also around half a kilo to be saved in the wheelset, which would make a significant difference to the Top Fuel’s acceleration and climbing enthusiasm.

You could also flip the Mino Link into the High position to steepen the angles. In that guise, with lighter wheels and faster tyres, the Top Fuel would make for a comfortable and confidence-inspiring option for those wanting to sign up for the odd endurance race or multi-day event. If you’re serious about your XC racing though, this is not the bike for you – you’ll be wanting to look at the stupendously efficient Supercaliber for such endeavours.

Component highs & lows

The 2022 Trek Fuel 9.8 XT is a solid package out of the box, especially when you consider it comes in $1,600 cheaper than the 2021 model. And that’s with a pretty much identical build kit. How has a new bike gotten cheaper in the midst of a global pandemic and industry-wide component shortages? Heck knows!

There’s not a lot to be said about the Shimano XT groupset – it works, it’s solid, and it’s easy to tune. The I-Spec mounts offer plenty of adjustability for getting the brake and shift levers into the right spot, and the integrated dropper lever is a nice touch too.

The RockShox suspension isn’t quite as sensitive as the Fox equivalent, particularly the SID Select+ fork, which felt a little stickier than we expected. Otherwise the fork and shock perform well, and the ease of setup is great.

The Bontrager dropper post works fine, but the action is sluggish compared to some of its competitors. And while the carbon handlebars offer a nice profile, having spent a lot of time on OneUp handlebars lately, the Bontrager Line Pro feels considerably harsher in comparison.

We’ve had excellent long-term experience with Bontrager’s latest Line Pro & Line Elite carbon wheels , which feature thick carbon beads that are designed to increase impact strength while also reducing the chance of pinch-flats. They’re totally solid and come with an excellent crash-replacement guarantee, while the buzzy 108pt engagement freehub delivers rapid pickup at the pedals. As mentioned earlier though, they are heavy, providing an opportunity to drop significant weight with a wheel upgrade.

Otherwise we’ve been impressed with the frame finish so far. The Mino Link is simple and effective, the Knock Block is totally unnoticeable on the trail, and we’re big fans of the built-in storage from the Burrito Box. Or is it the Kebab Cave? Maybe a Sausage Roll Hole? Sushi Shaft? Cannoli Cavity? Hot Dog Hollow? Spring Roll Room?

Alright, alright! We’ll show ourselves the door…the door that leads into the Spring Roll Room – ha!

Flow’s Verdict

Tying together a whole suite of updates to the frame and suspension design, there are no doubts that the new Trek Top Fuel is a more capable bike than its predecessor. It’s still very efficient, but having adopted a more progressive approach to its geometry, it delivers a significant improvement in stability. Along with the active ABP suspension design and chunky tyres, there’s an exceptional amount of grip and support on offer for a 120mm travel bike.

With all those changes, the Top Fuel moves even further away from the Supercaliber. And for some riders, that gap will be a little too wide.

Trek seems happy to have a clear delineation between the two platforms though. This differs from some other brands that utilise a single frame, and simply up-fork and up-shock it to create a slightly longer travel bike (like the Specialized Epic EVO and Orbea Oiz TR). The Top Fuel is not one of those bikes.

Instead of being a long-legged Supercaliber, it’s really a shrunken-down Fuel EX, albeit one with more contemporary geometry. And having ridden both bikes, unless you really need the extra travel of the Fuel EX, this is arguably the better option.

Sure it may have put off the weight-weenies and lockout-lovers, but there’s no denying that the Top Fuel has broadened its appeal to an even wider range of riders, and we reckon it’s more fun as a result.

2022 Trek Top Fuel 9.9 XTR

• Fork | Fox 34 Step-Cast, Factory Series, FIT4 Damper, 44mm Offset, 120mm Travel
• Shock | Fox Float DPS, Factory Series, 185x50mm
• Wheels | Bontrager Line Pro 30, OCLV Carbon Rims, 29mm Inner Width
• Drivetrain | Shimano XTR 1×12 w/e*thirteen TRS Race Carbon 30T Crankset & 10-51T Cassette
• Brakes | Shimano XTR Race 2-Piston w/Ice Tech Rotors
• Bar | Bontrager RSL Integrated, OCLV Carbon, 27.5mm Rise, 820mm Width
• Stem | Bontrager RSL Integrated, OCLV Carbon, Length: 35mm (S), 45mm (M-XL)
• Saddle | Bontrager Arvada Pro, Carbon Rails
• RRP | $14,199 AUD

2022 Trek Top Fuel 9.7

• Fork | Fox Rhythm 34, GRIP Damper, 44mm Offset, 120mm Travel
• Shock | Fox Float DPS, Performance Series, 185x50mm
• Wheels | Bontrager Line Comp 30, Alloy Rims, 29mm Inner Width
• Drivetrain | Shimano SLX/XT 1×12 w/Deore 30T Crankset & 10-51T Cassette
• Brakes | Shimano SLX 4-Piston
• Bar | Bontrager Line, 27.5mm Rise, Width: 750mm (S), 780mm (M-XL)
• Stem | Bontrager Elite, 45mm Length
• Seatpost | TranzX Dropper, 34.9mm Diameter, Travel: 100mm (S), 150mm (M-M/L), 170mm (L), 200mm (XL)
• Saddle | Bontrager Arvada, Steel Rails
• RRP | $6,299 AUD

2022 Trek Top Fuel 8

• Frame | Alpha Platinum Alloy, ABP Suspension Design, 120mm Travel
• Fork | RockShox SID, Rush RL Damper, 44mm Offset, 120mm Travel
• Brakes | Shimano Deore 4-Piston
• RRP | $5,299 AUD

2022 Trek Top Fuel 5

• Fork | RockShox 35 Silver RL, Motion Control Damper, 44mm Offset, 120mm Travel
• Shock | X-Fusion Pro 2, 185x50mm
• Wheels | Bontrager Alloy Hubs & Alex MD35 Rims
• Drivetrain | Shimano Deore 1×12 w/Deore 30T Crankset & 10-51T Cassette
• Brakes | Shimano MT200 2-Piston
• Bar | Bontrager Comp, 15mm Rise, 750mm Width
• Stem | Bontrager Rhythm Comp, 50mm Length
• Seatpost | TranzX Dropper, 34.9mm Diameter, Travel: 100mm (S), 150mm (M-M/L), 170mm (L-XL)
• RRP | $3,499 AUD
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Field Test Review: 2022 Trek Top Fuel - Same Name, Different Bike

Cool Features

Gear-obsessed editors choose every product we review. We may earn commission if you buy from a link. How we test gear.

Tested: Trek Top Fuel

Don't call it a race bike. Trek's new Top Fuel is for railing steep fast decents with no course tape in sight.

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.

Price: $11,500 Weight: 26.8lbs (size XL) Style: Full suspension 120mm trail bike Frame: 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: 29” Fork: 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 Drivetrain: SRAM Eagle AXS, wireless, 12-speed Cranks: SRAM XX1 Eagle, DUB, 55mm chainline, 175mm length Chainring: 30 tooth Cassette: SRAM Eagle XG-1299, 10-52T, 12-speed Brakes: 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'' Saddle: Bontrager Arvada, austenite rails, 138mm width Seatpost: 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

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.

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.

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.

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.

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’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.

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.

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.

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

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Trek Top Fuel 8 review: a progressive rather than podiuming XC machine

Trek’s top fuel delivers superlative short-travel suspension performance but it’s definitely a trail bike not an xc bike.

BikePerfect Verdict

Awesome suspension, agile swagger, grippy kit and practical frame updates build a brilliant rally bike, but high weight buries any XC aspirations

Infectiously agile and playful vibe

Superlative suspension feel

Seriously tight tracking frame

Trail tough kit

Internal storage

Too heavy for XC racing

Simple fork damper

Tight internal storage access

Yawning gap between this and the Supercaliber

Why trust BikePerfect Our cycling experts have decades of testing experience. We'll always share our unbiased opinions on bikes and gear. Find out more about how we test.

Top Fuel used to be Trek’s out-and-out best full-suspension mountain bike for racing, but with the soft-tail Supercaliber under its sponsored riders now, the Top Fuel has developed a burly rather than race character. 

The latest frame, suspension and spec changes to the 8 make the most of its short-travel agility and gripped tenacity to create a proper rally racer. Excess weight shows on climbs and acceleration though.

Design and geometry

The alloy Top Fuel frame not only has the same geometry, shock and suspension layout as its carbon counterpart but Trek’s engineers have also worked super-hard to give it the same extensive, updated feature lineup. That includes the lever-locked trapdoor into the down tube for internal storage, threaded bottom bracket shell with chain guide tabs. The Knock Block 2.0 inset now allows 72-degrees of steering lock (not 58-degrees as before) or you can fit a blank insert for full rotation if the bars aren’t slammed. 

In fact, it’s one of those bikes where we continually found ourselves riding how we always want to ride, not how we actually ride. That inevitably builds into an addictive upward spiral of confidence and insolent speed that often ended with us snapping at the heels of more expensive longer travel bikes even on really rowdy trails. Picking a larger, longer frame will settle it even more at speed, but for flow trails, it was refreshing to really rip those big Bontrager side tire lugs round on a compact, close combat chassis. Just be careful you don’t get too carried away, as however good it feels, less travel inevitably means the tires are having to cope with more impact force and we soon put a couple of splits in the rear tire despite the ‘inner strength’ casing.

When that happens the narrow neck of the storage hatch can make getting your spare tube out awkward and the high cage position means you won’t get a large bottle in either. There’s space for a 2.5in tire in the rear swingarm which pivots co-axially around the rear axle according to Trek’s ‘Active Braking Pivot’ wisdom. While it limits choice, the switch to a 34.9mm seatpost size should mean stiffer, smoother dropper action, especially on larger frame sizes which get up to a 200mm shaft stock. The new trunnion style shock pivots more smoothly and is the right way up now compared to last year’s inverted shocks. That means the MinoLink geometry flip chip to change angles by 0.5-degrees is now at the base of the shock but it’s still easy to get too. Significantly all RockShox spec Trek bikes from the 8 upwards get the same ‘Ultimate RCT’ spec Deluxe rear shock.

The alloy frame is a kilo heavier (3.74kg vs 2.7kg) than the carbon option according to Trek’s weights. This saves you $1,400/£1,500 if you buy the frame separately, although it still retails for $2,319.99/£2,350. Those numbers prove it’s neither affordable or light for a bike that you’ll find listed in the XC section of Trek's website, not the trail pages. In fact, the 130mm Fuel EX Al frame is the same weight although that doesn't have internal storage.

A 66/66.4-degree head tube definitely suggests progressive riding rather than traditional podium hunting vibes too. The 465/469mm reach on our M/L size is more trad than rad though so riders after a stretch should make use of the short 450mm seat tube and opt for the L with a 480/484 reach. All bikes get the same 76/76.4-degree seat tube angle and 434/435mm chainstay length though so while having six (S-XXL) sizes is great, the balance is definitely centered around the M - M/L - L models.

Components and build 

The Top Fuel 8 is the most expensive alloy bike, above the 7 at $3,529.99/£3,200 and the 5 at $2,629.99/£2,700 (we don’t know what 6 did to offend them but its missing from the line-up), but below the carbon-framed 9.7 at $4,229.99/£4,700.

The highlights of the package are the lightweight SID fork (albeit with the simplest Rush Damper) and Shimano XT rear mech and shifters. The Bontrager XR4 tires are some of our favorite welterweight all-rounders too. The SLX crank is a great piece with a 30T ring for easy climbing, but muscle Mary’s will find a 36T fits the frame too. You get a 150mm Trans-X dropper with a Bontrager Arvada saddle on top and 35mm diameter Bontrager Elite 45mm stem and 780mm wide bar.

Deore four-pot brakes just about do the job adequately via 180/160mm rotors but together with the wide rim tubeless Bontrager Line Comp 30 wheels they’re an obvious area where extra weight creeps in and adds up to nearly 14.5kg without pedals. 

Performance

Add that weight to chunky treaded, relatively grippy tires and however Trek categorizes the Top Fuel, the 8 clearly isn’t the best choice for charging climbs and ripping round simple XC laps. Now we’ve got rid of the people who’ll likely love the 12.2kg Trek Supercaliber for the same money, we can start talking about what the Top Fuel does do really well – and that’s riding properly rowdy.

While bikes like the Evil Following , Santa Cruz Tallboy , and Norco Optic have already established that short-travel bikes can feel awesome, the Top Fuel definitely goes into the small travel, BIG capability hall of fame. Like most of its peers, it doesn’t squander initial shock movement and can feel slightly sharp in the car park unless you drop tire pressures low. 

Once moving though it’s both amazingly fluid and connected over ruts and roots whether climbing janky tech or sucking onto stutter bump/root ripple turns or off-camber high lines. The wheel path and rear pivot position mean there’s minimal pull back through the pedals as it hoovers up chunder so you can stay on the gas without getting jacked or stalled out. While we’re always suspicious of acronyms and a 160mm rotor doesn’t generate much torque anyway, the braking performance of the ABP rear end is impressively grippy compared to the same hardware on other bikes. 

The RCT damper also has plus and minus low-speed compression settings to fine-tune support sensitivity depending on personal/terrain preferences. Even in the plus setting the mid-stroke mobility does mean you’ll want to flick into the much firmer ‘pedal’ mode if you’re stood up slow cadence churning on a climb or don’t want distracting bounce on long smooth climbs. The SID fork gets a similar firming option via the fork top lever though we rarely touched it unless we were really hanging on a road climb.

While the superlative suspension performance is definitely the heart of the Top Fuel’s ‘have a go hero’ character, the rest of the bike definitely exploits it rather than squandering it. The alloy frame might be heavy but it’s seriously stout when it comes to squaring up to the trail when things get punchy.

While the simpler Rush damper starts to get seasick and inconsistent well before the back end, the 35mm stanchions do a great job of staying on track. Shorter travel means less dive too and together with well-balanced cockpit dimensions and steering angle gives a really predictable and tenacious target lock.

Despite the hefty weight and relatively slow rear hub engagement the fact you can keep the power down or brake really late meant the Top Fuel always felt hyped to be hitting trails and tweaking lines as fast as possible. The shorter M/L size made it a proper joyride on tighter, twistier trails but you can still drive it really hard, heels down, feet level through turns and it loves to pump downslopes.

Trek’s Top Fuel 8 is a brilliant example of just how good short-travel suspension can feel, and less stroke always means a more responsive, visceral ride than a leggier bike. The geometry and proper trail tires really let you exploit the hooligan that’s hiding in the frame along with your pump, tool and spare tube too. 

As much as we’ve loved ripping around the trails on it, there’s no doubt it’s heavier and harder to accelerate/elevate than we’d like for its supposed XC/downcountry range placement though. If you’re about the overall vibe, not outright velocity, that doesn’t matter though.

Test conditions

• Temperature: -2 to 8 degrees
• Surface: Mixed blue-black trail center, moorland tracks, off-piste wooded tech and DH

Tech Specs: Trek Top Fuel 8

• Price: $3,829.99 / £3,850
• Model: Trek Top Fuel 8
• Discipline: XC/downcountry/trail
• Head angle:  66/66.4-degrees
• Frame material: Alpha Platinum Aluminium
• Weight: 14.46kg
• Wheel size: 29 x 2.4in 
• Suspension: RockShox SID 120mm travel, 44mm offset/RockShox Deluxe Ultimate RCT 120mm travel
• Drivetrain:  Shimano XT M8100 mech and shifter. Shimano SLX M7100, 10-51 cassette, chain
• Cranks:  Shimano XT 30T chainset
• Brakes:  Shimano Deore M6000 brakes with 180/160mm rotors
• Cockpit:  Bontrager Line 780mm bar and 45mm stem
• Wheelset:  Bontrager Line Comp 30 wheels
• Tires:  Bontrager XR4 Team Issue 29 x 2.4in tires
• Seatpost:  TranzX 150mm dropper post
• Saddle: Bontrager Arvada, steel rail saddle

Guy has been working on Bike Perfect since launch in 2019. He started writing and testing for bike mags in 1996. Since then he’s written several million words about several thousand test bikes and a ridiculous amount of riding gear. To make sure he rarely sleeps and to fund his custom tandem habit, he’s also penned a handful of bike-related books and talks to a GoPro for YouTube, too.

Current rides: Cervelo ZFS-5, Specialized Chisel, custom Nicolai enduro tandem, Landescape/Swallow custom gravel tandem

Height: 180cm

Weight: 69kg

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