Trek’s Fourth-Gen Top Fuel Is a Dream on the Trails

The new Top Fuel hardly puts a tyre wrong and is up for any kind of riding, from light enduro to XC stage races.


BY MATT PHILLIPS |

Voted ‘Fastest Trail Bike’ in the 2025 Bike Buyer’s Guide currently on sale

The Top Fuel was Trek’s premier full-suspension XC race bike several years ago. But starting in 2019, Trek began to transform the Top Fuel into a lightweight trail bike – bumping up the travel and relaxing the geometry, but keeping some XC features, such as the remote lockout.

The third-generation Top Fuel was launched in 2021, with more travel (120mm rear and 120mm fork), even more relaxed geometry, in-frame storage, and no more remote lockout. But 2021 was also when some brands began to debut XC race bikes with 120mm travel and slacker geometry, in response to rowdier courses. 

Trek, however, went a different direction, and debuted a new, shorter-travel full-suspension Supercaliber for XC racing. As a result, the third-generation Top Fuel quickly found itself in a sort of no bike’s land. It was intended, designed and equipped as not-an-XC race bike, while XC race bikes from competitors were arriving with travel and geometry very similar to those of the Top Fuel.

So with the next iteration of the bike, Trek began shipping the Top Fuel with a 130mm fork. This pushed it more into the trail bike category, and helped place daylight between it and the new-school XC race bikes.

Which brings us to today. For the fourth-generation Top Fuel, Trek has retained the 120mm rear/130mm front combo, while building in other refinements to make the bike more broadly versatile as a do-anything machine.

Trek Top Fuel Gen 4
Photo: Matt Phillips

For many years, Trek’s mountain bikes have featured a geometry-adjusting flip chip called Mino Link, and some of its more recent mountain bikes have a flip chip that makes the suspension more or less progressive. In the new Top Fuel, Trek combined the two flip chips into one four-position chip that alters geometry and progression in tandem. It’s a feature likely to make its way into more Trek mountain bikes in the future.

Other amendments include more anti-squat, which should make the bike feel slightly crisper when pedalling, and better in-frame storage with improved sealing – a larger opening in the down tube and some refinements to the routing tubes, so the storage bags slide in and out more easily.

The in-frame storage of the new Trek Top Fuel

The 120 rear/130 front (ish) ‘downcountry’ category the Top Fuel resides in is full of amazing bikes. Think of the Specialized Epic 8 EVO, the Giant Trance and the Santa Cruz Tallboy, for example. But the Top Fuel deserves its place among such illustrious company. 

The expectation for this style of bike is that it must be as fast on climbs as an XC bike, and allow the rider to go full send on descents like a trail bike. That’s impossible. So, while everyone is certainly seeking this holy grail of speed and capability in one, many bikes lean one way or the other. For example, the Epic EVO is more XC, while the Tallboy is more Trail.

The rear suspension of the Trek Top Fuel Gen 4 is tuned very well.
Photo: Matt Phillips

The Top Fuel, however, feels more equalised. It doesn’t climb like an XC bike and descend like a trail bike – again, impossible – but it doesn’t seem to lean one way or the other either. It feels balanced: equal parts quick and capable. 

This means nothing particularly stood out about the Top Fuel’s handling as I climbed and descended. It felt… normal? I wasn’t fighting the bike, and didn’t feel I needed to adjust to work around any quirks. It worked its way through my tightest, steepest climbing trails well, and handled downhill corners of all varieties intuitively. It flew true as an arrow on the fastest straightaways, yet I could change direction at will and with little resistance. 

I was lucky enough to test the top-tier 9.9 X0 AXS model (R230 000 – oof), but the carbon range starts with the Top Fuel 8 (R75 000) and all the bikes offer similar handling and performance, with the obvious weight trade-off. 

Overall, the Top Fuel Gen 4 is an excellent light trail bike/downcountry bike/burly XC bike (call it what you want) that can compete with the best on the market.

R230 000 / trekbikes.com

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