The Trek Top Fuel Finds Trail Religion and Is Reborn as a Fun Trail Bike
The takeaway: You can ride all day without sweating the climbs.
Reborn as a trail bike, the new Top Fuel has more travel and is more stable.
Complete builds come with dropper posts and other trail-oriented parts.
Aluminum frame Top Fuels start at $3,300. The most expensive carbon model is $10,000.
Weight: 24 lb. (9.9, size small)
Throughout its life, Trek's Top Fuel was the brand's cross-country racing bike. That purpose changes with the introduction of the 2020 Top Fuel. It's now a fast trail bike, and shares a lot with bikes like the Yeti SB100, Santa Cruz Tallboy/Juliana Joplin, and the Spot Ryve 115. Trek's product team shifted almost everything towards more of a trail bike build, giving it more travel, progressive geometry, and heartier parts. The result is a beefier bike that’s super fast and light, making it perfect for both endurance and trail riding.
—Five Great Details—
From Cross Country to Trail Bike
While the 2019 Top Fuel featured 100mm of travel in the front and back, the new Top Fuel now has 120mm of front suspension and 115mm of rear suspension. They’ve also done away with the floating mount that compressed the shock from both ends. Instead, the lower eyelet is fixed to the downtube, a change that reduces weight and improves stiffness.
Tires are also trending wider across the industry, and the same proves true here. Instead of light and skinny race tires, the new model comes with 29x2.40-inch Bontrager XR3 Team Issue tires designed for a variety of riding conditions. The new Top Fuel 9.9 also has armor to protect the downtube against rock strikes and Trek's Knock Block headset which prevents the bars and fork from twisting backward and damaging the frame.
As for geometry, the new model is slacker and longer than the last, and it has a shorter stem and wider bars than the previous generation. One of the most notable changes, however, is the updated front suspension offset. Trek was arguably the first to get behind an increased offset—specifically 51mm—for their 29ers.
Other brands eventually followed and soon most 29ers were using 51mm offset forks. But the current trend of longer front centers and slacker head angles has reversed this tide, and the offsets are shrinking. Even Trek couldn't fight the reduced-offset trend: the new Top Fuel uses a 44mm offset fork.
All the Bells and Whistles
As a top-of-the-line 9.9 model, our review bike comes with everything you’d ever want on an endurance bike and then some. Last year’s Top Fuel family didn’t feature a single dropper post, but now, every model comes with one. The small starts with a 100mm dropper and from there dropper sizes run all the way up to 170mm on the largest sizes.
The left handlebar grip features a TwistLoc remote that lets you lock out both front and rear suspension with one simple twist. Unlocking it is even easier, you just push a small button with your thumb. I was warned about it prior to riding, to prevent me from accidentally triggering it, but I didn’t find that to be a problem at all. Maybe it’s my small hands, but I think you really have to activate it intentionally. However, near the end of the review period the fork's lockout mechanism began to stick and sometimes wouldn't open.
The bike also comes with Trek’s Mino Link, which is located on the front of the rocker, making it easier to access and change than on previous versions. In the high position, the 9.9 has a quicker-steering vibe. If you want a more stable feel, flipping it to the low position will drop the bottom bracket 8mm, and relax the head angle from 68 to 67.5 degrees.
Right now the Top Fuel 9.9 comes in two color options: All black matte (for those minimalists) or an eye-catching black and teal hybrid with neon green lettering seen here. If you’re thinking of getting the Top Fuel and really want to go all out then you might want to wait until July 25, when the new Top Fuel joins Trek's ProjectOne customizable paint and build program.
You get all of these features, and the bike still only weighs 24 pounds (size small). The only thing the Top Fuel 9.9 doesn’t come with is electronic shifting. For that you’ll want the $10,000 Top Fuel 9.9 AXS with SRAM's Eagle AXS wireless group.
Frame: Carbon
Wheel Size: 29-inch
Travel: 115mm
Shock: Fox Factory Float
Fork: Fox Factory 34 Step-Cast, 120mm
Drivetrain: 1x12
Crankset: SRAM XX1 Eagle Carbon, 32t
Rear Derailleur: SRAM XX1 Eagle
Cassette: SRAM XG-1295 Eagle, 10-50
Brakes: SRAM Level Ultimate hydraulic disc, 180mm front/160mm rear rotors
Seatpost: Bontrager Line Elite dropper, 100-170mm travel
Rims: Bontrager Kovee Pro 30 carbon, tubeless ready
Tires: Bontrager XR3 Team Issue 2.4 in., tubeless ready
Sizes: S, M, M/L, L, XL
The Top Fuel Family
If this $9,000 9.9 falls outside of your budget, there are three other bikes in the Top Fuel family that you can get for less.
The family starts with the Top Fuel 8 at $3,300. It’s the only aluminum bike in the line-up, and it weighs almost 30.5 pounds (size medium, claimed). It comes with the same amount of travel, a SRAM NX Eagle drivetrain, and you’ll even get the TwistLoc remote. For $4,000, you can get the Top Fuel 9.7. You’ll get roughly the same set up as the 8 but with a full carbon frame.
The Top Fuel 9.8 comes in at just over 26 pounds (claimed) for $5,500. You’ll get better components like SRAM GX Eagle, the Bontrager Line Elite Dropper (like the 9.9), and a Fox Performance 34 fork and Bontrager Kovee Elite 30 wheels with carbon rims.
The the 9.9 and the 9.9 AXS get Bontrager Kovee Pro 30 wheels with 108-tooth Rapid Drive hubs, for near-instant engagement. At $10,000, the biggest differences between the 9.9 and the 9.9 AXS are the wireless SRAM Eagle AXS shifters and the wireless RockShox Reverb AXS dropper.
Reshuffling the Trek Full-Suspension Family
Trek has a number of world-class cross country racers on its mountain bike teams. With the Top Fuel no longer a race bike, those riders will need a new XC bike. And it appears one is coming soon. Trek's racers are aboard a new bike with a sock on the top tube covering up a new full suspension design.
With its new trail orientation, the Top Fuel has serious overlap with Trek's current Fuel EX, a 130/130mm trail bike. We expect that will be rectified with a new version of the Fuel EX that will launch later this year. It will likely have more travel than the current Fuel EX, as well as longer geometry, slacker headtube angle, steeper seat angle, a shorter offset fork, a stiffer frame, and will be built with heartier parts.
How It Rides
I took the new Top Fuel to the trails I'd been riding on my personal Trek Fuel EX 5 — a heavier and longer travel bike than this Top Fuel 9.9. The trails I rode during the initial test ride were flowy, with a few technical spots and long climbs.
The biggest thing I noticed? Climbing wasn't nearly as difficult as it was on my personal bike. I wouldn't call it effortless, but the difference was significant. Riding in the "cross country" setup, with the Mino Link set high and the stem flipped in the downward position, the Top Fuel is a quicker steering and faster feeling trail bike. In this form, the bike truly would be great for endurance races like the Breck Epic and BC Bike race.
In the low mode, the bike feels mellower, but still a fast and agile bike. On paper, it has a lot in common with the Yeti SB100 and Santa Cruz Tallboy, which puts the new Top Fuel in very good company.
Taking it on some rocky trails, the Top Fuel tackled them just as well. While it might not have as much suspension as other trail bikes, it can just as easily rip down most technical trails. The 29er wheels and wider tires help the bike roll over obstacles with ease, without taking away from the bike's superb climbing ability.
The new Top Fuel might not be a pure XC-race bike anymore, but it's still precise and very fast. Its new trail orientation makes it a great choice for a rider who wants a fast and light bike with most of the the efficiency of a cross-country race bike, but with bit more versatility and playfulness.
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