Trek has pulled the covers off its redesigned enduro bike, the Slash. As expected, brand focused on bringing the Slash up to speed with modern frame angles, but along with the longer, slacker updates comes a long list of feature and component upgrades that make the Trek Slash more appealing to riders looking for a reliable partner for enduro racing, bike park laps and aggressive trail riding.

Related: Everything you need to know about the new Trek Slash

Trek Slash 9.9 Highlights

  • Full carbon frame
  • Revised geometry
  • 160mm rear / 170mm front travel
  • Adjustable geometry
  • 73mm threaded bottom bracket
  • Internal frame storage (on all models)
  • Price: $7,999
  • Weight: 32.5 pounds w/o pedals
  • Available now
  • Visit for more information

Back up to speed

Trek Slash 2021 Review:

Trek had their work cut out for them in updating the Slash. Since it's introduction in 2017, there have been significant changes in geometry and the Slash had some catching up to do.

The 2021 Trek Slash is neither the longest nor the slackest, in the category, but its 64.5 head tube angle, 76-degree seat tube angle, and increased reach measurements are a welcome refresh. Trek retained the geometry-tweaking Mino-Link for slight geometry adjustments to suit rider preference and terrain.

Trek Slash 2021 Review:

Trek's Mino link adjusts the head angle by .5-degrees and the bottom bracket height by 6mm.​

Going hand-in-hand with the updated geometry is an increase in suspension travel. Slash gets a bump in travel to 160mm at the rear and 170mm upfront. "More travel was a request from our riders. Our team riders were putting longer and longer forks on their bikes," said Dylan Howes, Trek's senior mountain bike engineer.

Along with the increase in travel comes a new shock. Trek worked closely with RockShox to develop a Thru Shaft version of the SuperDeluxe shock that balances sensitivity with an efficient pedaling platform. "We were hyperfocused on controlling rider input," said Jose Gonzalez, Trek's suspension director.

Trek and RockShox paid close attention to shaft speeds. According to RockShox' Chris Mandell, most rider inputs such as pedaling, pumping through turns, and weight adjustments result in relatively low shaft speeds (2-10 inches per second). At these speeds, the SuperDeluxe Ultimate provides a firm pedaling platform. Once shaft speeds increase above 10 inches per second, the compression circuit opens up and allows for unrestricted movement.

Riders can fine-tune this with the low-speed compression knob, which offers three levels of damping. Regardless of which level of compression adjustment riders choose, there's no impact on high-velocity performance. "The wheel will still move out of the way for rocks and roots that create greater shaft speeds," Mandell said.

Trek Slash 2021 Review:

Trek and RockShox worked together to develop a version of the SuperDeluxe Ultimate for the Slash.​

Trek Slash 9.9 ride review

Trek Slash 2021 Review:

The downtube box is a welcome addition to the Slash.​

On the trail, the Slash feels like a thoroughly modern enduro race bike. It handles extremely well once up to speed and is surprisingly playful. That's an aspect of the bike's personality I wasn't expecting. I also wasn't expecting this 32.5-pound machine to climb as well as it does.

Many 29ers in the 160-180mm realm pedal fine on fire road climbs, but feel like a burden on technical singletrack ascents. Even with steep seat tube angles, their long wheelbases, supple suspension, and overall heft can leave riders sapped of energy when it comes time to descend.

Whether you're racing an enduro or just want to be fresh and focused for the fun part of the ride, there's a lot to be said for the Slash's ability to climb efficiently. As advertised, the SuperDeluxe Ultimate shock does an outstanding job of damping rider inputs. I found the lightest of the three low-speed compression settings was perfect for the loose and rocky trails I ride. In this setting, the shock provided enough platform for efficient climbing without sacrificing sensitivity.

The surprises continued through the descents. On flowy and less demanding terrain, the Slash has an uncanny ability to hide its travel. Unlike many long-travel bikes tuned for descending, the Slash doesn't wallow in the mid-stroke or feel like the suspension is sapping energy when pumping through undulations and berms. The rear sits high in its travel and retains a poppy character more in line with shorter-travel trail bikes, like Trek's Fuel EX.

As speeds picked up and trails steepened, the SuperDeluxe continued to perform well, shrugging off impacts with ease-particularly repeated high-speed impacts, such as tree roots that stretch out like a latticework over the trail. While the Slash can accommodate a number of aftermarket shocks, the SuperDeluxe Ultimate really does make this enduro racer a much more versatile bike.

Trek Slash 2021 Review:

The SuperDeluxe Ultimate makes the Slash a good all-arounder.​

The geometry and overall demeanor of the Slash favor riders who want a well-rounded long-travel 29er. The Slash has the composure at speed that racers seek but, in spite of its heft, the Slash can navigate technical trails as a long-legged trail bike.

The Slash 9.9 is a well-appointed machine. The RockShox Suspension is an excellent match for the bike's personality, Bontrager's Line Pro 30 Wheelset proved itself stiff and sturdy, and the Bontrager carbon bar and dropper post performed without any complaints.

Related: Bontrager Line Pro 30 wheelset review

The downtube storage box is a great addition, though the amount of gear (or food) you can store on it will vary with frame size. (Longer downtubes mean more storage.) On my size medium tester, it was a struggle to fit a 29er tube, CO2 with inflator, and tire lever into the downtube.

In my opinion, the one area where Trek's product team stumbled was in opting to spec 175mm crank arms on the Slash. This seems like a serious oversight when nearly all of its counterparts such as the Specialized Enduro come equipped with 170mm crankarms. Many many amateur and professional enduro racers run 170mm or even 165mm crankarms as well. Admittedly, crank length is a personal preference, but this is a misstep on an otherwise well-thought-out bike.

Trek Slash 2021 Review:

Knock Block 2.0 offers riders a much wider steering range.​

One feature that irked me on previous Trek mountain bikes was thankfully invisible while riding the Slash. Trek's second generation of the Knock Block system, designed to prevent the brake lines from pulling out and handlebars from contacting the frame during a severe crash, has a much wider range of movement.

Knock Block 2.0 allows for 144-degrees of bar rotation (72-degrees per side), that's 28-degrees more (14-degrees per side) than the original system. This additional range of motion was enough to navigate tight, low-speed switchbacks without impeding steering.


The Slash is back up to speed for enduro racing with improved geometry and smart frame features, but it's the RockShox SuperDeluxe Ultimate shock that makes the Slash such a versatile machine. The Slash climbs much better than similar long-travel 29ers. This is thanks to the ability of the shock to mute rider inputs and provide an efficient pedaling platform that doesn't take away from traction or sensitivity when speeds pick up. If you're looking for a long-travel 29er that's more than a one-trick race pony, the Slash will oblige.