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TGR Tested: 2021 Trek Slash 9.9

Trek's new Slash 9.9 might be as aggressive as single-crown bikes get, but it's also a versatile tool that will make a good rider feel like a great rider in just about any kind of terrain. | Max Ritter photo.

There are few things that can bomb down a trail like a long-travel 29er. When Trek described the new Slash as “monster truck meets magic carpet,” it sounded like their marketing team had gone a little COVID-crazy, but I’ll admit it was seriously intriguing. I mean, if anything’s going to inspire confidence on a steep, scary trail, a monster truck seems to be a pretty safe bet. When I hopped on the 2021 Slash 9.9 last fall, I was ready to try some extra speed on for size. But I had no idea just how much it would change my riding.

To be perfectly honest, watching Casey Brown throw massive whips on her Slash made me wonder whether I could step up to the challenge of a bike like this. As an advanced (not expert) rider, I thought it might be too much bike for me. It’s built to go fast, like really fast. But despite the fact that this beefy 29er accelerates like a bat out of hell, the stable feel, easy handling, and ability to smoothly sail through technical terrain make high trail speeds alarmingly comfortable.

This bike, like most enduro bikes, is definitively marketed as a Bro Bike. There’s a whole separate issue within the bike industry to unpack there, but I think one of the most remarkable parts of the Slash is that despite its intimidating stature, it’s a friendly, manageable bike that can turn any good rider into a great one. Sure it’s a bike for racing to the EWS podium and it’s certainly proven its worth in that realm, but it’s also a versatile tool that can nudge an advanced rider onto terrain that might otherwise seem impossible.


Over the last few years, the Slash had remained pretty unchanged, but the 2021 Slash 9.9 has a few significant updates that boost the downhill-charging prowess as well as climbing capabilities. This year, following the greater trends of the industry, Trek updated the geometry with a slacker head tube angle (64.1°), steeper seat tube angle (75.6°), and a longer reach (469mm). Trek’s Mino Link technology allows you to adjust the geometry by 0.5° to put it in the “high” setting, but I did most of the riding in the “low” setting which comes stock, so these numbers reflect that. Trek also upped the fork travel by 10mm with a 170mm RockShox ZEB Ultimate fork, and the decently long 1243mm wheel base (on the M/L) provides a super stable feel at high speeds. Extra cushion and the slacked out geometry give the Slash that extra edge for a monster truck feel on the descents, while the steepened seat tube angle makes pedaling uphill feel remarkably efficient for a bike this big. Compared to previous Slashes, which fell a little more into the “trail” category than the “enduro” category, Trek is now fully embracing the trend of bikes designed for all-out speed.

5,000 vertical foot descents at high speed? The Slash says "yes please." | Max Ritter photo.

I tested a medium/large Slash 9.9 XO1, which was a welcome addition to the size run; at 5’8” a medium is often a little small and a large feels colossal for me, so the medium/large was ideal for a more precise fit. The 9.9 XO1 comes with a race-ready SRAM Eagle X01 drivetrain and SRAM Code RSC brakes, with an updated Knock Block 2.0 integrated headset that prevents the bars from spinning and ripping out your cables if you wreck. The new Knock Block 2.0 technology allows for 72° of clearance instead of the previous 58° for less impeded steering—in short, you probably won’t really notice it. I ended up cutting down the Bontrager Line Pro handlebar since 820mm felt pretty wide, especially considering the fact that the über-wide bar it’s specced on the small bike. Ultra-fast acceleration is thanks to the 29-inch Bontrager Line Elite 30 carbon wheels with a 54-tooth Rapid Drive hub, a lightweight and not-too-stiff wheelset that contributed to the overall smooth and responsive feel of the Slash.

The Slash 9.9 XO1 comes with a carbon frame, as does the 9.8 and 9.7, but the bike also comes in an aluminum option (Slash 7 and 8) with identical geometry (the previous Slash differed slightly in geometry between the carbon and alloy frame). The 9.8, 9.9, and 8 models all come with the new RockShox Super Deluxe Ultimate shock with the Thru Shaft damper, a proprietary model that Trek and RockShox crafted for a smooth and supple feel - a feeling more akin to a coil shock with the light weight of an air shock. The high speed compression lever has two modes—open or closed—which I use quite a bit for fire road climbs and smooth climbing trails. The position of the shock is just far enough away that it’s tough for me to reach the lever while pedaling, but someone with longer arms could probably get away with doing it along the trail. The low speed compression dial features a plus, zero, and minus setting, for versatility on different types of trails. Zero is a happy medium that most riders will run day in and day out, while Plus increases the stiffness for pedaling efficiency and response while pushing through berms and jump trails. The Minus setting lets the shock compress more freely, which I’ve opted for in steep, rough terrain where I want every bit of cushion I can get. After spending the better part of the season on the bike, I do think a lighter shock tune would be appropriate for riders like me, that weigh under 130 lbs. 

Trek’s Active Braking Pivot (ABP) technology is on all their full-suspension mountain bikes, but is worth mentioning since it contributes to the smooth feel over rough, gnarly descents. Instead of letting the rear end get locked up while braking, ABP separates the braking forces from suspension forces so the shock can move freely even while braking. It was super noticeable for me while plowing down relentlessly rough terrain in Idaho’s Silver Mountain Bike Park this spring, and kept my back tire grounded even when I felt like I was holding on for dear life.

Trek's Active Braking Pivot combined with the ThruShaft-equipped Rock Shox Super Deluxe give the Slash's rear end limitless traction, no matter how rough the trail gets. | Max Ritter photos.

Internal storage doesn’t have anything to do with how it rides, but it deserves a call out since it’s one of those features you don't know you need until you have it. It’s incredibly convenient for short pedals and shuttle rides where I don’t want to carry a pack, and fits a surprising amount of snacks if you take the flat kit out. The beefed up down tube guard adds a little extra protection for the frame while shuttle riding, which is another nice touch if you plan on beating the crap out of your bike.

The medium/large Slash 9.9 XO1 weighs in at 31 lbs, not the lightest you’ll find, but decently svelte for the incredible downhill performance you’re getting out of it.


The Slash wants to go fast, whether you want to or not. 30mph seems to be the Slash’s happy place, which isn’t usually my happy place, but this bike has gradually warmed me up to it.

When I hopped on the bike last fall and took it for a spin at Washington’s Tiger Mountain I was impressed by how immediately friendly it felt. It wasn’t the bucking bronco I’d hyped it up to be, but instead allowed me to glide over steep root sections I’d been stuck on for months and plow through rock gardens I’d been slowly picking my way through just a few weeks prior. Although it craves speed, the Slash does a remarkable job disguising it; almost every ride I’m alarmed to discover how fast I’ve truly been riding. If it were up to the Slash (and not my survival instincts), this bike would come without brakes entirely. You know when people say they’ve found their bike’s speed limit? I'm happy to report that I'm pretty sure the Slash has none.

Let's call the Trek Slash a long-travel adventure bike - because it's hungry for big days through the most unforgiving terrain. | Max Ritter photo.

It’s responsive at high speeds, and although it feels super planted and stable when maching down gnarly tech, it’s got a springy and energetic feel that’s a blast to ride flow trails. Riding Phillips Canyon, one of my favorite fast tech trails on Teton Pass, I was impressed at just how smooth so many of the rock gardens felt while riding the Slash. It handled speed with so much composure that I was shocked to have dropped 30 seconds off my last ride time. Later that week, I hopped on lifts at Jackson Hole’s Bike Park and enjoyed the bike’s lively character when boosting off jumps and whooshing through the impeccably maintained berms - proving that the Slash isn’t just a one-trick pony.

For a bike that can rip bike park laps like a downhill bike, climbing is surprisingly easy. The 29-inch wheels chew up technical climbs, and the steeper seat tube angle kept my body position centered which made it easy and comfortable to settle into longer climbs. I love big adventure rides, and I was nervous about climbing 3 - 4,000 feet at a time on such a burly machine, so I’m psyched about the efficiency of climbing on this thing. During a big pedal day at I-90’s Raging River area, I never felt the bike working against me during back to back 2,000-foot climbs, and it was a treat to drop into rooty downhill trails like Canyon Creek DH and No Service on this beast. Even during the occasional bike push or downed tree maneuver that’s conducive with spring riding in the Tetons or the Colorado High Country, it never felt too bulky to get it where I needed to go.

Checking off classic hits on the home trails. | Max Ritter photo.

When riding steeps, the quick acceleration took a bit to get used to. On steep, rutted trails like those found in the PNW where I felt like I needed to precisely control my speed, the Slash’s hunger for more worked against me a bit, and forced me to be a bit more strategic with my braking. Despite the relatively long rear end, the only real drawback I noticed was that it was easy to get thrown back a bit in tight corners if I got a little lazy and didn’t stay centered. In tight terrain where I was looking to be precise, it sometimes felt difficult to maneuver the bike due to the long wheelbase and quick acceleration, but the forgiving nature of the Slash’s geometry made it so that if I missed a move, I’d just keep plowing through without consequences. The only time it really feels clunky is on mellow rolling terrain that’s not quite as generous with its gravity, but that’s not the kind of terrain you’d buy this bike for anyway.

One thing to note: as with any bike, make sure your bolts are tight and threadlocked if necessary. On a weeklong trip through Colorado, the Mino Link geometry-adjust bolt and nut rattled itself loose, causing the flip chip to fall out and disappear forever. Luckily, it’s only a $6 part from a Trek dealer and a one-minute fix, but it was a bit of a headache to source the part.

The Bottom Line:

In short, the Slash is a friendly beast, one that I think any freeride or enduro racing-oriented rider will quickly fall in love with. For the areas I’ve been riding in (Tetons, Utah desert, Colorado high country, and Pacific Northwest) which feature big climbs, gnarly descents, and frequent bike park laps, the Slash is my ideal daily driver.

The caveat? You’ve probably been waiting for this: the Slash is a pricey machine. The 9.9 XO1 I tested rings in at $7,999 (ouch), and that’s not even the highest tier model—if you’ve got $10k to burn and want the best of the best, check out the 9.9 XTR, which features Shimano XTR brakes and drivetrain. We think the XO1 is still a better deal, because while Shimano’s XTR package is certainly superior, it’s not $2,000 superior, and it’s actually slightly heavier than the XO1. Obligatory sticker shock complaints aside, there are plenty of high-end enduro bikes that ring in at a similar price point to the XO1, without the high-end components—$7,999 is a huge chunk of change, but at least the components reflect that.

The Slash 9.9 build kit leaves absolutely nothing to be desired. | Max Ritter photo.

The aluminum options are significantly less expensive, and the Slash 8 ($4,199) is probably the best value since you’ve still got a fancy RockShox suspension package as the higher end models just without the carbon frame. The 7 is the lowest tier option, but it only costs $500 less than the 8, and has significantly more basic components.

Money talk aside, I credit a huge part of my progression over the last year to this bike. A lot of people say “It’s not the bike it’s the rider,” but choosing a bike that’s built to chew up terrain like the Slash is a no-brainer if you’re looking to push your own limits. I’m not saying this should be anyone’s first mountain bike, but you don’t have to have your sights set on the podium to enjoy flying downhill on the Slash. I loved the Slash so much I convinced my 57-year-old mom to buy one (yes, she hucks to flat), so if you’re not a bro rocking a Fasthouse kit, don’t think this bike isn’t for you. 

Get one at your local Trek Dealer, or check out options at Custom paint and builds are available through Trek's Project One.

From The Column: TGR Tested

About The Author

stash member Lily Krass