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2021 Trek Slash 9.9 X01 Bike

Vital Rating: (Outstanding)
2021 Trek Slash 9.9 X01 (Lithium Grey)
2021 Trek Slash 9.9 X01 Bike 2021 Trek Slash 9.9 X01 Bike 2021 Trek Slash 9.9 X01 Bike 2021 Trek Slash 9.9 X01 Bike 2021 Trek Slash 9.9 X01 Bike 2021 Trek Slash 9.9 X01 Bike 2021 Trek Slash 9.9 X01 Bike 2021 Trek Slash 9.9 X01 Bike 2021 Trek Slash 9.9 X01 Bike 2021 Trek Slash 9.9 X01 Bike 2021 Trek Slash 9.9 X01 Bike 2021 Trek Slash 9.9 X01 Bike 2021 Trek Slash 9.9 X01 Bike 2021 Trek Slash 9.9 X01 Bike
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We Ride the Not-So-Secret 2021 Trek Slash (and love it)

We're having to re-think what it means to ride a long-travel 29er thanks to the new Slash.

Rating: Vital Review
We Ride the Not-So-Secret 2021 Trek Slash (and love it)


Look here Trek Slash, it's not me, it's you. I just don't have a place in my life for a 160/170mm-travel 29er. Who does? A 469mm reach on an M/L size? That's a bit much for my 5'9" frame, and how is that really a size? Wait, you're saying there's more to you than reach and travel numbers? Ok, I'll listen. After all, a mind is like a parachute. Steeper seat angle, slacker head angle, integrated tools, and storage, I like all these features. Do go on...


  • From rough to buff, it masters all trails
  • Comfortable pedaling position
  • RockShox ZEB is butter-smooth
  • Endless confidence in the corners
  • Easily popped off features and jumps
  • Super Deluxe has meaningful adjustments
  • Plenty of frame protection that can be removed


  • Stock gearing is too low
  • GX cassette on an X01 build
  • BITS tool in stem was finicky
  • Cracked rim


  • OCLV Carbon frame (alloy options available)
  • 29-inch wheels only
  • 160mm (6.2-inches) of rear wheel travel // 170mm (6.7-inches) fork travel
  • ABP suspension design
  • Removable Knock Block provides 72-degrees of turning in either direction
  • Internal cable routing
  • Proprietary RockShox Super Deluxe - 3-position compression
  • Integrated tool storage in head tube
  • In-frame storage system
  • 34.9 Seat tube
  • BSA 73mm threaded bottom bracket with ISCG mounts
  • Boost 148 rear spacing with 12mm through axle
  • Measured weight (size M/L, no pedals): 32 pounds 5 ounces (14.65 kg)
  • MSRP $7,999 USD


The all-new Trek Slash has been leaked on the Vital forums for some time and received a few lackluster replies from our community. The Meh-sayer crowd may want to take a second look. Our first glance at the Slash's stats had Vital testers feeling like this big-rig may need a spinner knob on the handlebars to handle switchbacks and only the biggest of descents would be worth riding. After all, isn't under-biking all the craze these days? With so many good bikes out there that can do so much, what's the point of the Trek Slash outside the EWS tape? This is where things took a hard left turn, the new Slash isn't a good bike. It's a great bike.



The new Trek slash access all of the current trends in an aggressive design and even pushes things with five size offerings. Within the standard Small to Large range is an ML size for riders on the cusp of the medium and large or those who just want a longer bike. With the Slash being ridden by multiple testers, this is where we landed. By the numbers, here's the breakdown of our M/L Slash: seat angle: 75.6, head angle: 64.1, reach: 469mm, chainstay: 435mm, seat tube length: 435mm. A 35mm stem and 150mm Bontrager dropper rounded out the fit department. As suspected, in every respect, the Trek goes longer, lower, and slacker where it matters.

Seat Angle Update

On paper, the Slash's seat angle is not on par with other enduro bikes today. In practice, we did not notice the seat angle or even feel hindered by it. On perhaps only the most questionably steep portions of the trail, did we feel the need to get over the front of the seat to keep the front end in check. Riders with longer legs may find themselves sliding the seat forward on the rails to push their weight forward.

APPROXIMATE actual seat tube angle values with 150mm Bontrager Line Dropper at different insertion depths

Slammed seat post yields 77.4-degree actual seat angle
Mid-height seat post yields 76.6-degree actual seat angle. (These measurements are approximate for visual reference only).
High seat post yields 75.7-degree actual seat angle

Custom RockShox Super Deluxe shock with 3-position damping and lockout.


In testing the latest Remedy and Rail, Vital testers have had a tumultuous relationship with the ReActive Thrushaft system spec'd. Quite honestly, in both cases, a production shock would have been preferred. The Slash does still have a Thrushaft but gone is the ReActive valving and the curiously small piggyback is now full-sized. The shock itself is still custom and exclusive to the Slash, featuring a numeric compression adjustment and relocated climb switch.

The compression adjuster has three settings: +, 0, and -. The + setting increases damping and is designed for smoother trails. The - setting is for steeper, rougher terrain while the 0 setting is a more neutral compression setting. We set the dial for 0 with 30% sag.

The numeric rebound adjuster is handy.

Only slightly less-leaked than the Slash was the RockShox ZEB, which graces this bike with its muscly presence. Setup was just under 70-pounds for our 170-pound testers. High-speed compression was wide open with 6-clicks of low speed.

A quick trim of the bars and we were off to the trails!

What was the worse-kept secret? The RockShox Zeb or the Trek Slash?

On The Trail

The Slash was shuttled to Trail 4, the same rowdy descent used in our e-bike tests, for a proper flogging. Next was the bike park for laps on laps. In both scenarios, both testers immediately loved the Slash. For such a large bike, it was fast on its feet and eager to maneuver and pop down the trail. Throwing the Slash into corners is great fun, just lean harder and it seemingly never loses composure. Smaller tables and jumps are easily popped with much better feedback than any bike this size should deliver.

From rock gardens... slopestyle lines.
It was a literal laugh-out-loud, utterly delightful ride, the Slash was that impressive

Cool story, but what about in the real world? For many riders, a number of our rides are on average to slightly mundane trails. Do you really want to haul a pig up the hill and force it to carry speed back down? This is where the Slash made its greatest impression on us. We took the Slash on a local 13-mile ride that actually grew to 15-miles with all the exploring we were suddenly keen to do.

Trek has created a big bike that cruises uphill. Using the climb switch makes the rear end much stiffer and will probably be reserved for fire roads only. On all but the steepest pitches, the front end minds its manners. In comparing GPS data from the same ride a week prior, we were faster uphill on the Slash than on a smaller travel 29er. The data don't lie.


The chief complaint with riding the Trek on trails is actually in the gearing. Someone spec'd this bike with a 30-tooth chainring mated to a 52-tooth Eagle cassette. This range is indefensibly low and by all practical measures, useless. We sincerely tried but at no point on any climb could we manage to make use of this gear. Riders will need a spastic cadence to keep the bike going fast enough, just to maintain balance uphill. When riding by feel, not trying to purposely access the larger cogs, we never came close to needing or using the easier spectrum of gears, they stayed unused. Outside of the 52-tooth, on flat portions or descents, our testers were slapping through gears far too quickly and running out of gears. This combination, essentially, makes an 11-speed of the Slash's drivetrain. Riders should install at least a 32-tooth before leaving the bike shop.


During the trip back to the truck, the Trek seemed to have an auto-adjusting, morphing quality to it. Nuke as fast as you can into that corner and lay it down, traction and composure until the sun goes down. Small bump over there, pop, and fly. Roots and nastiness, nom-nom-nom, Slash eat it up. It was a literal laugh-out-loud, utterly delightful ride, the Slash was that impressive. In subsequent weeks, four different testers all fell in love with the Slash, concurring on all of the trail behaviors and antsy to ride it.

Build Kit

We love the downtube storage on the Trek Slash, it's easy to use and the side-load cage is awesome. The storage compartment includes a slender bag to make accessing your items a little easier.



Introduced not long ago, the Bontrager Integrated Tool System (BITS) was not without its foibles on our bike. After the first day of testing, the headset, which is held together with the BITS, jarred itself loose. After tightening it, the system stayed tight for the remainder of testing. Accessing the tools was a mixed bag. Sometimes the tool was easily pulled out, other times it was a brutal grunt-fest. To top it off, the multi-tool's assembly came loose, causing the wrenches to rattle while inside the headtube. We had to tighten the bolts that hold the tool together after only a couple of uses. We love integrated tool systems but our first impression had us a BIT...let down.

Suspension Performance

The RockShox Zeb is everything they say it is. It's buttery smooth and makes bumps disappear. We particularly appreciated the Zeb's ability to track and hold a line through rough corners, we've never had it so good.


We were very apprehensive about Trek's proprietary Super Deluxe but after all of our riding, apprehension has given way to acceptance. The compression tuning options are noticeable and improve the Slash's ride qualities for the given terrain. Putting the shock in the + position (with two more clicks of low-speed in the fork) for flow trails resulted in a bike that wanted to boost lips all day, it was a total gas. We took the Slash for two back-to-back runs on the same rough trail. The first run had the shock in the 0 position, the second with the shock in the - position. Our second run delivered improved wheel tracking and less dancing on the pedals. The collaboration with RockShox and Trek has definitely paid off. Time will tell how the system holds up for the long-term but there were no immediate indicators of forthcoming issues.

For those wondering, many aftermarket shocks will fit, including:

  • MY21 Fox X2 Coil
  • MY21 Fox X2 Air
  • RockShox Super Deluxe Coil
  • Fox DPX2
  • MRP Hazard
  • Most inline shocks (no reservoir/piggyback)

The standard RockShox Super Deluxe air shock does not fit due to lockout lever interference in the last 1/3 of the travel. The new Super Deluxe Thru Shaft uses a new shock body from RockShox that provides more clearance.



Our Slash 9.9 X01 retails for $7,999. For that price, we have to call out the GX cassette. Certainly, every part on this bike is top-shelf but so is every part on most any bike at this price, including the cassette.

GX cassette that's stock on the slash. Some shots in our video have an X01 cassette that was on the Bontrager wheel we took off a Trek Rail used to complete our test.

Other than a broken chain from some uphill "power-shifting", the SRAM Eagle drivetrain worked like it typically does, which is great.


Our Slash came with a Bontrager SE5 2.6-inch front and SE4 2.4-inch in the rear. This combo works fantastic when laying the bike deep on its side. On more than one occasion, we tried to be cool-guys and drift the bike only to simply rail the corner. The Slash can slap but it prefers pulling G's through the apex.

2.6 Bontrager SE5 up front
2.4 Bontrager SE4 out back

Wheel Performance

Bontrager's Line 30 carbon wheels are stiff and roll amazingly fast. On the Remedy and Rail, we subjected the Line 30 to copious amounts of abuse. The Line 30 on our Slash did not fare as well, suffering a crack that had it no longer holding air. We're going to call this one the outlier but it deserves being called out. We contacted Trek for clarification on the warranty offered. Here was their feedback:


"Every set of Bontrager carbon wheels is backed by the Carbon Care Wheel Loyalty Program, which provides free repair or replacement in the unlikely event you damage your wheels within the first two years of ownership (and deeply discounted rebuild or replacement to the original owner regardless of the date of purchase after those first two years). Additionally, we back every carbon Bontrager wheelset with a lifetime warranty to the original owner."

"Full details on the warranty can be found HERE.

Long Term Durability

Our Slash hit a rock or 20 during its time with us, suffering only a couple of small scratches. The frame protection Trek has installed is robust and the paint quality is solid. Aside from our broken chain and rim, there was nothing about the Slash that threw a red flag on the durability front.

At the end of the test, the Slash had us reassessing what a long-travel 29er should be.


What's The Bottom Line?

Alright, Trek Slash, where does this leave us? You aren't perfect but your flaws are fleeting and easily remedied. When it comes down to what matters, the bones that make you what you are, therein lies the magic. The details are sound, the climbs easily tackled and at the bottom of the hill it is all smiles. At the end of the test, the Slash had us reassessing what a long-travel 29er should be. As we said, the Trek Slash isn't a good bike, it's a great bike.

Visit for more details.

Vital MTB Rating

  • Climbing: 4 stars - Excellent
  • Descending: 5 stars - Spectacular
  • Fun Factor: 5 stars - Spectacular
  • Value: 3 stars - Good
  • Overall Impression: 4.5 stars - Outstanding

About the Tester

Brad Howell - Age: 41 // Years Riding: 26 // Height: 5'9" (1.75m) // Weight: 170-pounds (77.1kg)

Brad started mountain biking when a 2.25-inch tire was large, and despite having threads, bottom brackets sucked. Riding in the woods with friends eventually lead way to racing, trying to send it at the local gravel pits, and working in bike shops as a wrench to fix those bikes. Fortunate enough to have dug at six Rampages and become friends with some of the sport’s biggest talents, Brad has a broad perspective of what bikes can do and what it means to be a good rider. For several years Brad worked in the bike industry and got to see the man behind the curtain. These days, though, he just likes riding his bike in the woods with friends.

Video and Photos by gordo


Product Trek Slash 9.9 X01 Bike
Model Year 2021
Riding Type Enduro / All-Mountain, Freeride / Bike Park
Rider Unisex
Sizes and Geometry
S (High, Low), M (High, Low), ML (High, Low), L (High, Low), XL (High, Low) View Geometry
Size S (High, Low) M (High, Low) ML (High, Low) L (High, Low) XL (High, Low)
Top Tube Length 584mm, 585mm 609mm, 610mm 628mm, 629mm 647mm, 649mm 683mm, 684mm
Head Tube Angle 64.6°, 64.1° 64.6°, 64.1° 64.6°, 64.1° 64.6°, 64.1° 64.6°, 64.1°
Head Tube Length 100mm 100mm 105mm 115mm 140mm
Seat Tube Angle 76.1°, 75.6° 76.1°, 75.6° 76.1°, 75.6° 76.1°, 75.6° 76.1°, 75.6°
Seat Tube Length 395mm 420mm 435mm 450mm 500mm
Bottom Bracket Height 352mm, 345mm 352mm, 345mm 352mm, 345mm 352mm, 345mm 352mm, 345mm
Chainstay Length 435mm, 437mm 435mm, 437mm 435mm, 437mm 435mm, 437mm 435mm, 437mm
Wheelbase 1197mm, 1197mm 1212mm, 1222mm 1242mm, 1243mm 1263mm, 1264mm 1304mm, 1305mm
Standover 711mm, 705mm 749mm, 743mm 749mm, 743mm 759mm, 753mm 779mm, 773mm
Reach 431mm, 425mm 456mm, 450mm 744mm, 469mm 491mm, 486mm 521mm, 516mm
Stack 618mm, 621mm 618mm, 622mm 622mm, 626mm 631mm, 635mm 654mm, 658mm
* Additional Info Bottom bracket drop: 22mm, 29mm
Trail: 130mm, 134mm
Multiple values represent geometry with Mino Link in High and Low positions, respectively
Wheel Size 29"
Frame Material Carbon Fiber
Frame Material Details OCLV Mountain Carbon main frame and stays with Carbon Armor chainstay guard and dual-density full-length downtube guard, magnesium rocker link
Rear Travel 160mm
Rear Shock Custom RockShox Super Deluxe Ultimate, DebonAir spring, Thru Shaft 3-position damper, improved standard shim damper, numeric rebound, oversized thermal compensator, tunable open setting, 230x62.5mm
Fork RockShox ZEB Ultimate, DebonAir spring, Charger 2.1 RC2 damper, tapered steerer, 44mm offset, Boost 110, 15mm Maxle Stealth
Fork Travel 170mm
Head Tube Diameter Tapered
Headset Knock Block 2.0 Integrated, 72° radius, cartridge bearing, 1-1/8" top, 1.5" bottom
Handlebar Bontrager Line Pro, OCLV Carbon, 35mm diameter, 27.5mm rise, 820mm width
Stem Bontrager Line Pro, 35mm length, Knock Block, Blendr compatible, 0° rise
Grips Bontrager XR Trail Pro, alloy lock-on
Brakes SRAM Code RSC 4-piston hydraulic disc, 180mm/200mm SRAM CenterLine, 6-bolt, round-edge rotors
Brake Levers SRAM Code RSC
Drivetrain 1x
Shifters SRAM X01 Eagle, 12-speed
Front Derailleur None – 1x only
Rear Derailleur SRAM X01 Eagle, 12-speed
Chainguide None included
Cranks SRAM X01 Eagle Carbon, DUB, length: 170mm (S), 175mm (M-XL)
Chainrings 30 tooth alloy, Boost (55mm chainline)
Bottom Bracket SRAM DUB, 73mm, BSA threaded
Pedals None included
Chain SRAM GX Eagle, 12-speed
Cassette SRAM XG-1275 Eagle, 10-52 tooth, 12-speed
Rims Bontrager Line Elite 30 wheelset – OCLV Mountain Carbon, tubeless ready
Hubs Bontrager Line Elite 30 wheelset – Rapid Drive 108, 6-bolt, Shimano MicroSpline freehub, Boost 148 rear, Boost 110 front
Spokes Bontrager Line Elite 30 wheelset
Tires Bontrager SE5 29"x2.60" front, SE4 29x2.40" rear, Team Issue, tubeless ready, Core Strength sidewalls, aramid bead, 60 TPI
Saddle Bontrager Arvada, austenite rails, 138mm width
Seatpost Bontrager Line Elite Dropper, internal routing, travel: 100mm (S), 150mm (M, M/L), 170mm (L), 200mm (XL)
Seatpost Diameter 34.9mm
Seatpost Clamp Standard single bolt
Rear Dropout / Hub Dimensions Boost 12mm x 148mm
Max. Tire Size 29"x2.50"
Bottle Cage Mounts Yes – one inside front triangle plus integrated storage in downtube
Colors Lithium Grey, Factory Orange/Carbon Smoke, or Carbon Blue Smoke
Warranty Lifetime for main frame and swing arms to the original owner
Weight 31 lb 2.2 oz (14,125 g)
Miscellaneous Internal storage in downtube with Bontrager BITS Internal Frame Storage Bag
Mino Link adjustable with High and Low positions
Knock Block 2.0 with increased turning radius from 58° to 72°
Control Freak internal routing
Shuttle friendly dual-density full-length downtube guard
Downtube clearance for fork crown
New suspension layout from the previous generation
Project One customizable
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