Home > Blog > New Trek Slash: one of the most advanced Enduro machines of the 2021 rig

10 Sep 2020Jacopo Vigna

New Trek Slash: one of the most advanced Enduro machines of the 2021 rig

Trek has finally presented the 2021 Trek Slash 9.9 with more travel, updated geometry and a practical storage compartment. The Trek Slash caused quite a stir when it was launched in 2016 and played a key role in shaping the 29er enduro bike category. Hardly any bike was as popular in the scene as the 29er preceding it. Will this 2021 model be the new benchmark?

Quick Overview

The most important updates of the 2021 Trek Slash are:

  • Increased the suspension travel by 10 mm to 170 mm at the front and 160 mm at the rear;
  • Geometry has also been deeply revised: the reach is longer, the seat tube angle is almost 2° steeper and the head angle is slacker (now 64.1°). The bottom bracket was lowered by a further 6 mm, despite having more travel, bringing the BB drop to 29 mm;
  • As with the Fuel EX, the American brand have equipped the Slash with a storage compartment in the down tube of both the carbon and aluminium frames;
  • New Thru Shaft Super Deluxe shock specially made by RockShox;
  • Trek have also improved many details of the Slash putting a revised Knock Block that doesn’t limit the steering quite as much, a threaded bottom bracket and bigger frame protectors;
  • On top of that, the new Trek Slash comes with a 34.9 mm dropper post offering up to 200 mm of travel.


Like its predecessor the new Trek Slash is available as an aluminium or carbon version. The kinematics and geometry of both versions are identical. Trek is also the first company to integrate the practical storage compartment in the down tube on an aluminium frame: awesome!

The rear linkage also pivots on the rear axle as for previous models. As such, the rear suspension should remain active while braking. Trek also continue to rely on their so-called Mino-Link on the new model, allowing you to adjust the geometry by around 0.5° and the bottom bracket height by 6 mm. 

The Thru Shaft technology on the shock already proved itself on the predecessor. It creates less internal friction thanks to the continuous shaft and the lack of IFP and its seals. For the new model, Trek worked with RockShox to improve on this technology. Instead of using a specially manufactured body, it is now based on the Super Deluxe which allows you to adjust low-speed compression in three stages and thus tune the bike to suit different trails.

  • Flow trails = more compression;
  • Steep natural trails = less compression.

Another update is that the rebound clicks are now numbered, making it much easier to play with the setup. If you’d prefer using a different shock on the Slash, you can do so without any problems. Most 230 x 62.5 mm Trunnion mount shocks should fit into the rear triangle (e.g. FOX DHX2, FOX X2, RockShox Super Deluxe Coil, FOX DPX2 and MRP Hazard). According to Trek, the Slash is also compatible with coil shocks. The only shock that won’t fit is the classic Super Deluxe air shock because of the position of the lockout lever. Despite having longer travel, Trek have managed to retain the kinematics of the previous Slash, only increasing the overall progression by 2%.

At first glance, the Super Deluxe in the Trek Slash looks like any other RockShox shock. However, it doesn’t have an IFP chamber, which would usually pressurise the damping oil. Instead, the damping shaft can move through the shock, sticking out of the bottom. Due to the lower pressure in the damping system, the damper should respond more sensitively and work more actively.

Trek have reworked the details too, equipping the Slash with a threaded BSA bottom bracket, which is much easier to replace than a press-fit version.

The down tube protector has been lengthened, but it can also be split in two to save weight (is that some nerd engineer mental journey?).

The cables are routed internally and are secured in place at two positions in the storage compartment, negating the need for foam sleeves or dedicated cable channels inside the frame.

Trek have also designed the new Slash to accommodate longer dropper posts, speccing a 200 mm travel Bontrager model on the XL bike. Size L comes with a 170 mm version, while sizes ML and M are fitted with 150 mm travel posts. The smallest size S gets a 125 mm model. The travel of the dropper post can be reduced with spacers if needed.

The chainstay protector has also been revised. Although the chain runs very close to it, you don’t hear any slapping.

For the rear end, Trek continues to rely on the established 148 mm Boost standard that they introduced. To increase the clearance around the chainring, they choose to fit the latest SRAM or Shimano cranks with a 55 mm chain line.

Geometry Analysis

You can tell the age of the previous Slash by its short reach and the very slack seat tube angle. Trek have updated both of these aspects on the new model. In size L, the new bike has a reach of 486 mm, 33 mm longer than previously. The chainstays have only increased by 2 mm to 437 mm. The seat tube angle has been made 1.9° steeper, but at 75.6° it’s still pretty slack by today’s standards, especially as the effective angle slackens the further the dropper post is extended. The bottom bracket is lower than its predecessor too, but the 29 mm drop isn’t extreme. The intermediate ML size, on the other hand, is an excellent addition as it will make things much easier for all those riders who find themselves between two frame sizes. In general, we like that Trek is offering the Slash in five sizes, thus making an optimal fit available to as many riders as possible.

Overview of the various Trek Slash 2021 models

Trek are offering the new Slash in two aluminium models and three carbon versions. The 9.8 and 9.9 carbon models are further split between versions with a SRAM or a Shimano drivetrain and different colours, including a completely customised paint job thanks to Trek’s Project One concept. Pricing for the new range starts at € 2,999 for the Slash 7. However, the most attractive model for most riders will be the € 3,499 aluminium Slash 8, which leaves little to be desired in terms of its components. The most affordable carbon model is the Slash 9.7, retailing for € 4,499. Topping the range is the Slash 9.9 XTR Project One bike for € 9,099.

Both the carbon and aluminium frames are available separately for € 3,999 and € 2,499, respectively. Compared to the complete bikes, this doesn’t seem like a very sensible option for most buyers.


With a series of updates, Trek aims to put the Slash back on the podium. Thanks to its plush suspension and capable geometry, it’s ready to take on the most demanding trails. The integration of the storage compartment, the comeback of the threaded BSA BB and the longer dropper post are great. However, there’s little innovation and the unsuitable tires, the small brake rotor, the still slack seat tube angle and the lack of adjustability on the rear shock cloud the otherwise completely positive impression of this 2021 Trek Slash.


  • plush suspension
  • practical storage compartment in the down tube (also on the aluminium frame)
  • composed handling in rough terrain
  • beautiful paint job
  • additional ML frame size for the perfect fit


  • unbalanced in flat and open corners
  • minimal adjustment options on the rear shock
  • tires and small rear brake rotor don't do the bike justice

Look at the funny video they made at Trek for the Slash 2021! Find here the Trek Slash 2021 Official Promo Video

And look at this raw and real test of the Trek Slash 2021 by Vital MTB:

Source: Enduro-MTB.com, Trekbikes.com