Trek shook up their mountain bike lineup for 2017, and when the dust had settled from those revisions it was the Slash that ended up on top as the most purebred, race-oriented bike of the bunch, designed for the rigors of the Enduro World Series circuit. Built around 29” wheel and with a full carbon frame that Trek claims is as stiff as their Session DH bike, the new Slash has 150mm of rear travel paired with a 160mm fork up front.
There are two complete versions of the Slash, the 9.9 Race Shop Limited reviewed here, which retails for a bank account emptying $8,000 USD, and the 9.8, which comes in at $5,500. There's also a frame-only option for $3,700, a price that includes a Fox Float X2 shock.
Trek's Knock Block keeps the fork's crown from contacting the frame.
There are two geometry settings, but the writing on the frame can be a little confusing - the low position (shown) is with the bolt in the most rearward position.
This is one of the few times where the well-worn phrase, “Looks like a Session,” is acceptable, because yes, the Slash does bear more than a passing resemblance to its downhill-oriented sibling. The frame is constructed from Trek's OCLV carbon fiber, and has an oversized, squared-off downtube, part of Trek's new 'Straight Shot' design, which is also found on the Fuel EX and Remedy models.
The frame's downtube shape means that the fork's crown will hit the frame if it's turned too far, but that's where the Knock Block system comes in. A replaceable stop chip located on the top tube works with a keyed headset top cap in order to limit the fork's turning radius, while a keyed stem and spacers ensure everything remains lined up. Non-Bontrager stems are compatible with the Knock Block system, although you'll need to purchase a special clamping headset spacer in order to run one. There's also a rubber downtube protector for one extra level of frame protection.
It used to be that achieving adequate tire clearance on longer travel 29ers was a tricky proposition, but thanks to the advent of 1x drivetrains and 12x148mm rear spacing that's no longer as much of an issue. On the Slash the amount of clearance is especially generous, with enough room to fit a 29 x 2.6” tire, a width that's still somewhat of a rarity, although I wouldn't be surprised to see some wider rubber hit the market in the near future.
The Slash uses a BB92 bottom bracket, and while I would have preferred a threaded bottom bracket, out of all the pressfit standards I've had the best luck with BB92. Internal routing is in place for derailleur, brake, and dropper post housing using Trek's Control Freak cable management system, which involves threading a zip tie through a port in the down tube to hold everything in place. It's not as quite as easy of a system to work with compared to frames full length guide tubes molded into them, and a couple of bent spokes and some patience are sometimes necessary to get everything cinched down.
Other details include ISCG 05 tabs for mounting a chain guide, and, thankfully, a spot to mount a full-size water bottle on the top of the downtube.
The Slash uses Trek's Active Braking Pivot (ABP) suspension design, where the rear pivots are positioned around the rear axle, but there's one notable difference compared to the layout found on the Fuel EX, Remedy, and even the Session – the shock is mounted directly to the frame, rather than 'floating' between the chainstays and upper rocker link. According to Trek, this change gave them more room to work with in the lower frame area, and made it possible to fit a longer piggyback shock, in this case a metric Fox Float X2 that measures 230x57.5mm.
In the low setting the Slash is one of the slackest 29ers currently on the market, with a 65.1-degree head angle. There are slacker big wheelers in existence – the Pole Evolink and Nicolai Geometron come to mind – but not many. For comparison, the Specialized Enduro 29 has a 66-degree head angle, the Evil Wreckoning's is 65.5-degrees, and Nukeproof's Mega 290 sits at 66-degrees.
Fox Factory Float X2, 2-position damper, 230x57.5mm
Fox Factory 36 Talas, 130/160mm travel
FSA Knock Block IS-2, E2, sealed alloy cartridge
SRAM XG-1295, 10-50, 12 speed
SRAM X01 Eagle, 32T Direct Mount X-Sync
SRAM X01 Eagle
SRAM X01 Eagle, 12 speed
Bontrager Line Pro, OCLV Carbon, 35mm, 27.5mm rise, 780mm width
Getting the Fox Float X2 shock set to my liking took more tinkering than I'm used to, and for the first few weeks I played with a number of air pressure, compression, rebound, and volume spacer configurations. The Slash has a progressive suspension curve, but the amount of ramp up at the end of the travel isn't as dramatic as on a bike like the Nukeproof Mega 290, or the YT Jeffsy, which means more aggressive riders may need to add an additional volume band.
I ended up doing just that, installing one more volume band to the X2 in order to add more end stroke ramp up, which brought the total up to five, the maximum allowed given the shock's dimensions. My final settings ended up being 180psi for 17mm of sag, low-speed compression all the way open, 19 clicks out on high-speed compression, 20 clicks out on low-speed rebound, and 7 clicks out on high-speed rebound.
A good amount of my time aboard the Slash was spent grinding up logging roads in order to access the type of steep, technical terrain this red machine was built for. With the rear shock set fully open there is a fair bit of suspension movement, especially during out-of-the-saddle pedaling, but luckily all it took was a flip of the blue, two-position lever on the Float X2 and I could comfortably spin away as long as necessary to reach the goods.
Along with taking full advantage of the Float's compression lever, I regularly made use of the Eagle 12-speed drivetrain's largest, 50-tooth cog, especially when the ground was soggy and saturated, and forward progress slowed down to a crawl. Where I live, that extra range makes a lot of sense, and makes it easy to conserve energy for the fun parts of a ride.
It was on more technical climbs that the Slash's downhill proclivities begin to show, and while I wouldn't say it ever felt unwieldy, the slack head angle does give it a more subdued demeanor; a little more attention is required to keep the front end on track. Of course, it is possible to drop the Fox 36's travel down to 130mm on the fly, which should theoretically improve the climbing performance, but I simply didn't find that to be the case. My weight balance felt better on the climbs and descents with the fork set to its full 160mm of travel.
There's also the Slash's adjustable geometry to consider. I ended up settling on the low geometry setting, but I'm lucky enough to live in an area that's rife with DH-style trails. The difference between the positions isn't drastic, but it its noticeable - I could certainly see using the high setting in areas with more rolling, less steep terrain in order to speed up the bike's handling.
Compared to its contemporaries, I'd place the Slash's climbing manners somewhere in between the steady-rolling Nukeproof Mega 290 and the livelier Yeti SB5.5. It's not likely that you'll suddenly find yourself smashing hill climb PRs, but considering its intended purpose – crushing the gnarliest tracks on the EWS circuit – it's hard to fault the Slash's uphill performance.
The Slash feels exactly like a race bike should – it's stiff, responsive, and extremely stable. Now, stiffness is one of those traits that can be hard to quantify, especially when there's six inches of suspension between you and the ground, but there's a satisfying precision to the Slash's handling. Feel like taking that cheeky inside line, the one with the nearly ninety-degree exit? Or would you rather go wide, blazing a round, clean arc on the very edge of the trail? In either case, the Slash is an unflinching machine, no matter how hard it's pushed.
The rear suspension doesn't feel quite as plush as the current version of the Specialized Enduro (which makes sense, considering the fact that there's a 15mm travel difference between the two bikes), but after I'd found the sweet spot with the Float X2 I was able to cruise right through chunky sections of trail at full speed without getting hung up or knocked off line. There's plenty of traction on hand, thanks to the combination of the larger wheels and a sensitive shock, which helps keeps the rubber on the ground even in loose or slippery conditions. I did reach the end of the travel a little more often than I would have liked, even with the maximum amount of volume spacers in place. This may have more to do with the X2 shock than the bike's suspension curve, but in any case I wouldn't have minded a little more bottom-out resistance.
The Slash feels exactly like a race bike should - it's stiff, responsive, and incredibly stable.
When it comes to bike geometry, how slack is too slack? I don't think we've reached the limit yet, at least when it comes to all-mountain / enduro race bikes, and the Slash helps to illustrate that point. As long as the trail was pointed downhill, the 65-degree head angle didn't feel floppy or sluggish, even at slower speeds. Chainstay length plays a role in this equation as well, and at 434mm the Slash's back end is short enough that cranking it around tight turns didn't pose a problem. That being said, the Slash does reward an aggressive rider, one who isn't afraid to push the front wheel into turns and to really lean into the bike in order to make the most of its angles.
Compared to the Yeti SB5.5 the Slash feels a little more glued to the ground – it would rather plow than pop over smaller obstacles. Put the lip of a lofty jump in front of it, though, and the it'll soar skyward with ease. I even took it down some proper 'freeride' trails, full of nicely-sculpted jumps that were originally built with smaller-wheeled bikes in mind, and the Slash handled it all. In the air, it feels closer to a DH bike than a trail bike, with a calm stability that makes it easy to get lined up and ready to return to earth.
I usually try to avoid using the phrase 'confidence inspiring' in bike reviews, due to the fact that it's in danger of becoming a tired cliche used to describe everything from helmets to socks, but I'm going to make an exception in this case. Those two words are a fitting description for the Slash's performance in steep, rough terrain, and whether I was riding down loose, rutted chutes that snaked straight down the fall line, or moss-covered slabs of near vertical rock that require accurate braking and full commitment, I was consistently floored by how solid and composed the Slash felt. It's one of those bikes that makes you think, "I've got this," time after time, no matter how treacherous the trail ahead appears.
There are a lot of Bontrager-branded components on the Slash 9.9, but the vast majority are well designed and constructed.
With a 780mm carbon bar and a 40mm stem, there wasn't any need to make changes to the bike's cockpit.
• Bontrager bits: Considering the RSL's price, there sure are a lot of house-brand parts on this bike. Bontrager does make some very nice parts – the carbon bars and SE4 tires are all excellent components - but I could see some riders balking at the lack of flashy bits from companies with more aftermarket cachet.
• Fox TALAS 36: The Fox TALAS 36 remained buttery smooth for the duration of testing, although I would have preferred to see the regular Float version spec'd instead of the Talas. Aside from the fact that I never felt the need to lower the front end for climbing, there's no way to add or subtract volume spacers from the fork to increase or decrease how progressive the fork is. That's something I'd imagine many riders would want to do, especially the racer types that this bike is aimed at.
• Bontrager Drop Line Post: Trek says that the Slash is spec'd with a 125mm dropper in order to allow it to fit a wider range of riders, but I'm not convinced that reasoning is sound. Given the terrain this bike is designed for, it only makes sense that most riders would want their seat as far out of the way as possible; at the very least the 19.5 and 21.5 frames should have 150mm posts. At 5'11” I was able to swap out the Drop Line for a 150mm Fox Transfer post with plenty of room to spare on the size large.
• Bontrager Line Elite Wheels: The Line Elites held up well, and they're still true even after a few months of being banged against roots and rocks. Setting tires up tubeless was a breeze, and the 28mm internal width plays with wider tires, making it possible to run lower pressures without needing to worry about the tire peeling off in the middle of a hard turn.
It's easy to get sucked in by the Slash's good looks and DH-inspired geometry, but don't forget to be realistic about the terrain you regularly frequent. This is a bike with a healthy need for speed, one that thrives when the going gets steep and rough. If you have the terrain and the confidence to fully take advantage of the Slash's potential, it's a potent weapon out on the trail, and one of the best descending longer travel 29ers currently on the market. - Mike Kazimer
About the Reviewer Stats: Age: 34 • Height: 5'11” • Inseam: 33" • Weight: 160lb • Industry affiliations / sponsors: None Twenty-two years deep into a mountain biking addiction that began as a way to escape the suburban sprawl of Connecticut, Mike Kazimer is most at home deep the woods, carving his way down steep, technical trails. The decade he spent as a bike mechanic helped create a solid technical background to draw from when reviewing products, and his current location in the Pacific Northwest allows for easy access to the wettest, muddiest conditions imaginable.