First ride review of 2021 Trek Slash 9.9. Trek’s 29in enduro trail blazer returns with more travel and a progressive makeover.

>>> Best enduro mountain bikes: 150 to 170mm travel full suspension bikes

Trek Slash 9.9 need to know

• Trek ups the travel on the Slash 29 by 10mm – it 
now gets a 170mm-travel suspension fork with 160mm out back
• The sizing and geometry both move forward, making the frame longer and slacker than before
• Storage has been added to the down tube, and it isn’t exclusive to the carbon models
• Carbon frame with magnesium rocker link and a 34.9mm seat tube diameter for increased dropper post insertion
• New Knock Block design increases the steering angle from 58º to 72º
• Trek offers a five-model range, starting at £2,650 for the alloy Slash 7

The new Slash offers a razor-sharp ride and point and shoot thrills

Back in 2016, when Trek first launched the Slash 29, you could count the number of long-travel big wheelers on 
one hand. Fast forward to today, and the race to be first at any EWS is consistently contested by the likes of Sam Hill and Richie Rude, both riding 29ers. So 29in wheels dominate racing at the highest level, but what has Trek done to guarantee that the latest Slash 29 is every bit as cutting edge as the original? What it hasn’t done is burn the house to the ground and start over. At first glance, the new bike looks a lot like the old one, but even after one ride, it’s clear that it’s a very different proposition. Yes, the OCLV Mountain carbon frame casts a similar shadow, but everything about this bike is different, from the sizing to the travel; even the Knock Block headset has been updated.

ABP suspension design with tweaked kinematics uses custom Thrushaft shock

Let’s start with travel. The old Slash 29 was a 150mm bike with a 160mm fork. The new version gets 10mm more travel at both ends. I measured vertical rear-wheel travel at 157mm so it can definitely be classed as a 160mm bike. The geometry is not quite as accurate though, as I measured the head angle on the new Slash at 63° in the low setting. That’s one-degree slacker than claimed. Not that I’m complaining, because the steering response feels neutral, and at no point did the bike feel too slack. In fact, I was taken aback when I measured the geometry for the first time and discovered that it was much slacker than it felt. The reach on the size large measured a generous, but not overly long, 475mm, but to get a better picture of the sizing we need to take a closer look at the wheelbase. With 1,273mm spanning the contact patches, the new Slash delivers a footprint that’s every bit as big and as stable as the S4 Specialized Enduro.

Down tube storage compartment specced throughout the range

Trek’s signature ABP suspension has also been tweaked. The progression rate and anti-squat have both increased and the Slash now gets a custom Thrushaft RockShox SuperDeluxe shock, with a choice of three compression settings in the open position and an easy-to-reach lockout. The idea being that you can tune the amount of low-speed support you need to match the terrain. In reality, the difference between the three settings is subtle, so I think most riders will leave it in the middle position and be done with it. In playing with the compression settings I did discover that the bypass for the lockout is really effective though, and you can still ride hard even if, like me, you sometimes forget to open up the shock for the descents.

Knock Block steering range has increased to 72°

One pet peeve with the old Slash was the slack 64.6° seat tube angle. Climb anything remotely steep and your weight ended up too rearward, loading the suspension and resulting in increased pedal strikes. To address this, Trek has steepened up the actual seat angle by one degree (actual measured geometry from both bikes). It doesn’t sound like a big change, but it is enough to give an effective seat angle of 75.5°, more than steep enough to winch up anything that I wouldn’t consider getting off to push up. Trek has also boosted the climbing prowess of the Slash by reworking the chainstay to accommodate a smaller 28t chainring. The bike ships stock with a 30t ring, and if you’re looking for more top-end speed, the biggest chainring the frame will accommodate is a 34t. With the expanded 10-52t range of the latest Eagle cassette however, I can’t see many riders needing a 28t ring on the Slash 9.9 X01. Still, it’s good to have it in your back pocket for big days in big mountains if the chairlift isn’t running.

10-52t Eagle cassette offers wide spread of gears

Other tweaks to the latest Slash see Trek dispense with the Straight Shot down tube and increase the range of the Knock Block steering lock from 58° to 72°, so you can now turn on a dime. The updated frame layout also gives you the option to remove the Knock Block entirely, but if you’re racing I still think it’s a worthwhile safety mechanism, as it should stop cables getting ripped out in a crash.

160mm-travel RockShox SuperDeluxe shock with three compression settings

One of my favourite updates to the Trek Slash 9.9 is the addition of down tube storage, first introduced on the Trek Fuel EX. Best of all, it’s also on the aluminium models further down the Slash range. In an interesting move, Trek has shunned the tube-within-tube design for its internal cable routing, the door in the down tube making it pretty easy to run the cables though the frame and out to the stays. I’m not sure it’s a good move though, as there’s quite a bit of cable rattle. Stuffing an inner tube and some snacks into the down tube quietened it down a bit, but all of the cables on our test bike were really long, and constantly rattled against each other. Fingers crossed, shortening the cables will be enough to improve the acoustics on this otherwise silent ride.

How it rides

I’m always suspicious of any enduro bike that pedals as well as the new Trek Slash 9.9. Sure, they tend to feel amazing when pootling along on your local trails, then you take it somewhere fast, rough and demanding, only to discover the shortcomings in the suspension within the first few turns. Thankfully, the new Trek Slash isn’t one such bike.

Yes, you can still be as precise as a fine-tipped pen when you need to be on a specific line, but the Trek Slash 9.9 also allows you to paint in broad brush strokes, so you can ride with reckless abandon and let your creative juices flow on any canvas. It’s what makes the Slash such an easy bike to ride, and to ride fast. It also makes it very versatile. While bikes like the Specialized Enduro Elite feel a lot like downhill rigs, the Slash is more manageable and maneuverable, without forcing you to tip-toe down the toughest trails. Both bikes share similar geometry, but Trek’s shorter reach actually gives you more wiggle room, not less. And if that sounds counterintuitive, it is. I think it’s because really long front ends tend to pull you into a more fixed riding position, but with the 475mm reach on the size large Slash you can move your weight around more freely simply by bending or extending your arms. This also makes it easier to load the front tyre on flatter trails. Yes, it’s about choosing your battles, so what the Trek loses in raw, straight-line speed it more than makes up for in agility, while still managing to advance the new Slash 29 on all other fronts.

Could the BB height on the Slash 29 be a hair lower? Sure it could, as I never so much as kissed a pedal on the ground, even with 175mm crankarms and the MinoLink in the low geometry setting. Did it slow the Slash 29 down any? Not one jot.