Trek Slash 9.9 X0 AXS Mountain Bike Review


Words by Drew Rohde  |  Photos by Staff

After nearly six months of abuse, conversations with Trek Bikes HQ and a YouTube Service Bulletin video full of interesting comments, we’re kicking off the new year with a high pivot, Gen 6 Trek Slash review that should be another great conversation piece as one of the hottest bikes of 2023. We’ve been fans of many of Trek’s bikes over the last few years from the Session DH bike to their Fuel EX and Fuel EXe and of course, the last generation Slash. We first rode the Gen 6 Trek Slash during Crankworx Whistler, where we filmed a Dissected Feature with their engineer: Trek athlete Casey Brown and more. Since then, we spent the rest of summer in the bike park, pedaling backcountry trails and yes, filming a service video on the famous “Chain dropping” issue that commenters had us thinking was affecting nearly everyone who owned one of these bikes. But…as the saying goes, don’t believe everything you hear. Even if you don’t believe what we’ve got to say when it comes to the goods and bads of the new Trek Slash, we think you’ll find it entertaining at least.


• 170mm High Pivot ABP Suspension
• Mixed Wheel (29”F/27.5”R) as standard, dual 29” option
• HTA 63.3
• STA 76 (effective)
• REACH 490 (Large)

Frame: OCLV Mountain Carbon | 170mm
Fork: RockShox ZEB Ultimate 170mm | Charger 3 RC2
Shock: RockShox Vivid Ultimate 230x65mm

Brakes: SRAM Code Silver | 200F/R Centreline rotors
Bar/Stem: Bontrager RSL Integrated | OCLV Carbon | 820mm | 27.5mm Rise | 35mm Length
Headset: Integrated Sealed Bearing
Seatpost: RockShox Reverb AXS | S: 100mm, M-XL: 170mm
Saddle: Bontrager Arvada

Hubs: Bontrager Rapid Drive 108
Rims: Bontrager Line Pro Carbon
Front Tire: Bontrager SE6 Team Issue | 29″ x 2.5″
Rear Tire: Bontrager SE5 Team Issue | 27.5″ x 2.5″

Bottom Bracket: SRAM DUB Threaded
Cassette: SRAM Eagle XS-1295 | T-Type | 10-52T
Cranks: SRAM X0 Eagle | T-Type | 30T | 165mm length
Shifter: SRAM AXS POD Ultimate | 12s
Derailleur: SRAM X0 Eagle AXS | 12s


  • Downhill performance is incredible

  • Rear suspension plush yet solid

  • Fast and Confident

  • Bike Park shredder

  • Vivid Ultimate


  • 3 Dropped chains (fix appears to work)

  • Steep, chunky climbing

  • Spendy

About The Trek Slash Gen 6

Packing 170mm of travel out back, the new Trek Slash claims to be a 70/30 bike, meaning Trek designed the bike to have a 70% downhill bias with a 30% nod to climbing and uphill capabilities. Needless to say, this isn’t your run of the mill XC or all-mountain bike. It’s designed and built for riders who prioritize downhill speed, composure, and confidence on the gnarliest terrain over efficiency and climbing performance.

Since this review is likely going to get a bit long, we’ll link to our Dissected Feature which has a written interview, all the tech details and a video interview and presentation on the Gen 6 Trek Slash. If you’d like to check that out, click here.

If the CliffsNotes version works for you then we’ll gloss over a few key features:

Trek Slash 9.9 X0 AXS Mountain Bike Review


Updated for 2023, the high pivot Trek Slash Gen 6 can be run with a number of wheel size configurations and can take up to a 190mm travel fork but comes with a 170mm fork and mixed-wheel setup as standard. Riders can choose a full 29er race machine, 27.5” aggro-shredder or put a dual crown 190mm with a mullet and have a mini-Session bike park rig.

With many people loving the last generation Slash, some may have wondered why Trek opted to go to a high pivot and run two idlers? Well, with Trek’s other bikes creeping up in capability and riders wanting to go faster and bigger, it seems many brands are making their bikes bigger and burlier, and of course, more high-pivoty. Trek Slash engineer, Matt Yerke told us that even though the bike’s 70% focused on DH performance, they took time to keep it versatile and pedal-friendly, as a mountain bike should be. Did they deliver? We’ll see down below.


With bikes starting at $4,399 and going up to $11,499, our Slash 9.9 X0 AXS sits on the higher end of the spectrum at $9,399 and comes with a dialed spec. If we were spending our own money however, we’d likely be checking out the Slash 9 or Slash 9.8 XT models.

Trek Slash 9.9 X0 AXS Mountain Bike Review

Chain Drop Service Bulletin and Notes from Trek

We published this How To Video to address some of the popularized videos and comments talking about chain drop on the new Trek Slash. After publishing this video and seeing all the comments, we reached out to Trek as it had us reconsidering our official stance on the long-term review you’re about to see below. The statement below from Trek, which we are taking as truthful, made us feel better and also aligned with our notions of what we’ve observed. Trek passed our concern around their Customer and Dealer Service teams and below is a small excerpt.

“First off, Trek Bicycles and I would like to acknowledge that it is frustrating to buy a nice new bike that doesn’t work exactly like it should out of the box. Luckily however, it has been a very small number of people affected and thankfully they have been far less upset than what online commenters may have you believe.

Trek’s customer service team has actually received way more calls about internet comments talking about chain drop than actual Slash owners who are experiencing the issue. We have found that a handful of riders said the fix did not entirely solve their dropping issues. We have sent out early units of our updated idler wheel to that handful of riders, one of which is Ryan Howard, who has been spending a ton of time on his Slash. We’ve been pleased to hear that those riders are no longer having any drop issues.

These will ship to dealers at no cost for any Slash owners who want to get one.” – Ross Rushin // MTB Product Manager

Trek Slash 9.9 X0 AXS Gen 6 Mountain Bike Review


When evaluating the new Gen 6 Trek Slash 9.9 X0 AXS against the previous generation Slash and current offerings from other brands in this genre, the Slash commands attention. As with any purpose-built product, the things that make it excel can also alienate or turn off others. I’m traditionally not a huge fan of high pivot bikes, though I’ve grown to like mid-high pivot bikes for certain applications. Rocky Mountain’s Powerplay eBike and the Trek Session, which we reviewed last year, are two examples of mid-high pivot bikes that I like quite a bit.

Chances are you’ve already heard the touted claims of high pivot bikes since they’ve been so heavily marketed over the last couple of years, so we’ll save you the pitch. What is undeniable though, is that they can charge over terrain and obstacles a bit better than other designs, but only if they are tuned and designed well. We have ridden some high pivots that don’t really improve much, but suffer the downsides of a high pivot, but we’re happy to report that Trek has avoided this ill fate.

SETUP | Setting up The Trek Slash was one of the easier tasks of the year. It required almost zero tuning, customization or tinkering with to feel amazing. If you’ve read our older Trek reviews, you may recall us being a bit critical about the tune being a bit too mellow, which led to heavier or more aggressive riders needing to add maximum volume reducers or going our route, contacting Fox Shox to weasel a Trek Factory Racing tuned shock, which did wonders for the bike. This is no longer an issue as Trek seem to have finally identified that if they’re going to design an aggressive bike for aggressive riders, they need to have a shock and tune that are ready for it.

The most time-consuming part of our review bike’s set up was removing the one-piece Bontrager bar and stem combo unit and replacing it with our favorite OneUp Components Ebar and stem. This resulted in a better body position and way less hand fatigue.

Trek Slash 9.9 X0 AXS Gen 6 Mountain Bike Review

DESCENDING | Trek has done a great job of making the new Slash’s suspension absolutely devour hits of all sizes. The RockShox Vivid Ultimate rear shock only compliments the insane capability of the Slash’s rear end. It is possibly the smoothest, best feeling rear suspension I’ve felt in a while. For me, a rider who loves smashing, gapping and floating rough, chunky downhill trails, it offers a very nice platform for support and control, but gets out of the way offering a bottomless and smooth feel. I could have been tricked into thinking a coil shock was mounted out back based on the composure and smoothness.

When it comes to downhill performance, the Trek Slash may be the best descending mountain bike we rode in 2023! It absolutely shreds trails with ease and begs to go faster. Whether we were lapping blown-out end of season bike park trails or remote backcountry downhills, the Slash leads the way. In fact, we can’t think of any bikes that aren’t downhill bikes that we’d want to ride in a bike park more than the Slash. The speed this bike carries, composure over braking bumps, big and little hits as well as the way it corners make it a really impressive machine.

The downside is, the compliance combined with the weight, makes this bike a little bit tougher to jib on smaller features at slower speeds. It absolutely still gets off the ground and is fun to play on, it just requires a bit more muscle to get it up and tweaked. Granted, this rocket ship wasn’t designed with lower speeds in mind, and it shows with a list of Personal Records that our various testers achieved.

Another downside is that the bike does have more stuff to go wrong. Whether you’re one of the unlucky riders dropping chains – which we did three times before the service bulletin addressed the issue – or not, more moving parts, extra chain links, and more nooks and crannies all mean more chances for things to go wrong.

Trek Slash 9.9 X0 AXS Gen 6 Mountain Bike Review

CLIMBING | Along with the above concerns, the climbing performance of the Gen 6 Slash certainly isn’t what its outgoing sibling offered. Since taking possession of the Trek Slash 9.9 XO AXS we’ve had four riders put time on it. Two of which owned previous generation Trek Slashes. All riders agreed, like Trek claims, this bike is a definite 70/30 bike, and the climbing performance is tolerable in certain situations like fire roads and smoother trails, but can be a struggle on more steep, technical trails with larger obstacles that want to eat your momentum.

The weight is noted, and while the drag may be a claimed 3%, it felt a bit closer to 10% in practice. That could be exacerbated by the lengthening rear end – yes, the same thing that makes high pivots so great, also works against it.

It’s been a while since we graduated but, we think someone smart once said something about actions having reactions, but we didn’t pay close attention in school so maybe we’re making it up. Either way, when speeds are low, the grade steep and effort high, we found that the rear end could “stall” as we tried to pedal over roots or rocks, sucking our energy and momentum in the process. Much the way the rear end grows to get up and out of the way of an impact while descending, as you climb and hit an obstacle, the front continues to creep up the hill as you grind away at the pedals. However, the rear wheel goes backwards before going up and that delay can make it feel like you’re pedaling harder to get up and over that obstacle, which means more energy and slower times. Of course, this bike wasn’t designed to race up the hill, it’s meant to go down. If your energy is spent on the way up, however, it could be worth considering you may be more fatigued when that race timer starts.

FINISH AND VALUE | Now, as amazing as the bike is, we did in fact drop the chain three times over the six-month test period we had. Since the repair, we didn’t drop the chain, however we only had a few rides on it before winter hit, so we can’t say with 100% confidence it’s gone, but we are pretty certain that with the updated spacing and especially the new idler wheel, we’d be in good shape. You may want to wait until the updated idlers hit, hopefully February of 2024, but in the meantime the chain dropping issue may not be quite as bad as commenters may have you believing.

The rest of the bike is a nicely put together package. Trek paint had some years known for being a bit, soft we’ll call it, and while it’s still not as durable as we’d like, it’s a lot better. Though we’d recommend a frame wrap, of course, we’d recommend that on any bike, so maybe not a surprise there. If you stop, look closely and examine the details of this bike, it does look very nice, has quality bits, nice hardware and a very classy overall appearance. Trek have done a nice job making this a drool-inducing bike.

The Wolf’s Last Word

If you prioritize downhill capabilities over all else and want a bike that will allow you to ride faster and send it deeper, the Trek Slash is a serious contender. As it sits right now, the Trek Slash is one of our favorite bikes of the year and while the climbing performance does require more patience or strength, the smoothness over chatter and way this bike descends would have us seriously considering this as our go-to long-travel rig if we weren’t going to purchase a full-on DH bike.

Price: $9,399
Weight: 36.4lbs


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