trek slash 8 suspension calculator

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Trek Suspension Calculator

By Hafiz Mehran - Updated 1 day ago

As an avid cyclist, you know that the key to an exhilarating ride lies in...

As an avid cyclist, you know that the key to an exhilarating ride lies in a well-tuned bike suspension.

Whether you’re tackling rugged trails, conquering downhill descents, or embarking on epic cross-country adventures, getting your suspension dialed in is essential for a smooth and controlled ride.

Discover the secrets to a smoother ride with the Suspension Calculator . Achieve the ideal setup for your biking needs effortlessly.

Understanding the Importance of Bike Suspension

Before we delve into the workings of the Suspension Calculator, it’s essential to grasp the significance of bike suspension.

The suspension system on your bike is responsible for absorbing shocks and vibrations, ensuring a comfortable and balanced ride.

It comprises front suspension forks and rear shocks, which can be adjusted to suit different riding styles and terrains.

Step 1: Preparing Your Data

To get started with the Suspension Calculator, gather the necessary information.

You’ll need to know your own weight, as well as your bike’s weight. Measure the suspension travel, which refers to the maximum distance the suspension can move.

Determine the sag percentage, representing the amount the suspension compresses under your weight.

Step 2: Access the Bike Suspension Calculator

The Suspension Calculator is typically available online through various cycling websites and tools.

Access the calculator via your web browser, and you’ll be greeted with an intuitive interface designed to simplify the process.

Step 3: Input Your Data

Once you’re on the calculator page, you’ll find clearly labeled input fields awaiting your data.

Enter your weight and your bike’s weight in kilograms, and add the suspension travel in millimeters.

Provide the sag percentage as well, and select your preferred riding style from the dropdown menu.

The calculator accommodates trail riding enthusiasts, downhill daredevils, cross-country adventurers, and enduro warriors alike.

Step 4: Initiating the Calculation

With all your information neatly entered, it’s time to set the wheels in motion.

Click the “Calculate Suspension” button, and let the calculator work its magic.

Behind the scenes, complex algorithms and formulas take into account the gathered data to generate personalized suspension recommendations.

Step 5: Deciphering the Results

In just a matter of seconds, the Suspension Calculator will present you with your tailored suspension setup.

The results will include the recommended PSI (Pounds per Square Inch) for your front suspension fork and rear shock.

This ensures your suspension is perfectly tuned to your weight and riding style, delivering optimum performance and comfort.

Step 6: Applying the Recommendations

Now comes the exciting part – putting the calculator’s recommendations into action.

Locate the air valve on your suspension fork and shock, and use a high-quality suspension pump to adjust the air pressure according to the recommended PSI.

This step is crucial as it ensures the suspension responds optimally to your weight and riding style.

Step 7: Fine-Tuning Your Ride

With the recommended PSI in place, it’s time to set the sag percentage.

This step involves compressing the suspension to achieve the desired sag based on the calculator’s suggestions.

Enlist a friend’s help to support your bike while you sit on it in your normal riding position.

Measure the suspension’s compression, and adjust the preload or air pressure accordingly until you hit the desired sag percentage.

Step 8: Hitting the Trails

Your bike’s suspension is now dialed in, courtesy of the Suspension Calculator’s precision recommendations.

Take your newly adjusted bike for a test ride, exploring various terrains and trail features.

Pay close attention to how your suspension handles bumps, berms, and jumps.

Based on your riding experience and feedback, consider making minor adjustments to find the perfect setup that matches your preferences and riding style.

The Bike Suspension Calculator is a game-changer for cyclists seeking an optimized and personalized suspension setup.

By harnessing advanced algorithms and user input, this powerful tool provides riders with tailored recommendations for their weight, riding style, and suspension travel.

Implementing these suggestions results in enhanced comfort, control, and overall performance on every ride.

Keep in mind that suspension tuning is an iterative process.

As your riding style evolves or your physique changes, don’t hesitate to revisit the calculator to ensure your bike’s suspension remains in perfect harmony with your needs.

So, why wait? Let the Suspension Calculator be your guide as you embark on a journey to mastering bike suspension and taking your rides to new heights of exhilaration and enjoyment.

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**maintenance, trek suspension setup calculator.

Thankfully, Trek have taken a step towards making the setup much easier, with the launch of its suspension setup calculator.

Tap in your weight, choose the model of bike and year of production, and it spits out the suggested air pressure. It also tells you how many clicks of rebound and compression the company recommends for your bike.

Clearly, it’s only any good to Trek owners. If you’ve got a Trek, head this way  www.trekbikes.com/us/en/resources/suspension_setup

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• TF Tuned Glossary
• Mount Kits and Bushings for Rear Shocks

Trek Shock Guide

• Performing a Lower Lube
• Basic Air Can Maintenance
• Cleaning Your Suspension
• Removing Your Forks
• Fitting Your Forks
• Removing Your Shock
• Fitting Your Shock
• DIY Servicing / Manufacturers Manuals
• Vorsprung Installation Manuals

This is for guidance only. You are responsible for verifying clearance on your frame. Mount kit measurements should be checked (especially for older frames.)

You can find Trek bolts here .

Shock mount hardware is available here .

Lower Shock Axle – 599899           Upper Shock Axle – 599898

Additional bolts are only required for Thru-Shaft to standard shock conversion.  For DRCV conversion you will need a “DRCV retrofit kit”

SHOCK COMPATIBILITY (GEN 6)

Push* -  Push do not offer ElevenSix for this frame 

Fast* - We are yet to confirm clearance of the Evo variant 

SHOCK COMPATIBILITY

Trek Rail - Gen 3:

Lower Shock Axle – 5258210        Upper Shock Axle – 5258209       

Trek Rail - Gen 2:

Lower Shock Axle – 599900           Upper Shock Axle – 599898

Trek Rail - Gen 1:

Additional bolts are only required for Thru-Shaft to standard shock conversion.  

Fox X2* - In theory this shock fits, however, it is “too close for comfort” and any flex in the frame may cause the shock to collide with the frame.  We would recommend against fitting X2.

Push* - Once upon a time Push made an ElevenSix SS (side stack) with offset adjusters and a perpendicular reservoir which allowed the shock to clear the frame.  Any other generation of the ElevenSix will not fit.

Marzocchi* - We are yet to confirm whether the Marzocchi Bomber Air is compatible.

Fast* - Only the standard Fenix Enduro (not Evo) shock with a perpendicular reservoir will fit.  

Lower Shock Axle – 540755           Upper Shock Axle – 540755

RockShox Deluxe* - might not perform very well/ consistently on a long travel ebike due to lower overall oil volume

Trek Slash (2021+):

Lower Shock Axle – 5258210        Upper Shock Axle – 5258209

Trek Slash (pre-2021):

SHOCK COMPATIBILITY (2021 & NEWER)

RockShox* - Standard Super Deluxe Air does not fit due to lock-out lever interference in the last 1/3 of the travel 

SHOCK COMPATIBILITY (2022 & NEWER)

Coil Shocks** - this frame is not very progressive and it is much better suited for air shocks

Push* - Push do not offer ElevenSix for this frame

Ohlins Coil* - Only with transverse casting

Ohlins Air* - This shock will likely fit, however, we are yet to confirm this

Intend* - This shock will likely fit, however, we are yet to confirm this

CaneCreek* - We are not sure due to end eye design

Marzocchi Coil* - IFP reservoir will need checking for clearance!

Marzocchi Air* - Similar in design to Float X, however, it still needs checking for clearance

Fast* - Needs checking for clearance at full travel, the Evo version of the shock might not fit

Super Deluxe Thru-Shaft (C1 2021+)

The RockShox Super Deluxe Thru-Shaft shock is a proprietary shock designed explicitly for Trek Bikes and not available on any other frame manufacturer’s bikes.  The Thru-Shaft is fitted on a range of Trek frames including the Slash and the Rail.  

Most mountain bike shocks use an internal floating piston (IFP) design. The IFP sits between the oil and gas [typically nitrogen] inside the shock. When you hit a bump, the shock damper shaft displaces the oil as it moves through the shock, pushing against the IFP and compressing the gas below.  The IFP returns to its position when you are over the bump and the oil pressure is reduced. 

The idea behind the Thru-Shaft design is to remove the perceived lag created by using an IFP. Instead, the design introduces a secondary damper rod to account for the change in oil volume, and the damper shaft ‘exits’ the bottom of the shock.  

On paper, it may seem like a great idea, but the Thru-shaft design has suffered reliability issues.  A rod protruding from the shock requires an additional seal to retain the oil in the damping circuit - and in practice, another seal means another point of possible failure.  

As production of these shocks is limited to Trek Frames this product is less well supported in terms of spares and parts than another more widely available/ equivalent suspension.  This means that these shocks are generally more challenging, or sometimes even impossible to service or repair.

On balance and in our experience, the performance and maintenance issues of the Thru-Shaft outweigh the stated benefits of this suspension design.

CAN I REPLACE MY ROCKSHOX THRU-SHAFT SHOCK WITH A STANDARD EYELET SUPER DELUXE AIR/ COIL SHOCK?

The frame/ shock clearance varies between frames and frame model years - please refer to the compatibility tables on top of the page for per-frame & model year compatibility.   The reservoir on the Thru-Shaft shock is placed much higher, towards the upper eyelet (trunnion), and offset to one side in relation to the IFP reservoir on a standard Super Deluxe to improve the frame clearance.   See the image below for a comparison .

CAN I REPLACE MY ROCKSHOX THRU-SHAFT SHOCK WITH A DIFFERENT TRUNNION?

No, not without drastically affecting the bike’s geometry. Despite the Thru-Shaft shock using trunnion mounts, it is a 230mm eye-to-eye shock.   See the image below for a comparison .

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Trek Suspension Calculator?

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Just picked up a new Ex9 and was playing with the suspension. After a quick look online, I found this guy: Suspension setup - Trek Bicycle Has anyone used the Trek calculator? Any idea how accurate it is? For me it's showing a very high rear shock pressure (I have always been on RS and have never set a Fox fork/shock). I've been working up to a good pressure but haven't had a chance to dial it in - the calculator is almost 100 psi higher then where I am at right now working up from a 25% sag. Granted, the shock is still soft right now. Curious to hear others experience.  

I referenced Trek's suspension calculator when I got my '14 Slash 7. I also found it to "erroneously" skew towards higher air pressures, particularly for the fork (160mm RS Pike). I don't blame Trek at all. There is no magic equation for suspension setup. The only way to get dialed-in is by trial (trail) and error, with your handy shock-pump by your side. That, and initially setting a desired sag amount. There are too many variables at play for a one size fits all solution: Riding style, level of finesse, terrain, body position on the bike. Not to mention how much the suspension action can vary based on how new/old, clean, or lubricated a component is.  

I have found the calculator to be very accurate for what a good set up is. I vary it a little bit, but it is pretty close to being optimal for me. It is also close to the sag settings....not sure how you could be 100 PSI off...something is not right. Make sure you have the shock pump screwed all the way in tightly , so you see the pressure go up twice on the shock pump as you are screwing it in (dual chambers in the shock).  

Haymarket said: ...something is not right. Make sure you have the shock pump screwed all the way in tightly , so you see the pressure go up twice on the shock pump as you are screwing it in (dual chambers in the shock). Click to expand...

Thanks for the feedback. My fork was dead on to what I had dialed in (well, 1 click off on the rebound) but the shock is quite a bit off. I'll continue to work up in PSI from my starting point set on the sag. It bugged me that they didn't show the fork/shock that should have come on by bike (and it was providing numbers for). The picture for the bike was right. I might crank it up and just try it too - it's below the max pressure by quite a bit so it couldn't hurt.  

I also obsessively monitor the position of the rubber o-rings on the fork stanchion and shock body, to know how much travel is used in a given run/ride. If the o-ring is gone, just use a zip tie.  

I have a stache 7 and it's not in that calculator. Thumbed around in the app for a bike that has a similar front fork and found the 2014 Fuel EX 6 29 which has a Recon GOLD but the stache has the Silver. The App Says 140psi for my weight (215) which is right in line with the following PDF chart from SRAM/Rockshox https://www.sram.com/sites/default/..._air_spring_chart_gen_0000000004148_rev_a.pdf no idea what to run for rebound. Can only feel 5 clicks on the Recon Silver. I went ahead and put it at the click 3 from turtle speed. purchased the bike a week ago and the LBS had it setup a little low on air at 110psi and full fast. Maybe it leaked down, maybe it didn't. Next ride will be at 140psi unless the sag looks totally off.  

I recently acquired a Fuel Ex 8 and I have found the recommended settings spot on for me though I have tried varying my weight up or down 2 or 3 kgs and that can make quite a difference to the recommended settings. However my 1st attempt was a huge FAIL as I keyed in my weight in kgs but calculated the settings in lbs which of course was far too soft. The ride felt terrible and I began regretting my purchase LOL. I don't regret it now that I have the suspension dialed. The ride is sweet!. :thumbsup:  

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Trek Shock Upgrades - Thru Shaft to Standard

Posted on March 09 2023

• Trunnion to Pin 69mm  Available here
• 54mm x 10mm Hardware Fox Available here
• 60mm x 10mm Hardware Fox Available here
• 54mm x 10mm Hardware Rockshox  Available here 
• 60mm x 10mm Hardware Rockshox Available here
• 50mm x 10mm Offset Hardware Fox   Available here
• 50mm x 10mm Offset Hardware Rockshox  Available here 

Commonly used for the lower shock mounting bolt on Slash (2021+), Fuel EX (2021+), and Trek Rail 2022+. Used in conjunction with 40mm x 10mm mounting hardware. Trek Part #5258210

• Trunnion to Pin 55mm  Available here
• 40mm x 10mm Hardware Fox Available here
• 40mm x 10mm Hardware Rockshox Available here

Commonly used for the lower shock mounting bolt on Fuel EX and Remedy and Slash (2017-2020). Used in conjunction with 50mm (49.78) mm x 10mm Offset mounting hardware. Trek Part #599899

• Trunnion to Pin 65mm   Available here

Commonly used for the lower shock mounting bolt on Trek Rail 2020/21,  Fuel EX Carbon (2017). Used in conjunction with 50mm (49.78) mm x 10mm Offset mounting hardware, or 40mm x 10mm hardware. Trek part # 540756 (16mm head for earlier frame), or 18mm head for later (2021+) frames. 

• Trunnion to Pin 59mm (18mm head)   Available here
• Trunnion to Pin 59mm ( 16mm head)   Available here
• 40mm x 10mm Hardware Fox   Available here
• 40mm x 10mm Hardware Rockshox   Available here

Notice an error? Let us know!  

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Trek Slash 9.8

• AUS $ NZD $ USD $ CAD $ GBP £ EUR €

Colour / Trek Black/Roarange

Size / 15.5 in., 17.5 in., 19.5 in., 21.5 in.

Weight / 29 lb 11.1 oz (13,470 g)

At a glance

EVO link suspension, ABP (Active Braking Pivot), Straight Shot frame design, Knock Block frame defense, Mino Link adjustable geometry, Control Freak internal cable routing, 1x-specific stays

Where To Buy

"The Slash set the new benchmark for long-travel 29ers not long ago, and 2018's version attempts to meet the same standard. This one is stiff, light, and an excellent option for long adventures."

Specifications.

• Frame OCLV Mountain Carbon main frame and seatstays, alloy chainstays, Carbon Armor
• Fork FOX Performance 36 Float, GRIP 3-position damper, E2 tapered steerer, Boost110, G2 Geometry, 51mm offse, 160mm
• Shock RockShox Deluxe RT3, RE:aktiv with Thru Shaft 3-position damper, tuned by Trek Suspension Lab, 230mm x 57.5mm
• Hubs Bontrager Line Elite 30, 108T Rapid Drive, Boost110 front, Boost148 rear
• Wheels Bontrager Line Elite 30, Tubeless Ready (tubeless strips included, valves sold separately)
• Wheel Size 29"
• Tires Bontrager SE4 Team Issue, Tubeless Ready, Core Strength sidewalls, aramid bead, 29" x 2.40"
• Chain 433mm, N/A, SRAM Descendant 7k Eagle, 32 tooth, Direct Mount, X-Sync, SRAM GX Eagle
• Crank SRAM Descendant 7k Eagle
• Bottom Bracket 352mm, PF92
• Rear Derailleur SRAM GX Eagle, Roller Bearing Clutch
• Shifters SRAM GX Eagle, 12-speed
• Brakeset SRAM Guide RS hydraulic disc, SRAM Guide RS hydraulic
• Handlebar Bontrager Line Pro, OCLV Carbon, 35mm clamp, 27.5mm rise, 780mm width
• Saddle Bontrager Evoke 2, chromoly rails
• Seatpost Bontrager Drop Line, internal routing, 15.5": 100mm travel, 17.5": 125mm travel, 19.5" and 21.5": 150mm travel, 31.6mm, Standard single bolt, 31.6mm, Standard single bolt
• Stem Bontrager Line Pro, Knock Block, 35mm clamp, 0° rise, 50mm length
• Grips Bontrager Rhythm, dual lock-on
• Headset Knock Block Integrated, sealed cartridge bearing

Q: How much is a 2018 Trek Slash 9.8?

A 2018 Trek Slash 9.8 is typically priced around $5,500 USD when new. Be sure to shop around for the best price, and also look to the used market for a great deal.

Q: Where to buy a 2018 Trek Slash 9.8?

The 2018 Trek Slash 9.8 may be purchased directly from Trek .

Q: How much does a 2018 Trek Slash 9.8 weigh?

A 2018 Trek Slash 9.8 weights 29 lb 11.1 oz (13,470 g).

Q: What size wheels does the 2018 Trek Slash 9.8 have?

The 2018 Trek Slash 9.8 has 29" wheels.

Q: What size 2018 Trek Slash 9.8 should I get?

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• Rider Notes

2022 Trek Slash 8 Gen 5

A 29″ aluminum frame full suspension enduro bike with high-end components.

Manufacturer Price

For This Bike

View more similar bikes →

Based on frame geometry and build specs.

A bike with lower gearing will be easier to ride up steep hills, while a higher top end means it will pedal faster down hills.

Slash 8 Gen 5

Similar Bikes

(descending)

Add custom gearing

Based on build material and quality level of the frame, fork, wheelset, groupset, suspension system, and more.

Oct 2023 · Dario DiGiulio

Trek did a very good job making the Slash a quiet bike, then seemingly lost the plot when they specced a hard rubber chainslap protector that does little to mitigate the drivetrain noise in bumpy terrain.

Excellent geometry and balanced ride

Composed, capable, and predictable suspension

Climbs well for such a downhill-focused bike

Excels in challenging terrain

Chassis may be too stiff for some

Chain drop issues due to improperly spaced lower idler (fixed)

Stock chainstay protector did very little to manage noise

Read Review

The all-new Trek Slash is beefed up in celebration of its sixth iteration. This fresh design features an oversized, 19-tooth idler pulley and a high-pivot rear suspension configuration for the first time in the model’s lineage. Travel has been increased to 170 millimeters, pushing it further into the all-out, winch-and-plummet ethos that so many enduro bikes seem to be gravitating to. Our 9.9 version was spec’d with Bontrager’s RSL integrated handlebar and stem, a SRAM T-Type XO drivetrain, and the all-new RockShox Vivid Ultimate rear shock. The previous Slash was an impressive bike. It was impressively light for an enduro bike and was surprisingly efficient to pedal around all day. The new Slash Gen 6 leans more heavily toward the chairlift and shuttle culture side of the mountain bike world with some extra heft and additional pulleys in the drivetrain. However, with the oversized pulley and lighter casing tires, I found the Slash to climb the most efficiently of any high-pivot bike I’ve reviewed thus far. I attribute this mostly to the large, 19-tooth upper idler.

The Trek Slash 9 9 shines on the steeps and excels in the rough, making it an almost perfect rig for enduro racing. Read the full Trek Slash 9.9 XO1 Review here.

Steep terrain crusher

Rough terrain performance

Not the best climber

Ineffective drain tube

Apr 2022 · Alan Muldoon

The Trek Slash 9.8 XT is an enduro bike with progressive geometry and 29er wheels and 170/160mm of travel, and offers a performance that seriously impressive. Good enough to make it on our list of the best enduro mountain bikes? Absolutely. It’s good enough to score a  10 out of 10; a rare feat. Trek Slash 9.8 XT need to know: Mino Link geometry adjustment allows for a 27.5in Mullet setup KnockBlock 2.0 offers an increases the steering angle from 58º to 72º and can be removed if needed A bash guard on the MRP chain guide helps protects the 30t XT chainring RockShox Super Deluxe Ultimate shock sports ThruShaft technology to control the 160mm travel We took the Trek Slash 9.9 XO1 for a first ride when it launched last year, and while the 2022 bike looks remarkably similar, right down to the frame colour of the bike we featured last time, there are several differences. The main one being that the XT equipped bike is £1,500 cheaper and there are changes to the specification that reflect its lower price. You get a full Shimano XT drivetrain and 4-piston XT brakes, rather than SRAM XO1. You also get a RockShox Zeb Select+ fork rather than the Ultimate, while the Bontrager Line Carbon 30 wheels switch to the alloy version. Downgrades? Yes, but none that should detract from the underlying ride quality of the Slash. The most important thing is that the OCLV carbon frame remains unchanged, so you still benefit from all of the advances in the frame geometry and suspension that Trek introduced last year. Updates that saw the addition of downtube storage, the head tube angle getting slacker, the seat tube steeper and the reach longer. Trek also made the suspension more progressive, and increased rear travel by 10mm to 160mm. All positive changes then. Trek Slash 9.8 suspension Trek has always been a big proponent of proprietary suspension components. As such, the RockShox Super Deluxe Ultimate shock on the Slash 9.8 XT features Trek’s ThruShaft technology and it’s the exact same shock that comes on the flagship model. This design eliminates the need for a high pressure IFP (internal floating piston) and in simple terms, this allows for lower breakaway resistance and improved sensitivity. And because the damper shaft passes straight through the shock body, it needs an extender mount and a small hole in the frame to accept the ThruShaft at bottom out. Sounds complex? Well it is, but thankfully setting up the suspension on the Slash is as easy as 1, 2, 3. Sag gradients make it simple to dial in the correct air pressure, and in the open setting the shock has three low-compression settings for fine tuning the response to pedal inputs or the style of terrain you’re riding. Also if you ever want to fit an aftermarket shock, that’s still possible as the Slash uses a 230×62.5mm metric shock size, you’ll just need different lower mounting hardware. Setting up the suspension …Continue reading »

Fast, fun and efficient. Tight, reactive ride. Progressive geometry. Versatile, composed. A do-it-all bike

XL would benefit from a steeper seat angle

Apr 2021 · Robin Weaver

The Slash 8 strikes the perfect balance between a fun and lively feel, and ultimate chaos-calming composure

Easy to ride, very natural feeling geometry

Great kit for the cash

Easy to throw about yet still calm and stable when it needs to be

Seriously impressive suspension

Tyres aren’t the best in damp mud

Mar 2021 · Lydia Tanner

The Trek Slash has been 29-inch-only since 2016, and the 2021 version is evidence of its head start in the big-wheel enduro category.

Superb high-speed stability

Great traction in variable terrain

Supple and generous-feeling suspension

Less maneuverable at slow speeds

A lot of bike to get back up the hill

Riding a bike like the Slash over the winter on the North Shore is a rough test scenario, but Trek's newest long travel trail bike has proven up to the task...

Feb 2021 · Guy Kesteven

We took the Trek Slash 9.9 X01 to our toughest local trails to see how its new shape and unique shock translate to the real world

Phenomenal rear suspension

Awesome aggro geometry

Precision accuracy

High control cockpit

Internal storage

Efficient pedaling

Threaded BB

Optional steering lock

More confident with switched tires

ZEB fork requires some patience

Deserves better wheels

Short dropper on small sizes

Seriously grounded rather than playful

First added March 15

Last updated August 16

Not listed for 12 days

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Trek Slash 8 Gen 6 review | Enduro Bike of the Year contender

Trek’s high-pivot, big-travel Slash 8 boasts good value and promises a lot on the trail

Laurence Crossman-Emms / Our Media

Robin Weaver

Composed feel at speed; climbs really well; great geometry; shock tunes helps it feel lively and playful; solid spec for the money

Tyres struggle in mud and aren’t tough enough; fork requires careful tuning to compensate for performance limitations

Trek has historically done well in our Enduro Bike of the Year category, with the Slash taking top honours back in 2021.

The latest Slash Gen 6 frames feature a high-pivot suspension design to deliver the 170mm of rear-wheel travel, come with a mixed-wheel setup as standard and offer up plenty of suspension and geometry adjustment.

On top of that, the new Slash also gets the standard lower, longer and slacker treatment in a bid to make this a genuine World enduro race winner.

The Slash 8 is the cheapest of the seven-bike Gen 6 line-up, uses an aluminium frame and comes with some solid parts from the likes of Shimano and Fox.

Although it's the cheapest of the eight bikes in my Enduro Bike of the Year test, it really packs a punch on the trail, with a ride that stands out for all the right reasons.

It’s sprightlier than expected and more playful too, but get stuck into the really rough stuff and it’s impressive just how well the rear end smooths out the trail.

Push too hard, though, and some of the spec choices start to hold this otherwise impressive rig back.

Trek Slash 8 Gen 6 frame and suspension details

The Slash 8 Gen 6 is made from Trek’s Alpha Platinum Aluminium, sports a plethora of rubberised driveside frame protection to help quieten chain slap and has under-belly guards to fend off rock strikes.

High-pivot designs are nothing new to Trek (the Diesel downhill bike was released more than 20 years ago), though they tend not to feature on bikes that need to be pedalled a lot.

That’s all changed with the latest Slash Gen 6 frame, which – you guessed it – now sports a high main pivot.

The bike continues to use Trek’s ABP (Active Braking Pivot) suspension layout, which sees the chain and seatstay pivot concentric to the rear wheel axle. That equates to a single pivot with a linkage-actuated rear shock.

The high main pivot creates a rearward axle path, designed to deal better with momentum killing square-edge hits.

In total, Trek says this moves a maximum of 18mm back from its starting point (growing the effective chainstay measurement) at around 135mm into the 170mm of rear-wheel travel before continuing to arc upwards and forwards for the remainder.

With 30 per cent sag, it’s estimated that the effective chainstay length will have increased by 11mm, sitting at around 440mm.

A massive upper idler helps to mitigate pedal kickback – a result of the rearward axle movement.

The lower idler cog is designed to take tension off the rear derailleur. This is not only to help it continue to shift properly and more efficiently, but to increase suspension sensitivity (because the lower section of the chain isn’t trying to extend the derailleur against its clutch mechanism).

Sizes small through to large need a standard 126-link chain, while the XL requires an extra-long 128-link chain.

To ensure the Slash Gen 6 can work with a coil-sprung shock , there’s a flip chip in the lower shock mount that enables you to increase the level of progression across the 170mm of travel from 20 to 25 per cent.

There’s also some integrated down tube storage for stashing essentials out of the way.

Trek Slash 8 Gen 6 geometry details

Trek offers the Slash Gen 6 in small, medium, medium/large, large and extra-large sizes.

The size small comes with 27.5in wheel front and back, while all other sizes use a 29in front and 27.5in rear wheel as standard.

There’s the option to switch to a larger rear wheel, although you’ll need to purchase a different lower shock mount to do so (£29.99).

Likewise, if you’re keen on altering the head angle, Trek sells aftermarket angled headset cups (plus or minus 1 degree) for £27.49.

I measured the Slash 8 to sport a slack head angle of 63.4 degrees, with a front centre of 790mm.

The seat tube angle is steep at 77.7 degrees, and the effective top tube quite compact for a size medium at 578mm.

Reach isn’t the longest at 448mm, but thanks to the compact seat tube lengths (400mm on the medium) across the size range, many riders will be able to size up if they’re looking for a roomier ride.

On paper, the Slash’s chainstay length looks really short at 429mm, but remember, as the bike drops through its travel, the rear axle moves backwards, effectively increasing this figure.

Trek Slash 8 Gen 6 specification

Trek has been smart with where it has spent the budget on the Slash 8.

Shimano XT gearing is great to see on this level of bike, and it’s no issue that this has been made possible in part thanks to the use of the lower-spec Deore crankset.

The brakes are also from Shimano, in the shape of Deore M6100 levers and four-piston M6120 calipers.

Taking care of the 170mm of travel at the front is a Fox 36 Rhythm fork, which uses the brand’s cheapest and most simplistic GRIP damper with limited adjustment compared to the pricier GRIP2 equivalent found on more expensive mountain bike forks .

This is matched to a Float X Performance rear shock.

In-house parts brand, Bontrager takes care of just about everything else, including the bar and stem. Unlike the pricier Slash 9.9 X0 AXS T-Type , it doesn’t use Trek's one-piece bar and stem, which is a plus in my eyes.

Bontrager also provides the wheels and XR5 Team Issue tyres.

All in, the medium Slash 8 Gen 6 on test weighed 17.01kg without pedals.

Trek Slash 8 Gen 6 ride impressions

I tested the Slash 8 on a wide variety of trails dotted around the Forest of Dean, South Wales and BikePark Wales.

These spanned from flowy jump lines through to hand-cut, steep, technical, natural descents, along with plenty of high-speed, rough-and-ready bike park tracks thrown in for good measure.

This enabled me to develop a thorough understanding of what the Slash 8 is good at and where it struggles.

Trek Slash 8 Gen 6 setup

Setup was quite straightforward, settling on 30 per cent sag for my 68kg weight with 147psi in the spring and the rebound damping left fully open. However, the fork became more of a puzzle as time progressed.

Initially, I settled on 71psi in the fork’s air spring, with only a couple of clicks of rebound damping wound on (from fully open). This offered masses of comfort and a decent level of traction.

As time went by and I felt more comfortable on the Trek, I had to increase the spring pressure and rebound damping to try to raise the level of support on offer.

I finished with 75.5psi in the air spring and no volume spacers.

Trek Slash 8 Gen 6 climbing performance

The Trek’s seated position is upright and comfortable, thanks to the steep seat tube angle.

It’s not particularly stretched out, though, due to the relatively short effective top tube and stumpy 35mm stem.

I wasn’t ever uncomfortable and didn’t feel cramped, but I noticed that compact position occasionally when scaling steeper, technical inclines. At 172cm, I think I could comfortably go up a frame size and negate these issues, though.

However, that’s not the headline here. What takes all the attention is how well this long-travel big hitter pedals.

Get cranking and the rear shock stays spookily still while you tick off the vertical metres. It helps that the tyres roll pretty quickly, too, limiting drag and injecting a bit of get up and go into proceedings.

With so little movement from the back end, you can leave the shock’s low-speed compression lever well alone because you don’t need it.

On every climb I tried, the Slash 8 felt the sprightliest and most energetic when pointed uphill, which is quite surprising considering its weight. It’s only when faced with soft mud that progress is stifled, due to the rear tyre lacking enough bite to generate grip and spinning up easier than others.

Trek Slash 8 Gen 6 descending performance

That energetic feel translates instantly to the trail when descending, too.

Trek has nailed the rear shock tune with this bike, producing a seriously capable bump gulper that helps generate traction when needed, but never sucks the fun out of even the tamest of tracks.

The fast-rolling tyres play a part in all of this, but the comfortable, well-balanced suspension helps the Slash remain playful, agile and, most importantly, fun when skimming through undulations and gapping rollers.

Speed seems to come easily, even when boosting in and out of slow-paced turns. Pick-up from the rear hub is quick and dumping gears quickly thanks to the precise XT shifter and derailleur is rapid when you find yourself wanting to inject even more speed to proceedings.

Square-edge what?

Pummel into faster, rougher sections of trail and the back end of the Slash really starts to shine.

The high-pivot design does a great job of scalping the peaks of the ugliest square-edge hits, helping you to stay online and composed at speed.

It’s this sensation that builds confidence and encourages you to ride faster. However, this is when you’ll start to reach the limits of the fork and tyres.

The Fox 36 Rhythm fork, with its GRIP damper, is one of the comfiest suspension forks on the market. But push it hard and you’ll be left puzzling over how to best balance that comfort with support.

My initial starting point delivered a beautifully supple ride, but lacked support when riding faster tracks, causing the front end to drop away with higher-load compressions and landings, and upsetting overall balance.

Upping the spring pressure and adding volume spacers helps here, but reduces overall comfort. The basic compression dial doesn’t exactly enable fine-tuning.

To unlock the full potential of the Slash 8, you’d be best to get the fork professionally tuned (roughly £120 for a service, plus £50 for custom tuning) so it can better handle being ridden hard without compromising that impressive comfort too much.

Similarly, I found myself incrementally adding pressure to the tyres , too, because they’re not as supportive or as tough as the best mountain bike tyres . This was largely because I found myself burping the rear tyre all too easily.

Thanks to the supple suspension, I didn’t find this to impact comfort too much, but you can feel the effects in terms of traction, especially when tackling anything remotely wet.

Swapping to your preferred tyre combo from the get-go should be high on your to-do list. You might want to ditch the chunky, wide-diameter grips while you’re at it.

Mega momentum

Despite those niggles, I never failed to have fun riding the Slash 8 and was always impressed by how well it could maintain speed.

On rough, high-speed tracks littered with rocks ready to sap your speed, the Trek always managed to retain incredible pace.

The back end beavers away tirelessly to isolate you from the worst impacts, enabling you to remain centred on the bike and focused on your line.

When speed started to dwindle, I had sufficient support, enabling me to pump undulations and compression in a bid to boost speed. However, I’d argue the Slash isn’t as direct and punchy in that sense as some of its rivals.

The geometry isn’t as lengthy or as raked out as some, but it still feels a confident bike to ride, even more so if you swap to grippier tyres.

Through the turns, the low 340mm bottom bracket helps to keep things suitably stable, while the suspension tracks the terrain almost effortlessly.

How does the Trek Slash 8 Gen 6 compare?

As the second most expensive bike within the Enduro Bike of the Year test, I’m going to compare the Slash 8 to the Transition Spire Alloy NX.

The Spire costs £50 more and comes with the same rear shock and a Marzocchi Z1 fork with the same GRIP damper.

But while the Slash features pricier Shimano XT gearing, the Spire has SRAM’s NX Eagle transmission. This proved to be clunkier and more problematic to keep running smoothly after months of riding in grim conditions.

The Spire suffers from the same fork issues as the Slash – impressive comfort but lacking in high-speed support when you really start pushing the bike.

Both bikes climb well, but the Slash feels a little punchier when grinding its way uphill.

On the descents, while the Spire offers a smooth ride, it can’t quite compete with the supple high-pivot bump-eating back end of the Slash.

The Slash is, overall, a comfier ride, too, with more feedback coming through the front end of the Spire when battering through repeated hits.

Enduro Bike of the Year 2024 | How we tested

The expectations resting on the shoulders of any enduro bike couldn’t be heavier. Creating a bike capable of tackling just about any trail revolves around smart choices and compromise.

In the simplest terms, enduro riding and racing is all about winching your way up to the top of a hill or mountain, then tackling an often-challenging descent.

These bikes are designed to excel at downhills.

How a bike handles the climb isn’t the be-all and end-all when it comes to overall performance, but pedalling efficiency and seated geometry still need to be factored in.

When it comes to geometry, we’re looking for stability and composure, but without dulling playfulness and agility.

A balanced suspension system creates a stable ride, but engineers also need to factor in the right amount of support for the rider to push against when pumping the terrain, and enough sensitivity to ensure the tyres can maximise traction on just about any surface.

Over a three-month period, all the bikes in this category were ridden back-to-back, as well as in different orders, in a bid to eke out every difference between them.

The trails in question varied from steep, natural downhill tracks and forest singletrack through to the high speeds and hefty impacts of BikePark Wales.

Our Enduro Bike of the Year contenders

• Santa Cruz Megatower C R
• Transition Spire Alloy NX
• Ibis HD6 XT
• Kona Process X CR
• Marin Alpine Trail XR
• YT Capra 29 Core 4
• Cube Stereo One77 C:68X TM 29
• Trek Slash 8 Gen 6

Trek Slash 8 Gen 6 bottom line

The Trek is a seriously smooth operator and really impressive for the cash.

Supple, well-balanced suspension and some really solid gear choices make it a formidable bike on the hills.

The fact that it has so much travel and a high-pivot, but climbs like a much lighter, shorter-travel machine is a massive bonus.

Push hard and the fork can’t keep up with the shock – and lacks the same level of composure at really high speeds. Meanwhile, the tyres are best suited to trail-centre pootling rather than full-on enduro riding and racing.

Swap the tyres and get the fork tuned to optimise performance and the Slash 8 Gen 6 will be an absolute rocket ship on the toughest of trails.

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