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

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

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.

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.