2025 Trek Slash+ Review | Subtle motor, outrageous suspension

2025 Trek Slash+

Trek Bikes

https://www.trekbikes.com

From $11,499 AUD ($17,999 AUD as tested)

20.9kg

- Stupendously plush, traction-rich suspension- Incredible composure at speed- Quiet & smooth motor performance- TQ battery offers low weight with plentiful range- Can also be ridden without the battery

- Heavy for a 'lightweight' e-MTB- TQ motor will be too subtle for some riders- Noisy chainslap

The Trek Slash+ burst onto the scene earlier this year as the longest travel electric mountain bike the US brand has ever produced. Building on the success of the lightweight Fuel EXe that launched back in 2022, the Slash+ features the same compact TQ HPR50 motor. It then pumps things up with a new, larger 580Wh battery while also carrying over the distinctive high pivot suspension design from the non-motorised Slash. The result is an intriguing e-MTB that combines big travel with a small motor.

Having reviewed the Fuel EXe, the Rail and the regular Slash, our expectations were pretty high when the Slash+ turned up for testing. How would it compare to its siblings, and what kind of riding experience does this burly e-MTB deliver?

Watch our video review of the Trek Slash+ here:

Just like its non-motorised counterpart, the Trek Slash+ features 170mm of travel front and rear. The OCLV carbon frame is built specifically around a mullet wheel setup, with the exception being the Small size that rolls on dual 27.5in wheels.

The ‘+’ part of the name refers to the electrified assistance, which in this case is delivered by the German-manufactured TQ HPR50 motor. Weighing less than 2kg, this tiny drive unit pumps out up to 50Nm of toque and 300W of peak power. It’s easily one of the most natural-feeling motors out there, and in our experience, it’s the quietest too. See our separate TQ HPR50 review for everything you need to know.

The compact motor frees up the necessary real estate for the high pivot suspension design, which is claimed to feature identical kinematics to the regular Slash. Typically e-MTBs will require a different shock orientation and suspension linkage to fit around bulky motors and batteries, but that’s not the case here.

Indeed the Slash+ manages to hide the ‘e’ part quite well, incorporating a discreet display that sits flush with the top tube and a two-button controller next to the left-hand grip. The slim 580Wh battery is bolted inside the downtube, though it can be easily removed for charging separately, something that isn’t possible with many other lightweight e-MTBs. You can also ride without it, which I’ll discuss in more detail shortly.

As with the kinematics, geometry is largely identical between the Trek Slash+ and the regular Slash. The biggest difference is the omission of the M/L size, which means the Slash+ is only available in four frame sizes.

Otherwise it gets the same 63.4° head angle with the neutral headset cups fitted. You can purchase offset headset cups aftermarket, which allow you to slacken or steepen the head angle by a full degree.

Depending on the frame size, Trek tailors both the seat angle (76.7-77.6°) and rear centre length (434-445mm). And while geometry adjustment is limited to the headset cups, the Slash+ does incorporate a flip chip at the lower shock mount. This provides you with linear and progressive leverage rate settings, with the latter being particularly well suited to a coil shock. The frame is also rated for up to a 190mm travel fork for those who want to beef up the front end.

There are just two complete bike options in the 2025 Trek Slash+ lineup. Prices start at $11,499 AUD for the 9.7 model that utilises exactly the same OCLV carbon frame, TQ motor and 580Wh battery.

Our test bike is the top-end Slash+ 9.9, which comes with a not-insignificant price tag of $17,999 AUD. It’s worth pointing out that it has an identical retail price and spec as the non-motorised Slash 9.9 X0 AXS T-Type. So if it’s any justification, you’re effectively getting the motor and battery for free!

At 174cm tall I’ve been riding a Medium size Trek Slash+. The 449mm reach and 631mm stack have suited me well, and the 77.5° effective seat tube angle puts you in a fairly upright and central position.

Unlike some other Trek bikes we’ve tested lately that come with one-piece Bontrager RSL cockpits, the Slash+ sticks to a conventional handlebar and stem that allows you to adjust the bar roll or swap out the stem if needed. It also employs a standard headset with good ol’ fashion round spacers that makes it easy to change the bar height.

I don’t love Bontrager’s squishy but still firm grips, though the snub-nose Verse saddle has proven to be plenty comfortable, and the long rails provide a heap of adjustment for tweaking the effective seat angle.

While the 170mm dropper post is fine for me, it’s a shame that taller riders on the Large and XL have to make do with the same length post. Of course this is primarily RockShox’ problem, since the Reverb AXS maxes out at 170mm. Here’s hoping a longer travel Reverb AXS is in the works.

The Trek Suspension Calculator offers a useful place to start when setting up Slash+. To hit the recommended shock sag of 30% I needed 175psi to support my 68kg riding weight. I set rebound damping on the faster side (14/18 clicks) and positioned both the high and low-speed compression dials in their neutral positions.

The Vivid Ultimate also encompasses a Hydraulic Bottom Out adjustment that allows you to increase the ramp-up in the final 20% of the stroke. I didn’t need much more than 1-2 clicks as the suspension on the Slash+ already offers plenty of support. For the same reason I left the shock’s flip chip in the less progressive setting throughout testing.

While the suspension worked beautifully for me, it is great to have the option to increase progression and add more clicks of HBO for those who are jumping higher and landing heavier than I am.

I also went with Trek’s recommendations for the Zeb Ultimate, but found it to be a little too firm at 59psi. I ended up dropping the pressure down to 54psi over the first few rides, which made it considerably smoother and easier to use the final third of the travel. Again, I set the rebound on the faster side (12/20 clicks) and ran the compression dials in the neutral position.

Confirmed weight for our Trek Slash+ test bike is 20.9kg without pedals, which is quite portly for an e-MTB fitted with a TQ motor. It’s more than 2kg heavier than the Fuel EXe we’ve tested previously, though of course the Slash+ features 20-30mm of extra travel, a more complex suspension design and significantly burlier components.

It also comes with a larger 580Wh battery, which turns out is actually very lightweight for its size at 2,710g (confirmed). That’s because it uses higher energy density cells compared to the existing 360Wh battery you’ll find in Fuel EXe, resulting in just an 820g weight penalty.

The rest of the build is pretty solid all-round, including the big Zeb fork and Vivid shock. Even the Bontrager Line Pro wheels are on the stocky side despite the carbon rims, weighing in at over 2kg for the wheelset including the TLR rim strips and valves.

The tyre spec is aggressive without being super heavy duty, with confirmed weights of 1,150g for the SE6 and 1,037g for the SE5. That puts them on par with equivalent Maxxis EXO+ tyres, which likely won’t be burly enough for riders who are pushing the limits on really chunky terrain. To help shield the carbon rims and avoid making use of Bontrager’s 2-year crash replacement scheme, I fitted a CushCore Pro insert in the rear wheel. Tyre pressures ranged from 20-22psi up front and 23-25psi out back.

As Dan encountered on the regular Slash when he reviewed it earlier this year, it’s the suspension performance of the Trek Slash+ that stands out as one of its best attributes.

The rear end gobbles up everything in its path, devouring the chunkiest of rocks and the girthiest of roots. It might not have the highest pivot out there, but there’s enough rearward movement to allow the wheel to get out of the way quickly and to help maintain momentum when you’re skipping across sharper edges. Along with the carefully managed chain and neutral anti-squat levels, the Slash+ affords a smooth and somewhat relaxed ride quality when the speeds are high and the trail gets rowdy.

Of course the geometry puts you in a great stance on the descents, though it’s the plush and reactive suspension that takes stability to the next level. Even under heavy panic-braking it remains calm, allowing the rear end to generate gobs of traction. It does a lot to elevate the confidence levels, to the point where I found myself ticking off several trail features that I’d baulked at over the past couple of years.

Much of the praise can be attributed to the excellent RockShox Zeb and Vivid, an awesome combo that delivers sensitivity and control by the bucketload. Both are intuitive to set up with simple but meaningful adjustments. I found adding a bit of low-speed compression to the shock helped to lift the ride height and provide a stronger platform for pushing into when hitting doubles. For those same trails, an extra click or two of the fork’s high-speed compression dial meant it could absorb more impact energy without me having to reach for more Bottomless Tokens.

Given the Trek Slash+ shares the same suspension design as the non-motorised version, its outrageous traction and big-hit capability weren’t exactly a surprise. What did surprise, is how just much fun it is to ride on less technical terrain.

No doubt the mid-high pivot orientation comes into play here. Although the rear centre lengthens as the shock cycles through its travel, it isn’t as dramatic as some other high pivot bikes, so there’s less of that stuck-down sensation. Combined with the mullet setup and relatively lightweight battery, the Slash+ is actually quite responsive on flowier trails. It flies off jumps intuitively, and there’s a heap of grip on offer from the aggressive Bontrager SE6/5 combo.

The static 352mm BB height might sound tall, but it actually sits low to the ground once suspension sag is taken into account. Along with the supportive suspension, it helps to keep the bike planted when torpedoing into high-speed berms. Providing you’re willing to push the inside grip down and make use of the sticky tyres, the Slash+ snakes its way through singletrack chicanes with very little fuss.

The TQ motor also contributes to the overall liveliness, adding a good amount of zip across undulating singletrack. The assistance is smooth and subtle, so you never feel like you’re a passenger. In fact, it’s easy to forget there’s even a motor there, which I suspect is what a lot of mountain bikers are looking for in an e-MTB.

Although the TQ HPR50 does well given its diminutive size, it lacks some punch on steeper tech climbs compared to the equivalent Fazua Ride 60 and Bosch SX motors. It isn’t hugely powerful, and that means you’ll have to put in a decent amount of effort to maintain your speed when the trail kicks up.

Personally speaking, I really like this motor. It’s quiet and natural-feeling, and its compact form means Trek didn’t need to compromise when it came to the high pivot suspension layout. I’ve also found it to provide sufficient assistance to allow me to climb significantly faster compared to a non-motorised enduro bike. Sure, the Slash+ isn’t as planted on steeper gradients compared to a full 29er like the Scott Voltage, but it still offers plenty of rear wheel grip and stable pedalling performance for negotiating technical ascents.

However, I say all of this as a relatively light and fit rider. Heavier folks will be more likely to take issue with the subtle assistance. On that note, I do think there’s something to be said for matching rider weight with a motor’s output, but perhaps that’s a discussion for a different day. Needless to say, if you’re the sort of person who’s looking to get up the mountain as quickly and with as little effort as possible, this motor isn’t for you. The Rail, with its full-powered Bosch CX motor, will be a more suitable choice.

This does present a bit of a conundrum because at nearly 21kg, the Trek Slash+ is heavy for a bike that sits in the ‘lightweight’ category. It certainly rides lighter than that figure suggests, which can partly be attributed to the class-leading energy density of the TQ battery that keeps the centre of mass relatively low. Still, it does require more muscling around at slower speeds and when things get particularly tight and twisty. On the sorts of modern machine-built flow trails that are popping up all around Australia, the shorter travel Fuel EXe is likely to be the better option. It’s lighter, offers sharper handling, and is just that little bit easier to place on the trail.

There are a lot of riders out there who have ended up over-forking and up-stroking their Fuel EXe, and it’s perhaps those riders that the Slash+ is going to appeal to the most. The suspension is significantly plusher, offering more grip and big-hit composure than the Fuel EXe. The Slash+ comes out of the box ready to shred, and the fact that you can add a coil shock and extend the fork to 190mm makes it especially attractive for those who are going to be spending a lot of time at the bike park.

On that note, I can confirm that it is possible to ride the Slash+ without the battery. After removing it from the downtube, you’ll find a small threaded nut that’s tucked away inside the motor skid plate that can be used in place of the battery thread. I then zip-tied the main plug to stop it from bouncing around inside the downtube, and replaced the wired-in AXS battery for a regular version.

This dropped the weight of the Slash+ down to nearly 18kg, and in my experience it makes a significant difference to the handling on fast and flowy trails. The TQ motor runs pretty much drag-free, so you could potentially ride it in this configuration alongside pals with regular enduro bikes. For a weekend of shuttling or using the chairlift at a bike park, it’s a great feature.

The only other issue I encountered throughout testing was a decent amount of rattling when bouncing down rough descents. Dan had the same problem with the regular Slash, and in both cases it turned out to be from chain slap.

Although Trek’s thick chainstay protector offers plenty of coverage, it is quite firm. I wrapped it with a rubber inner tube, which instantly eliminated most of the noise. There’s still some contact with the mudguard and upper chainguard when the chain bounces around, so lining those with rubber or velcro could help quieten things down further.

Now I don’t think I’m being overly critical when I say that riders shouldn’t have to be making such modifications on a bike that costs this amount of money. At least it was cheap and easy for me to do, but Trek really should have this dialled.

Thankfully I encountered zero issues with chain derailment, which was a point of concern with the non-motorised Slash when it launched last year. The Slash+ incorporates a new fully enclosed lower pulley along with a redesigned lower guide that beefs up the chainring protection while sharing the same mounting bolts as the motor. Everything ran snug and secure throughout testing, though as we’ve mentioned with other idler-equipped bikes, keeping the chain clean and well-lubricated is essential for staying on top of general drivetrain noise. I’ve been using Maxima Chain Guard, which is a thicker wet-condition lubricant that seems to keep things running quieter for longer.

Most of my rides aboard the Trek Slash+ were with the TQ motor set to its High assist setting. Distances varied from 44-55km, with 1,200-1,500m of elevation gain.

Of course using the Mid and Eco modes will help you to eke out more range from the 580Wh battery, and you can also make use of the TQ app to tune the motor’s power output should you wish to tailor the assistance further.

To benchmark the Slash+ against the competition, I also put it through our standardised range test. With the motor set to its most powerful setting, I pedalled up the same road climb as usual, before riding a singletrack descent back down to see how many laps I could shuttle before the battery went flat.

Here’s how the Slash+ stacked up against the rest;

Close to 2,000m of elevation gain is impressive, especially when you consider that was close to the Scott Patron, which has a much larger 750Wh battery.

It is worth noting that the compact TQ motor doesn’t exactly zoom you uphill, with my average climbing speed hovering around 14km/h. That’s quite a bit slower than the Fazua Ride 60 motor in the Focus JAM² SL (16km/h) and the Bosch SX motor in the Norco Fluid VLT (18km/h), which is something to consider depending on what you want out of an e-MTB motor.

For the asking price of $17,999 AUD, the Trek Slash+ 9.9 X0 AXS T-Type is a serious amount of cash. Though as mentioned before, it weirdly looks like great value alongside the regular Slash that sells for the same price with an identical spec. Honestly, why wouldn’t you want the motor and battery?

As for other e-MTBs with comparable spec, you could spend less on the Amflow PL Carbon Pro ($13,999 AUD) and the Merida eOne-Sixty 10K ($15,999 AUD), or a similar amount on the new Santa Cruz Vala X0 AXS ($17,499 AUD). Then again, you could easily spend more on the Pivot Shuttle AM Pro X0 ($19,999 AUD) or a Specialized S-Works Kenevo SL ($21,500 AUD).

In terms of the components on our Slash+ test bike, I have few complaints. SRAM’s X0 Transmission has been rock-solid, and it’s great to see Trek spec’ing nice and short 160mm crank arms. The new AXS Rocker Paddles are a nice touch too, providing a larger surface area to engage the gears and dropper post. Perhaps I’m nitpicking here, but I’d love it if you could use the left side to control the motor’s assist levels and eliminate the TQ controller and wire from the cockpit.

The Maven brakes continue to impress with their immense power, and it seems that the more time we spend on these, the more we’ve been liking them. Aside from some spoke pinging the Bontrager Line Pro wheelset has shrugged off a tonne of abuse, and it’s great to have that two-year crash replacement for some added peace of mind.

Despite not providing the best experience in the past, I’ve actually been really impressed with the Bontrager SE6 and SE5 tyres. My suspicion that something was different proved to be correct, as it turns out Bontrager has made a rolling change with these tyres. The casing and tread design are the same, but they get a new dual compound structure with a softer 42a rubber for the upper layer. This provides much stickier performance and better damping, which puts them pretty close to a Maxxis 3C MaxxGrip tyre.

I recently tested the Merida eOne-Sixty, which might seem like a slightly unusual comparison to the Trek Slash+. The eOne-Sixty isn’t meant to be a lightweight e-MTB after all, as it’s powered by a conventional Shimano EP801 motor and a 600Wh battery.

That said, both bikes feature the same amount of travel and a mullet setup. Along with a similarly burly build, the eOne-Sixty 10K isn’t that much heavier at 22.5kg. It is cheaper at $15,999 AUD despite coming with a more premium XX Transmission and DT Swiss carbon wheels.

I was also impressed with the eOne-Sixty’s all-round handling, which proved to be a bit more playful overall. The supportive suspension gives it good response when pumping through flowy trails, and the not-uber-slack geometry means it carves up turns intuitively for such a big travel e-MTB.

The 85Nm Shimano EP801 motor is also considerably more powerful, allowing you to climb faster and with less effort. It seems to be really efficient too, with the eOne-Sixty actually beating the Slash+ in the range test despite having a similar size battery and a much faster climbing speed. I think if you were buying an e-MTB and motor power was one of your top priorities, the eOne-Sixty would be hard to look past. It offers great value, especially in the alloy versions that can be had for well under $10K.

When it comes to handling and suspension performance however, the Slash+ is just really bloody good. It’s plusher overall, and the high pivot platform provides a noticeable boost to high speed stability. The end result is an incredibly confidence-inspiring ride that will suit folks looking for maximum capability.

The Trek Slash+ sits in a slightly unusual space. It’s heavy for a lightweight e-MTB, and the TQ motor looks dainty compared to the equivalent Fazua Ride 60 and Bosch SX drive units. That makes it a less appealing option for those folks who are looking to combine maximum power with maximum travel.

The thing about the TQ motor though is that it’s more than just numbers on paper. There’s a lot to be said for its smooth and whisper-quiet performance, and the compact shape is what makes the high pivot suspension design a possibility in the first place. With the Slash+ sharing the same kinematics and similar geometry to the regular Slash, its performance on properly rough and technical singletrack is outstanding.

It’s also capable of racking up a serious amount of range from the 580Wh battery, and the fact that you can ride without it is a great feature for lift-assisted riding.

The Slash+ 9.9 X0 AXS T-Type certainly isn’t a cheap bike, though given Trek sells equivalent Slash models for the same price with identical spec, it’s a bit of a no-brainer as to which to go for. That’s especially the case for folks who are looking for a more discreet level of assistance, and place suspension performance and handling above all-else.

Bendigo, Victoria

175cm