Specialized Stumpjumper 15 Expert long-term review – initial report

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I was fortunate enough to ride the new Specialized Stumpjumper 15 on the launch last summer and really fell for it, hook, line and sinker.

It climbed well, and felt agile and fun, but could hold its own when things got rowdy.

As someone who generally rides an enduro bike in my own time, making this switch to a lighter-weight trail bike with less travel felt like a bit of a gamble.

But maybe this is the type of bike I really should be riding. A real all-rounder that is happy ticking off the miles but not afraid to get a little rowdy when necessary.

In my fortunate position, I get to ride a lot of bikes each year, but with my past firmly rooted in downhill, I’ve opted to ride longer-travel enduro bikes for the most part.

With a carbon frame, Fox Performance Elite fork and shock, SRAM Maven brakes and the latest GX Eagle AXS Transmission gearing, there’s a lot to like about the Expert version of the Stumpjumper 15.

But what’s it like to live with?

Specialized Stumpjumper 15 Expert frame, suspension and specifications

The Stumpjumper 15 frame is made from Specialized’s 11m carbon fibre and built around 29in wheels.

One thing that’s already caused me an issue is the lack of cable routing through the frame for a mechanical, rather than wireless, rear derailleur.

This isn’t an issue on the alloy frame, though.

There’s ample frame storage thanks to the redesigned SWAT compartment inside the down tube, where you can easily stow essentials.

The real ace in the Stumpyjumper 15’s pack is the new Fox Float shock, which uses Specialized’s GENIE technology to control the 145mm of rear-wheel travel.

This cleverly creates a dual air spring, thanks to the two positive (and one negative) air chambers.

Both chambers can be tuned using volume spacers to adjust their feel. While the larger, outer sleeve chamber dictates how the first 70 per cent of travel feels, the smaller chamber at the shock's eyelet manages the final 30 per cent.

The transition between the two positive air chambers happens when the GENIE band slides up and closes off ports to the outer sleeve, reducing overall air volume to create a controlled ramp up at the end of the shock's stroke.

Specialized created the shock using existing Fox shock parts, and the only thing that’s truly unique is the volume spacers. These are shipped with the bike.

That means having your shock serviced or working on it yourself (if you’ve got the kit and know-how) should be nice and straightforward.

Despite testing multiple suspension systems, Specialized says it stuck with the proven four-bar Horst-link design because it does everything that’s required really well.

Specialized Stumpjumper 15 Expert geometry

Specialized sells the Stumpjumper 15 Expert with 29in wheels bolted in, but offers an aftermarket link to maintain the geometry should you wish to switch to a smaller rear wheel – something I certainly intend to do.

There’s plenty of adjustment of offer here, so it’s easy to tweak the angles to your heart's content. There are three head angles to choose from (thanks to angled headset cups), with a 1 degree difference between them.

In the middle setting, mine measured close to the stated 64.5 degrees, with a seat tube angle around the 78-degree mark, with the saddle set to my preferred height.

A flip chip in the Horst-link pivot tweaks the chainstay length and bottom bracket height by 6mm and 7mm respectively.

My size S3 has a reach of 450mm, chainstay length of 435mm and bottom bracket height of 335mm.

Specialized Stumpjumper 15 Expert specifications

Alongside the Fox Float Performance Elite GENIE shock, there’s a Fox 36 Performance Elite fork, complete with GRIP X2 damper and 150mm of travel.

A big plus for me is the SRAM Maven Silver brakes, paired with 200mm rotors at the front and rear.

And it’s great to have GX Eagle AXS Transmission gearing here, too.

Specialized provides a host of their own kit, including the bar, stem and saddle, although the grips are from Deity and a real highlight. I won't be changing them anytime soon.

Something I will be switching, though, is the tyres. While the Butcher and Eliminator make a great combination, the lighter Grid Trail casings used here hold the Stumpjumper 15 back because you need to add pressure to ensure they hold their shape when ripping a turn.

It’s great that they’re really fast-rolling and traction is decent, but I want something a little sturdier.

Specifications

• Sizes (tested*): S1, S2, S3*, S4, S5, S6
• Frame: FACT 11m carbon
• Fork: Fox Float 36 Performance Elite
• Shock: Fox Float Performance Elite
• Crankset: SRAM GX Eagle, 32T ring
• Bottom bracket: SRAM DUB, BSA 73mm wide, threaded
• Cassette: SRAM GX Eagle Transmission, 12spd, 10-52t
• Chain: SRAM GX Eagle Transmission Flattop
• Derailleurs: SRAM GX Eagle Transmission
• Shifters: SRAM AXS POD controller
• Wheelset: Roval Traverse, hookless alloy
• Tyres: Butcher, Grid Trail casing, Gripton T9 compound, 2Bliss Ready (F) / Eliminator, Grid Trail casing, Gripton T7 compound, 2Bliss Ready (R)
• Stem: Alloy Trail, 35mm bar bore
• Bar: Specialized, 6000 series alloy
• Grips: Deity Lockjaw
• Saddle: Bridge Comp, Hollow Cr-mo rails
• Seatpost: PNW Loam dropper
• Brakes: SRAM Maven Bronze / HS2 rotors 200mm

Why did I choose this bike?

Hot off the back of the press camp in Canada, where we rode some pretty wild terrain, I was really impressed by what this little trail bike could handle.

It made me re-think my usual choices. Maybe I shouldn’t always be on an enduro bike with travel figures close enough to make it a downhill bike. Maybe this is the type of bike I should be riding.

I was a little nervous at first, thinking that the lack of travel and burly componentry might hold me back, but now I’m riding the Stumpjumper 15, I know I needn’t have worried.

Specialized Stumpjumper 15 Expert initial setup

Having ridden two Stumpjumpers already, setup was a breeze.

The big thing here is the shock. I settled on 30 per cent sag, with a single volume spacer in the outer air sleeve and the 0.2in spacer in the shock's eyelet.

I’d done a lot of experimentation with setup previously when I tested the Pro and S-Works versions so knew what I liked, making things much quicker from the off.

The fork was set to my preference, including winding off all damping dials so they were fully open. I’ve found the current range of Fox forks to be quite heavily damped and, with my 68kg weight, I need the dials fully backed off to ensure they move fast enough.

Specialized Stumpjumper 15 Expert ride impressions

While I haven't spent all that much time on the Expert version of the bike seen here, I’ve had plenty of rides on the S-Works and Pro versions and it’s safe to say this shock works.

After testing out almost every spacer combo going, I ended up back with the stock setup, with only one spacer in the sleeve and the 0.2in spacer in the eyelet.

In this configuration, the green machine feels decently supple, but I can still drive my weight down through the pedals and pump when I need to gain speed.

Thankfully, there’s ample ramp-up for those nasty heavy landings when things do go a little wrong.

Elsewhere, the 150mm-travel Fox 36 fork doesn't feel as forgiving as it could. I’m not quite sure what’s going on with these Fox forks at present.

I’ve had some good ones, and some less good ones over the last few months, which is a shame because I know the damper is really good in a properly serviced fork. Hopefully, this fork will loosen up over time.

Otherwise, I'll need to make a trip to see the guys at Sprung Suspension.

While the green carbon frame might be quite bright for some, I’m into it. Cleaning it takes a little more care and it's proving hard to get spotless, but it certainly stands out.

I’m also a fan of the angles. I’ve gone for the size S3 and its proportions fit me incredibly well. I’m fully intending on playing around with the geometry adjustment, though, and have ordered a link to switch to a smaller wheel size at the rear, too.

I’ve already had quite a few tyre-to-backside incidents and I’m keen to put an end to them.

I like the fact that Specialized specs the monster Maven Bronze brakes – something not all trail bikes can boast.

I will swap the tyres for something tougher for sure, even if it does add a bit of weight.

Having something more robust and less delicate will open trails up and I’ll be able to ride with a little less worry when thudding down anything remotely rocky.

Even without these small changes, I’m stoked every time I sling a leg over the green machine. It feels easy to ride and incredibly capable. It’s going to be a great year aboard the Stumpjumper 15 Expert.

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