Bikes Blog
Specialised Stumpjumper 15 Professional Evaluate: A Genie in an Air Spring and Adjustable Versatility
Jul
The Specialised Stumpjumper should be probably the most iconic path bikes in MTB historical past. The primary hardtail mannequin was launched 43 years in the past, and Specialised has simply introduced the fifteenth model of the complete suspension Stumpjumper. I’ve been using the Stumpjumper 15 Professional for a month, and it rides like a motorbike that’s benefitted from years and years of refinement.
With 145mm of rear journey, 29” wheels (as examined), and adjustable geometry the Stumpjumper is a do-anything, go-anywhere path bike. The brand new Genie rear shock is the icing on the cake, enabling this mid-travel bike to deal with massive impacts and tough terrain extraordinarily effectively. I had the prospect to journey the Stumpy in two very totally different path networks, and it excelled in each for various causes.
Specialised Stumpjumper 15 – Key Specs:
Make sure you try my launch publish for full particulars on the brand new Stumpjumper lineup, however right here’s a fast rundown of the important thing specs and options.
The Stumpjumper 15’s entrance and rear triangles are produced from Specialised’s Fact11m carbon fiber. The bike gives 145mm rear journey pushed by an FSR linkage. Most fashions run 150mm forks (besides the smallest S1 frames, which have 140mm forks, and the Ohlins Coil mannequin which has a 160mm fork).
Specialised shares MX wheels on the smaller body sizes (S1 and S2), and 29” wheels on all bigger frames. The bigger sizes can run a 27.5” rear wheel, when you swap out the hyperlink for an aftermarket model that maintains the bike’s geometry and suspension kinematics.
Some key updates from the final Stumpy are the brand new angle-adjustable headset, the dearth of a Sidearm assist on the body, and wi-fi drivetrain-specific cable routing. That’s proper – there isn’t a routing for a derailleur cable on this body! Specialised determined to drop the sidearm assist in favor of a bolstered hyperlink and a cleaner design.
Lastly, the brand new Genie rear shock is a key part of the Stumpy 15’s versatility. Specialised developed this shock alongside the brand new Stumpjumper, and it gives a novel double air chamber system that reduces its air quantity at 70% stroke. This creates a pointy ramp-up impact at end-stroke, significantly lowering harsh bottom-outs on tough terrain or massive landings. The primary 70% of the stroke is independently tuneable so you possibly can select between the softest, most delicate suspension attainable or a extra supportive, poppy journey.
I used to be very comfortable to see the dimensions S3 Stumpjumper 15 Professional weighing in it simply 31.72lbs (with pedals)!
Match and Geometry:
The Stumpjumper is obtainable in six body sizes, following Specialised’s S sizing scheme. At 5”10”, I discover myself in the midst of the S3 and S4 sizes, however I opted to check an S3. At 450mm attain, this body is shorter than lots of present ‘medium’ bikes, however at 475mm the S4 could be one of many longest bikes I’ve ridden. Given the Stumpy is a path bike and never a long-travel enduro, I loved the agility and playfulness of the S3 body.
Specialised saved the S3 body’s chainstays at a middle-of-the-road 435mm, which permits for whippy cornering and a playful journey. Nevertheless, the adjustable steering angle and low BB top choices can enhance the bike’s stability and functionality on steep descents.
I’ve fairly lengthy legs so standover top is normally not a priority for me. The Stumpy isn’t notably low at 745mm however I had ample clearance over it. Specialised didn’t go tremendous low with stack top both, and I saved 4 spacers below the stem so I loved a fairly comfy using place on the S3 body. Given this bike is right for lengthy days rambling across the trails, I selected to not get too aggressive with the entrance finish.
*Please be aware the geo chart reveals solely the impartial/excessive BB figures. The swappable headset cups enable for a +/- 1° steering angle adjustment, and dropping the BB with the chainstay flip-chip lowers it by 7mm and slacks out the bike one other 0.5°.
I rode the Stumpy in two positions throughout my check; impartial/excessive BB, and slack/low BB. I began off in impartial/excessive place at Specialised’s launch occasion in Cowichan Bay, B.C., and later swapped to the slackest and lowest place whereas using my a lot rougher native trails in Pemberton, B.C.
Cowichan Bay Experience Notes: Geometry
The paths we rode in Cowichan Bay have been pretty buff, quick working movement runs with deep, swoopy berms and a few small jumps. There are just a few bumpy rooty sections, however nothing too technical or free. The climbs have been a mixture of hearth street and singletrack trails, with some steeper bursts however principally low grades.
Straight away I might inform the Stumpjumper is a good choice for a do-everything bike. Its 145/150mm journey is right, and the bike rides just like the midway level between an enduro and a brief journey path bike. Even within the impartial/excessive place, it gives a surprisingly steady journey, but the Stumpy additionally stays agile and playful. The impartial steering angle was nice for these trails, it’s slack sufficient for assured descending however nonetheless navigates uphill switchbacks properly. There are berms galore in Cowichan Bay and the Stumpy’s 435mm rear finish railed by way of them. It’s additionally fairly simple to wheelie this bike over whoops, and the short-ish body made it a pleasure to toss round on the jumps.
Suspension:
With the rear shock in Agency mode, the Stumpy is an aggressive climber that pedals very effectively. On any terrain the Stumpy will use about 50% journey below pedaling forces and low-speed wheel impacts with the shock firmed up. The Stumpjumper can be a really cheap bike to climb in open mode, because it pedals effectively by itself with little noticeable bob. Whereas it does enable the bike to dip and wallow below your physique weight extra, Open mode might optimize grip on technical climbs with little lack of effectivity.
Utilizing the shock’s Agency mode is far more efficient at conserving the bike using excessive than including 4 spacers (extra on spacers beneath) and climbing in open mode. When you’re fascinated with utilizing the quantity spacers to make sure stable climbing, I’d suggest utilizing the shock swap as a substitute. That approach you possibly can preserve the suspension arrange for descents and easily flip the swap for optimum climbing prowess.
The Stumpjumper’s linkage itself has a supportive mid-stroke. The bike pumps by way of rollers very well and doesn’t wallow into its journey in swoopy berms with massive G-outs. What’s nice is that you would be able to fine-tune the extent of assist with the Genie shock’s quantity spacers.
Genie Rear Shock Tuning:
I spent the primary day in Cowichan Bay using with one spacer within the Genie rear shock. Straight away I might inform this tune was working for me, as I obtained near full journey on each lap. Bump absorption was impressively easy for the Stumpy’s 145mm journey, but I by no means felt any harsh bottom-outs on our first journey day.
At this level I ought to point out there isn’t a noticeable really feel when the shock’s Genie Band slides up and closes its outer sleeve ports for the final 30% of journey… the transition goes fully unnoticed. The oldsters at Specialised defined that due to how air compresses, the Genie shock received’t produce a harsh, abrupt feeling when the outer chamber will get reduce off. It merely continues to compress persistently regardless of the speedy discount of air quantity inside.
On day two I attempted all 4 spacers within the shock. The bike did really feel extra supportive total and stiffer by way of corners. There was no enormous loss in small/medium bump absorption however there was a noticeable distinction; using over roots felt a bit extra abrupt and obvious on this setting.
I used to be fairly shocked this setup wasn’t approach too stiff for me, as a light-weight man at simply 130lbs (following some current weight reduction… lengthy story!). The spacers are far more of a fine-tuning instrument than I anticipated, however they positively supply a noticeable vary of adjustment. Do not forget that the Genie shock makes use of eyelet spacers to tune its bottom-out resistance, so including/eradicating outer sleeve spacers adjustments the Stumpy’s preliminary/mid-stroke behaviour with out altering its end-stroke progressivity.
I did my remaining laps with no spacers within the Genie shock, which supplied a noticeably softer journey than the 4 spacers, however not as excessive a distinction between the 2 as anticipated. There was a particular enchancment in small bump absorption, and an clearly softer really feel when popping off roots/rocks. The bike dipped into its journey extra between rollers and in corners, and I did hit backside out just a few instances on this configuration.
Pemberton Rides:
I introduced the Stumpjumper residence from Cowichan Bay to my native trails in Pemberton, B.C., that are so much rougher and steeper. This was an excellent alternative to see how well-rounded the Stumpy might be, and it proved itself! Given the tough terrain, I did bump up the shock to 135psi, and began with no spacers within the Genie’s outer air chamber.
As for geometry, I observed whereas climbing the shorter S3 body permits for good physique motion over the bike. When it’s essential to heave your self proper up over the pinnacle tube, it’s simple to take action. Whenever you’re struggling and yanking the bike round tight corners or up technical obstacles throughout a climb, the less-than-enduro size of this bike is considerable. The rear finish is simply lengthy sufficient to carry traction effectively on steeper uphills, and with its cheap weight the Stumpjumper 15 Professional is a pleasure of a motorbike to climb.
For the previous couple of check rides, I switched the Stumpjumper to its slackest steering angle and low BB setting. I instantly went to the steepest descent in my space, and the Stumpy dealt with it like a champ. 63° is the slackest steering angle I’ve ridden on any bike, and it provides the Stumpy enduro-grade functionality on actually steep terrain. On the climbs, the entrance wheel begins to really feel a bit floppy with the bike absolutely slacked out, however I discovered this minor lack of agility simple to tolerate.
Even on Pemberton’s bumpier climbs, the shock’s Agency mode retains you to 50% journey. The bike nonetheless hugs bumps properly and gives ample traction, however doesn’t take in bumps generously… the rear finish lifts over obstacles and resists diving into holes between roots/rocks.
Climbing in Open mode produces a bit extra bobbing/wallowing. Pedalling continues to be very effectively supported however I observed extra motion from the rear finish when rolling by way of dips within the path whereas seated. The rear wheel strikes noticeably extra in Open mode, so it gives a extra comfy climb. The trade-off is a few lack of momentum on bumpy sections, because the rear wheel dips into holes extra simply. I hit about 80% journey after a protracted technical climb with just a few small downhill sections.
I used to be happy to search out I didn’t expertise as many pedal strikes as anticipated with the BB in Low setting. I did knock just a few rocks and roots, however didn’t must be as cautious as I anticipated. Even in its Excessive place, the Stumpy is a low-slung bike, however dropping to Low will increase that steady journey really feel only a bit extra.
As for descending rougher trails, the Stumpy dealt with every thing very well. My first descent was down a quick, rocky run and I got here away impressed with how easily the bike ate it up. At this level I double-checked the underside out level on the shock and confirmed that the Genie was ramping up properly and conserving me simply above full journey on lots of laps. After hitting 99% journey on Cowichan Bay’s smoother trails, I used to be a bit anxious the bike is likely to be too smooth for Pemberton however with a slight bump in air strain it proved completely positive.
The Stumpjumper took care of chattery small and medium-sized bumps in very easy trend, leaving me fairly impressed with its total bump-handling skill.
Specialised had a sure stiffness in thoughts once they designed the brand new Stumpy body. Whereas they did keep some flex and compliance, at my weight I discovered the Stumpjumper felt fairly stable and held traces by way of the tough stuff simply.
Genie Shock Tuning Continued:
I took a day to experiment with the Genie’s outer chamber quantity spacers once more on my tough native trails. On the bumpier climbs I did really feel a little bit of a distinction in suspension conduct, even with the shock in Agency mode. With 4 spacers put in the bike resists diving fairly strongly, particularly when seated and rolling by way of dips. The rear finish feels a bit stiffer when absorbing bumps, however journey use remained constant at 50%.
When climbing in Open mode with 4 spacers, the spacers don’t produce a giant increase in pedaling effectivity or scale back journey utilization. I nonetheless hit almost 80% journey climbing in Open mode, in order talked about earlier the shock’s swap has far more impact on climbing effectivity than the outer air chamber spacers.
Descending with 4 spacers supplied noticeably much less easy bump absorption and fewer preliminary sensitivity, however nice pop off jumps. With the spacers within the bike carries velocity effectively over rooty sections, so if velocity is your precedence (or for race day?) you would possibly wish to add spacers… however this comes on the expense of journey consolation and small/medium bump gobbling functionality.
Working one quantity spacer appears to be the candy spot for me on tough terrain like Pemberton. In Cowichan Bay I would run two spacers however not when bump absorption is the precedence! With one spacer the Stumpjumper nonetheless eagerly eats up small and medium bumps, gives an impressively easy journey for its 145mms of journey, and gives the energetic journey of a brief journey path bike.
Body Storage and Elements:
The SWAT 4.0 body storage gives sufficient area to hold the same old journey necessities. I used to be capable of carry a big c02 canister, inflator head, plug instrument, spare plugs, a spare battery for the AXS shift pod, and a multi instrument with room to spare. Specialised provides a bag to carry instruments within the body, which works however I’ve discovered instrument rolls do a greater job of stopping issues from rattling round within the bike. I merely wrap my c02 canister in a rag, and it retains issues quiet. I used to be fairly comfortable to search out the bottle cage might maintain a big water bottle within the S3 body with ample area to entry it simply.
Take a look at the Specialised web site for full construct specs, however listed below are just a few fast notes on elements: Fox’s 36 Manufacturing unit fork supplied nice efficiency, and was dialed in properly with only a fundamental setup. The included fender is a pleasant contact.
The SRAM Maven Silver brakes on 200mm rotors supply tons of energy and aren’t too bitey. I’ve discovered the chew level on Maven brakes tends to maneuver round a bit (on the Ultimates and Silvers up to now…) however with their good modulation it’s not important sufficient to threaten my management over the bike.
SRAM’s X0 AXS shifting has been flawless, which is sweet because you’re caught with it on the Stumpy!
I’m proud of the 800mm Roval bar and wouldn’t reduce it down. Getting a carbon bar can be a pleasant contact on a high-end bike just like the Stumpjumper 15 Professional.
Specialised’s Mirror Tech saddle is fairly comfy, however nothing magical… following the launch occasion my butt was a bit sore after two lengthy days of using! All through my typical using, the seat is sort of cozy although. Having a 185mm dropper publish is superb for a ‘medium’ (S3) body.
After a month of using the Roval Traverse SL II carbon wheels are exhibiting no harm in any respect and working completely true. The Specialised Butcher entrance and Eliminator rear tires have confirmed to supply good grip on all types of surfaces. I observed they did nice on a really rocky path, permitting me to creep down slabs with loads of management.
Lastly, the paint job on the Stumpjumper 15 Professional is fairly cool wanting. A few of the carbon weave reveals by way of the translucent inexperienced colour, and the end is textured to resemble raindrops on the body.
The Stumpjumper 15 Professional retails for $9,000. This mannequin comes within the Satin Inexperienced Tint/Gunmetal/Satin Metallic Sulphur colour solely.