Specialized didn’t invent mountain biking, the Nobel prize for that should go to the Repack races in Marin County in the 1970s. What Mike Sinyard’s brand does lay claim to is the first production mountain bike; the Stumpjumper. Released in 1981, Sinyard’s gamble meant you could actually walk into a shop and buy a machine purpose built for mountain biking rather than cobbling something together from an old beach cruiser or getting a frame builder to weld one together to order, which was a slow process indeed. Naturally this made things more affordable for more people than getting a bespoke bike, although at around $800 for the Stumpjumper it wasn’t exactly a cheap hardtail – allowing for inflation, an $800 bike would cost $2,500 at today’s prices.

The Specialized Stumpjumper at 40 – no sign of any wrinkles!

“So this was the disrupter if you like,” explains Richard Salaman from Specialized. “There’s an advert we used at the time that says ‘It’s not just a new bicycle, it’s a whole new sport,’ and it really was. It was that sort of level of bike, this isn’t a road bike with funny handlebars, this is a totally different concept.”

Ahead of its time, not only as the first production mountain bike, but the slack head angle, wide riser bars and long chainstays are now back on trend after a decade of trying to emulate road bikes with twitchy geometry and ‘aero’ riding positions.

So in honour of 40 years of the Stumpjumper, and to tie in with our own 25 year anniversary, we borrowed a bike from the second production run in 1982 (originals are rare) from Specialized UK to find out why the Stumpy made such a big splash.

Mill Valley Cyclery is no more, but there’s still a bike shop on Miller Avenue at the foot of Mt Tam (where the Repack races were held).

Frame

Japan was the industrial powerhouse of the world in 1982, and it’s here Specialized went to have its first frames brazed up using lugs at the tube junctions. In 1982 the bike would have arrives at the dealer literally in pieces – frame, headset, BB, drivetrain, and so on – and it was up to the shop to build it up for you. This bike was assembled by Mill Valley Cycles from Marin County, part of a run of just 500 bikes.

Lugs were commonplace on early bikes but they were heavy and limited geometry, so soon fell out of favour.

There’s nothing alloy on the Stumpy frame, the tubing is made from double butted cro-mo steel, a process that reduced frame weight, increased stiffness and moved the stress points away from the head tube and spread it over the entire frame. This process was common on high end road frames at the time, which used Reynolds 531 tubing.

Now that’s what we call a head tube.

The head tube itself is straight with a 1in bore, it took a decade for 1 1/8in head tubes to become prevalent, while there’s a clutch of great little details that would seem too fussy or intricate today. The cable for the front mech doesn’t run under the BB shell, instead there’s a beautiful little guide welded to the top of the BB shell, while the thinnest strip of metal adorns the driveside chainstay – made from steel it’s there to stop the chain literally cutting through and making holes in the frame.

Suspension forks wouldn’t appear for almost a decade when the Stumpjumper came out, so it was all about trusty rigid forks like this one. The crown would have been forged or cast, then the legs brazed in.

Fork

This is the second generation fork Specialized made and doesn’t have a simple unicrown construction. Instead there are two struts, and that makes the fork stiffer and assembly easier. There are bosses on the fork to mount mudguards or a rack because the first mountain bikes were marketed as “adventure machines,” Specialized said, designed to get away from urban life and back into nature.

After melting numerous coaster (back-pedal) brake hubs, cantilever brakes were borrowed from touring bikes to provide sufficient power and better reliability. They also brought their own suite of problems, such as wearing through rims and not working in the wet.

Brakes

In 1982 the V-brake had yet to be invented, and the disc brake was for cars and motorbikes. Road brakes weren’t powerful enough for mountain biking, so Specialized turned to touring cantilevers for their power, twinned with motorbike levers from Tomaselli – the  lever increased the power of the brake, and engaged more cable for better control. This bike would originally have come with Mafac touring brakes, but they’ve been upgraded to Shimano cantis, probably from 1983.

The bullmoose stem and cowhorn bar combo gave loads of leverage and control. Then the MTB world decided that flat, 150mm long stems and 500mm bars were better, and confident handling characteristics were thrown out of the window.

Components

Components for the first Stumpjumpers were borrowed from different disciplines. The 1982 model came with a modified BMX stem and steel bars based on Magura’s motorbike handlebars (the original rubber grips are starting to perish, but actually feel soft and malleable to the touch). Component brand Tange supplied a road headset, and the vast Avocet saddle is straight off a touring bike.

Alloy rims with reinforced nipples were a game changer compared to the heavy, flexy steel wheels of the original clunkers. It would be thirty years before the original 26in diameter was really challenged.

Wheels

The Stumpjumper used alloy rims it branded Saturne, a big change from the steel wheels of the original clunkers that were heavy and flexy and wouldn’t stay true. This example is running on an original 26in wheel with an alloy hub, and 36 plain gauge steel spokes complete with brass nipples. Other brands were making small wheels like this, but not to the same strength required for mountain biking, so Specialized had Tom Ritchey make up the rims using reinforced eyelets to stop the spokes pulling out. Wheels are held in place with solid bolts rather than quick release axles, although it’s interesting Specialized did think to put a QR lever on the seatpost to raise and lower the saddle. The tyres measure just 1.25in across.

Gears on the original Stumpjumper weren’t even indexed – there were no clicks between sprockets – so you had to move the lever until the chain ran smoothly. How about that integrated cable clamp and hidden cable, though? Sleek.

Drivetrain

In 1982 the Italians made the most prestigious road bike drivetrains, but mountain bikers weren’t concerned with history… because there was none. Specialized turned to Japanese component brand Sugino for the crankset and Suntour with its new Le Tech rear mech and oh-so-80s font. The bike uses a 18-30t cassette and a triple chainring with 46-36-26 chainrings. That gives a pretty meage 295% gear range, or just over half that of modern bikes equipped with SRAM Eagle 12-speed.

2022 Specialized S-Works Stumpjumper Evo is almost unrecognisable from its ancestor

The great, great grandchild – 2022 S-Works Stumpjumper Evo

Testament to Mike Sinyard’s vision, the Stumpjumper is still a hugely successful model today, and arguably the most well known model name on the market. In the 2022 Specialized range there are 18 Stumpjumper models sold in the US, with nine regular versions and none Evo options. And for a brand who’s motto was ‘innovate or die’, this Evo model in particular boasts several cutting-edge features. The striking asymmetric frame employs what Specialized has dubbed the ‘Sidearm’ to stiffen the front triangle against big impacts and hard landings. This slender strut links the fore and aft shock mounts, ensuring that the top tube and seat tube don’t pull away from each other at full travel on harsh landings. Next there’s the innovative SWAT internal frame storage – a highly practical idea that utilises the space inside the down tube for storage. Unclip the door (which holds the bottle cage) and there’s room for tools, a spare tube, snacks and even a packable jacket.

SWAT compartment is a useful feature and cage holds handy mini-tool

Another area in which the latest Stumpjumper Evo heads the field is geometry adjustment. On the latest bike you can manipulate the chainstay length and BB height independently of the head angle and reach. There’s even the opportunity to convert to a mullet wheel set-up too, using an optional link. In total there are six different settings, and this gives riders impressive flexibility to configure their bike and its handling characteristics according to their personal preference and local terrain. And by keeping the seat tubes short and the standover height consistent across the six size range, riders can choose the size of their bike based on wheelbase and reach rather than how high they run their saddle for pedaling.

Flip-chip pivots further expand the Stumpy EVO’s range of set-up options

While the Stumpjumper is the longest running model on the market, it’s also one of the very best. In our recent Trail Bike of the Year test, the 2022 Stumpjumper Evo Comp earned a perfect 10/10 rating, garnering praise such as this in the process: “Not only is the Stumpy Evo Comp drop-dead gorgeous, it’s mega-adjustable and adaptable, comes with integrated storage and you can ride it harder than any other trail bike in that category”.