Specialized has unveiled an aluminium version of the Stumpjumper 15, which it released earlier this year.The new trail bike features the same geometry adjustment and Fox-developed Genie shock that's found on the carbon models, but is made from the brand's M5 alloy.The new Stumpjumper 15 Alloy will be available in three models, with prices starting at 2,750 / $3,000 / 3,250 / AU$4,900 for the Stumpjumper 15 Alloy and the coil-shock equipped Stumpjumper Fox Coil Alloy topping the range at 5,000 / $5,500 / 6,200 / AU$8,500.You can also choose a frameset-only option in some territories, priced at $2,300 / 2,600 / AU$3,900.Aluminium all-mountainThe frame has a similar outline to the carbon model. - SpecializedSpecialized had previously only offered the new Stumpjumper with a carbon construction, with this new model following the brands trend of adding aluminium options after an initial model release.Weve seen this with the Specialized Epic 8, which was followed by the new Chisel FS earlier this year.The new bike is made from the same M5 alloy as the Chisel FS, but sees more traditional tube forming, with the brands D'Aluisio Smartweld tech not featuring.The linkage is aluminium, as on most of the carbon variants. - SpecializedSpecialized has given the new Stumpjumper 145mm of rear-suspension travel, which is articulated via a Horst-linkage.Genie suspensionTwo positive air chambers are connected to increase overall air volume, although as the bike moves through its travel, the larger of the two becomes cut off, ensuring there's sufficient progression on offer to deal with the bigger impacts. - SpecializedThe US-based brand has co-developed a rear shock with Fox dubbed the Genie, which is claimed to give the bike 16.3 per cent better bump-force management than a traditional air-sprung shock.Specialized says this new shock gives the bike a long-travel feeling, while retaining the poppiness generally associated with trail bikes.Specialized has incorporated its SWAT frame storage into the down tube. - SpecializedIn essence, the new shock has a two-stage tuneable air spring that's said to improve traction without sacrificing big-hit control deeper into the travel.Two connected positive air chambers increase overall spring volume and remain open until the last 30 per cent of travel where the Genie band blanks them off, reducing spring volume and increasing ramp-up towards the end of the stroke.Specialized says the new Stumpjumper 15 Alloy uses the same amount of travel as its 170mm Specialized Enduro when absorbing a 1080 N bump force.Six geometry settingsThe Stumpjumper has high levels of geometry adjustment. - SpecializedLike the carbon fibre Stumpjumper 15, the frame features geometry adjustment that allows for six distinct settings.This is partly done via three different angles of headset cups, each of which offers an increase or decrease of one degree, with the neutral setting 64.5 degrees.There are also flip chips in the linkage pivots that enable you to adjust the bottom bracket height by 7mm, with the bike riding at 337mm in the high position.Setting the BB to the lowest position and using the slackest headset cup results in a seriously slack 63-degree head angle.While some may yearn for external cable routing, many will be pleased to see the lack of headset cable routing. - SpecializedThe bike features internal cable routing through the headset, a threaded bottom bracket and a SRAM Universal Derailleur Hanger, which should make maintenance and finding replacements easier.Specialized Stumpjumper 15 Alloy spec and priceSpecialized Stumpjumper 15 AlloyThe Stumpjumper 15 Alloy doesn't come with the Genie shock. - SpecializedFork: RockShox Psylo Silver, 150mm travelShock: X-Fusion 02 Pro RLDrivetrain: Shimano DeoreBrakes: Shimano BR-MT420Wheels: Specialized AlloyTyres: Specialized Butcher (f), Specialized Eliminator (r)Price: 2,750 / $3,000 / 3,250 / AU$4,900Specialized Stumpjumper 15 Comp AlloyThe Stumpjumper 15 Comp Alloy is the cheapest model to come with the Genie shock. - SpecializedFork: Fox Float 36 Rhythm, 150mm travelShock: Fox Float Performance with Specialized Genie Shock TechDrivetrain: Shimano SLXBrakes: TRP Trail EVOWheels: Specialized AlloyTyres: Specialized Butcher (f), Specialized Eliminator (r)Price: 3,750 / $4,500 / 4,500 / AU$6,200Specialized Stumpjumper 15 Fox Coil AlloyThe Stumpjumper 15 Fox Coil Alloy features a longer fork than the other two models. - Fork: Fox 38 Factory, 160mm travelShock: Fox DHX FactoryDrivetrain: Shimano SLXBrakes: TRP DHR-EVOWheels: Roval TraverseTyres: Specialized Butcher (f), Specialized Eliminator (r)Price: 5,000 / $5,500 / 6,200 / AU$8,500.