• Cortex SLX in Mint
  • Cortex GX Eagle
  • Cortex GX Transmission in Storm Blue
    • Special Offer

    Cortex GX Eagle

    Mid travel 29er

    £2,699 £2,999

    or from £47 /month V12 logo

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    Fast and agile mid travel full sus 29er mountain bike with Sram GX 1x12 groupset, Rockshox Pike fork and Deluxe rear shock
    Buy Now. Be Riding Next Week.

    Need help choosing a bike or technical advice?

    • Open a Live Chat
    • Pop into a store 7 days a week
    • Call a Sonder Customer Hero on 01773 417006
    • Email us at support@alpkit.com

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    • Size
    • Colour
    • Size:

    • Colour:

    • Customise and buy now. Deliveries from 18th July

    2

    Customize

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    Every Sonder bike is built to order so tell us exactly how you want it. Make any changes you want from the standard build and when you're done, just hit “Add to Bag” at the bottom of the page.

    Handlebar

    Sonder Aspect Riser [OEM]
    Sonder Aspect Riser 780mm

    +£0.00

    Sonder Aspect Riser [OEM]
    Sonder Aspect Riser 780mm

    +£0.00

    sonder aspect carbon flat handlebar flatbar
    Sonder Aspect Carbon Riser 780mm

    +£99.99 +£64.99

    sonder scope handlebars
    Sonder Scope Handlebar 760mm

    +£39.99 +£32.49

    Saddle

    Sonder Abode [OEM]
    Sonder Abode Black / 138

    +£0.00

    Sonder Zone [OEM]
    Sonder Zone 133 / Black

    +£34.99 +£29.99

    Sonder Zone [OEM]
    Sonder Zone 152 / Black

    +£34.99 +£29.99

    Sonder Kura [OEM]
    Sonder Kura

    +£47.99 +£39.99

    Seatpost

    X-Fusion Manic Drop Seatpost and Lever
    X-Fusion Manic Drop Seatpost and Lever 31.6mm / 125mm

    +£0.00

    X-Fusion Manic Drop Seatpost and Lever
    X-Fusion Manic Drop Seatpost and Lever 31.6mm / 170mm

    +£0.00

    Stem

    Sonder Piskie [OEM]
    Sonder Piskie 31.8mm / 35mm

    +£0.00

    Sonder Piskie [OEM]
    Sonder Piskie 31.8mm / 45mm

    +£0.00

    Sonder Piskie [OEM]
    Sonder Piskie 31.8mm / 55mm

    +£0.00

    sonder talo bike stem
    Sonder Talo 35

    +£44.99 +£37.49

    sonder talo bike stem
    Sonder Talo 45mm

    +£44.99 +£37.49

    Forks

    RockShox Pike [OEM] / 29 / 140mm
    RockShox Pike / 29 / 140mm

    +£0.00

    RockShox Pike Ultimate [OEM] / RC2 / Charger 3.1 / 29 / 140mm
    RockShox Pike Ultimate / RC2 / Charger 3.1 / 29 / 140mm

    +£399.99

    Cane Creek Helm MK2 Air [OEM] / 29 / 140mm
    Cane Creek Helm MK2 Air / 29 / 140mm

    +£699.99

    Shock

    Rockshox Deluxe Select+ / 210 / 50
    Rockshox Deluxe Select+ / 210 / 50

    +£0.00

    Rockshox Deluxe Ultimate / 210 / 50
    Rockshox Deluxe Ultimate / 210 / 50 Black

    +£149.99

    Cane Creek DBair IL / 210 / 50
    Cane Creek DBair IL / 210 / 50 Black

    +£299.99

    Tubes

    WTB [OEM] Inner Tube / 29 / 2.4 - 2.8
    WTB Inner Tube / 29 / 2.4 - 2.8 Black

    +£0.00

    Tubeless Tyre Upgrade and Setup
    Tubeless Tyre Upgrade and Setup

    +£44.99

      3

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      Edit

      Bottle Cages

      No Bottle Cages
      No Bottle Cages (none)

      +£0.00

      Sonder Buzz Wire
      Sonder Buzz Wire Single

      +£5.49 +£4.99

      Sonder Buzz Wire
      Sonder Buzz Wire Pair

      +£10.99 +£8.99

      love mud side blade side loading bottle cage left
      Sonder Sideblade Black / Left Entry

      +£6.99 +£5.99

      love mud side blade side loading bottle cage left and right
      Sonder Sideblade Black / PAIR

      +£9.99 +£7.99

      love mud side blade side loading bottle cage right
      Sonder Sideblade Black / Right Entry

      +£6.99 +£5.99

      Sonder Blade
      Sonder Blade Black

      +£17.99 +£14.99

      Sonder Blade
      Sonder Blade Black / Pair

      +£29.99 +£24.99

      Ti Wire Bottle Cage
      Ti Wire Bottle Cage Single

      +£44.99 +£37.49

      Ti Wire Bottle Cage
      Ti Wire Bottle Cage Pair

      +£79.99 +£64.99

      Front Lights

      No Front Light
      No Front Light (none)

      +£0.00

      Tau
      Tau Front

      +£16.99 +£14.99

      Phase 550
      Phase 550

      +£24.99 +£19.99

      Phase 850
      Phase 850

      +£34.99 +£29.99

      Rear Lights

      No Rear Light
      No Rear Light (none)

      +£0.00

      Lights Accessories

      No Bike Light Accessories
      No Bike Light Accessories (none)

      +£0.00

      alpkit helmet mount bike light gps
      Helmet Mount Black

      +£7.99 +£6.99

      alpkit cockpit bike light gps mount
      Garmin Outfront Mount / Black

      +£24.99 +£19.99

      Mudguards

      No Mudguards
      No Mudguards (none)

      +£0.00

      sonder fender
      Sonder Fender Front MTB

      +£6.99 +£5.99

      Pedals

      No Pedals
      No Pedals (none)

      +£0.00

      Sonder Torque
      Sonder Torque Black

      +£39.99 +£32.49

      reko clipless bike pedal
      Sonder Reko

      +£49.99 +£39.99

      distortion flat mountain bike pedal
      Sonder Distortion

      +£59.99 +£49.99

      sonder slingshot clipless pedal
      Sonder Slingshot Black

      +£79.99 +£64.99

      sonder Jekyll clipless and flat hybrid pedal
      Sonder Jekyll Black

      +£79.99 +£64.99

        Initial Price

        Cortex GX Eagle / Select a frame...
        £2,699.00

        Extras

        £0.00

        Total Price

        £2,699.00
        V12 Interest Free Finance
        Buy Now. Be Riding Next Week.

        Fast and agile, Cortex is a mid-travel full suspension trail bike for big mountain epics on all terrain and flying round your local trail centre. It comes alive on long technical descents with 140mm travel up front and 135mm at the rear, big wheels and a stiff, responsive frame.



        With bang up to date geometry, Cortex inspires confidence with a playful character. Stand up and mash on the pedals out of turns, manual sections of trail and pop off tree stumps, rocks and roots. Smash out short and loose technical climbs, flat-out descents and tight techy singletrack sections. The harder you push the bigger your grin.

        The tried and tested Horst link design keeps the suspension active when braking. We've fine tuned the leverage curve and worked with SRAM RockShox to produce a rear shock that's custom-tuned for the Cortex - maximum downhill performance while maintaining the all-day pedalling efficiency from its predecessor. Cortex is your do-it-all bike of choice for lakeland 30-milers and flat-out trail centre laps alike; with enough travel to carry speed over longer sections of rough ground and a lively, playful feel through the twisty bits.

        Cortex' frameset is hand-welded from 6061 double-butted aluminium for the perfect mix of weight, rigidity and durability; with a slim hydroformed top-tube and down-tube designed to improve stiffness with just enough compliance to get you out of trouble. Internal cable and stealth dropper routing means clean lines, dampened with foam liners for a quiet ride. Dialed-in geometry and 2.4” tyre clearance gives heaps of grip; a comfortable and efficient climbing position for big days in the saddle; and a stable, spirited platform for smashing down descents.

        Why SRAM GX Eagle?

        Simple, light, tough, and reliable; the SRAM GX Eagle understands that when adventure is on the cards, all you want to do is put your feet on the pedals and ride. No faff. The 12 speed, 10 – 50 tooth groupset combines easy-going versatility with maximum performance, giving crisp shifting, quiet operation, and silky smooth pedalling feel.

        A super wide gear range lets you dictate your pace, whether you’re tackling tough inclines, sprinting on the flats, or letting loose on the descents. An open design facilitates mud clearance and boosts durability. The GX crankset, with 2 tooth profile chainring, bolsters ultimate chain control, and Flowlink technology enhances chain guiding, increases longevity, and heightens wear resistance.

        Features

        Up to date trail bike geometry

        Trail bike agility with Enduro bike stability, the Cortex has a confidence inspiring, stable and responsive ride.

        Increased chainstay length for the Large and XL frames maintains consistent weight distribution for riders of all heights.

        Metric Shock Standard

        Designed around metric shock sizing standard, with lengthened shocks and shorter strokes that increase bushing overlap for more smooth, supple, sensitive and reactive suspension action. We've worked with SRAM to produce a rear shock that's specifically tuned for the Cortex - and made sure those benefits are felt across a wider range of rider size and weight.

        140mm travel at the front and 135mm at the rear lets you carry higher speeds over rough ground without sacrificing pedalling efficiency.

        Horst link suspension design

        The tried and tested Horst Link suspension design allows the suspension to stay active when braking. We've fine-tuned the suspension leverage curve to maximise performance on the downhill while maintaining efficient uphill pedalling - so no need for climb switches.

        Internal cable routing

        Internal routing in the front triangle makes for clean lines and tidy cables, with dampened foam liners for a quiet ride.

        Universal Derailleur Hanger UDH

        Keeping up with industry standards, Cortex uses a UDH hanger. They're widely available so you can get rolling again sooner after any mid-ride mishaps!

        The UDH also makes Cortex compatible with the latest SRAM Transmission groupsets.

        Build Spec
        Frameset
        Frame:Cortex Frame | 6061-T6 Aluminium, Heat-Treated
        Fork:RockShox Pike | 140mm (travel)
        Shock:RockShox Deluxe Select+ | 210 x 50
        Headset:FSA Orbit C-40-ACB
        Groupset
        Shifters:SRAM GX Eagle Trigger | 1x | 12-speed
        Brakes:SRAM G2 R | Hydraulic | Post Mount
        Rotors:SRAM Centerline | 200mm (front), 180mm (rear) | 6-bolt
        Rear derailleur:SRAM GX Eagle | Long cage | 12-speed
        Chainset:SRAM GX Eagle DUB | 170mm | 32t
        Cassette:SRAM XG1275 Eagle | 10-52t | 12-speed
        Chain:SRAM NX Eagle | 12-speed
        Bottom bracket:SRAM DUB | BSA | 73mm
        Wheelset
        Wheels:Sonder Alpha 29" UK Made
        Front tyre:Goodyear Newton MTF Trail Tubeless | 29 x 2.5" | Black
        Rear tyre:Goodyear Newton MTR Trail Tubeless | 29 x 2.4" | Black
        Tubes:WTB | 29 x 2.4-2.8"
        Finishing kit
        Handlebars:Sonder Aspect Riser | 780mm
        Stem:Sonder Piskie
        Seatpost:X-Fusion Manic | 31.6mm
        Saddle:Sonder Abode
        Grips:Sonder Clutch | Black
        Weight
        Frame:S: TBC M: TBC L: TBC XL: TBC
        Build:S: TBC M: TBC L: TBC XL: TBC
        Pedals not included with full builds
        Specifications are subject to change without notice
        Geometry and Sizing

        Sizing

        SizeSmallMediumLargeX-Large
        Rider Height

        5ft 2in - 5ft 7in 

        (158-173cm)

        5ft 6in - 5ft 10in

        (170-177cm)

        5ft 9in - 6ft 2in

        (175-187cm)

        6ft 2in + 

        (187cm +)

        ST - Seat tube400410440460
        ETT - Estimated top tube576597625647
        HT - Head tube100105115125
        HA - Head angle65656565
        AC - Axle to crown550550550550
        SA - Seat angle75.675.675.675.6
        CS - Chainstay440440445445
        BB - BB drop40404040
        FO - Fork offset44444444
        WB - Wheelbase1173119512291253
        RE - Reach420440465485
        SK - Stack608614624633
        Frame Spec
        Weight: S: TBCkg; M: TBCkg; L: TBCkg; XL: TBCkg (plus shock 0.4kg)
        Hydroformed and custom butted alloy frame tubing
        Internal cable routing
        Rear Shock: 210x50mm metric shock – Custom tuned for the frame
        Horst link suspension layout
        135mm rear travel; 140mm fork travel
        Frame clearance for up to 29 x 2.4" wide tyres
        BSA BB with ISCG-05 chain guide tabs
        UDH Boost 148 x 12mm rear thru-axle
        31.6mm seat tube, 34.9mm clamp
        Headset: ZS44/28.6 top, ZS56/40 bottom

        • Cortex SLX in Mint
        • Cortex GX Eagle
        • Cortex GX Transmission in Storm Blue