• Sonder Cortex Frame in Khaki
  • Sonder Cortex frame in Battleship
  • Cortex Frameset
  • brown

    Cortex Frameset

    Short travel 29er


    or from £24 /month V12 logo


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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.


    Cane Creek DBair IL
    Cane Creek DBair IL 190 / 45



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      No Headset
      No Headset


      FSA Orbit C-40-ACB Headset
      FSA Orbit C-40-ACB Headset 7.8mm Spacer


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        Buy Now. In stock for same day despatch.

        With bang up to date geometry, Cortex is confidence inspiring 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 you grin. With 120mm travel and big wheels, Cortex is for mountain trails and down-country epics.

        At a glance

        Hand-welded from 6061 double butted aluminium frame for epic days over mixed terrain.

        • Fast and agile short travel full sus 29er; perfect for mixed terrain and day long epics
        • Frame: Sonder Cortex 120 mm travel, hand-welded 6061 double butted aluminium
        • Rockshox Deluxe Select+ / 190x45
        • Up to date geometry for trail bike agility and enduro bike stability

        Cortex frameset is hand-welded from 6061 double butted aluminium with a tapered ovalised top-tube and large section down-tube for a stiff chassis with just enough compliance to get you out of trouble. 66 head angle, 74.5 seat tube angle, 40 mm bottom bracket drop and a 465 mm reach (size large). Cortex’s dialed in geometry and 2.6" tyre clearance offers a comfortable and efficient climbing position for big miles and a stable, spirited platform for smashing up descents.


        Up to Date Trail Bike Geometry

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

        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.​

        Horst link suspension design

        The tried and tested Horst link suspension design allows the suspension to stay active when braking.​

        Tyre Clearance

        ​Clearance for up to 29 x 2.6in tyres.

        Internal Cable Routing

        ​Internal routing in the front triangle for clean lines.

        Build Spec
        BuildCortex Frame
        Frame:Cortex Frame
        Fork:No Fork
        Shock:Rockshox Deluxe Select+ / 190x45
        Frame:S: 1.97 kg; M: 2.0 kg; L: 2.1 kg; XL: 2.14 kg
        Built:S: 12.4 kg; M: 12.65 kg; L: 13.8 kg; XL: 13.9 kg
        Pedals not included with full builds 
        Geometry and Sizing


        It is important to get the right size bike, if the bike fits it will be faster, more comfortable, and easier to handle. You can also take into consideration the standover height to ensure you pick a bike that will be a good fit. If you measure your inside leg and ensure there is a minimum of an inch from the toptube to your crotch this will give you enough seatpost adjustment to find your optimum saddle height.

        Generally we recommend:
        Small: Riders between 5ft 2in and 5ft 7in (157-170cm)
        Medium: Riders between 5ft 6in and 5ft 10in (167-177cm)
        Large: Riders between 5ft 9in and 6ft 2in (175-187cm)
        X-Large: Riders of 6ft 2in + (187cm)


        Size Small Medium Large X-Large
        ST - Seat tube 405 425 465 485
        TT - Top tube 575.6 597.3 625.6 649
        HT - Head tube 100 105 115 125
        HA - Head angle 66 66 66 66
        SA - Seat angle 74.5 74.5 74.5 74.5
        CS - Chainstay 445 445 445 445
        BB - BB drop 40 40 40 40
        FO - Fork offset 46 46 46 46
        WB - Wheelbase 1169.1 1191.2 1220.2 1244.3
        SO - Stand over 749.7 768.4 782.6 796.6
        RE - Reach 420 440 465 485
        SK - Stack 601.7 606.3 615.4 624.6
        Frame Spec

        Alloy 29er short travel full suspension trail bike

        Weight: S: 2.8kg; M: 2.9kg; L: 3.0kg; XL: 3.08kg (without shock)
        Hydroformed and custom butted alloy frame tubing
        Internal cable routing
        Rear Shock: Rockshox Deluxe Select+ 190 x 45mm
        Horst link suspension layout
        120mm rear travel; 130mm fork travel
        Clearance for up to 29 x 2.6" wide tyres
        73mm BSA threaded bracket shell
        148 x 12mm rear thru-axle
        31.6mm seat tube, 34.9mm clamp
        Headset: IS42/28.6 | IS52/40 (not included)

        • Sonder Cortex Frame in Khaki
        • Sonder Cortex frame in Battleship
        • Cortex Frameset
        • brown