Buy Now

Cortex GX Eagle

Short travel 29er

£2,949.00

Fast and agile, Cortex is a trail riding, down-country, all terrain mountain bike for seriously epic days out. It ...

Cortex GX Eagle

Cortex GX Eagle
Cortex GX Eagle
Cortex GX Eagle
Cortex GX Eagle
Photos for illustration purposes. Please check the bike spec for detailed component listings.
sonder cortex in battleship grey gx axs pike
sonder cortex in khaki gx axs pike
Sonder Cortex GX Eagle Revelation in crayon
Sonder Cortex GX Eagle Revelation brown
Buy Now

Cortex GX Eagle

Short travel 29er

£2,949

Fast and agile short travel full suspension 29er mountain bike with SRAM GX Eagle drivetrain, Rockshox Pike Ultimate fork and Deluxe Select+ rear shock

Read more

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Buy Now. Hand Built in 5 days.

Buy Now

Cortex GX Eagle

Short travel 29er

£2,949

Fast and agile short travel full suspension 29er mountain bike with SRAM GX Eagle drivetrain, Rockshox Pike Ultimate fork and Deluxe Select+ rear shock

Buy Now. Hand Built in 5 days.

  • Please select

    • Customise

    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.

    Accessories

  • Handlebar

    • Sonder Aspect Riser 780mm

      • Sonder Aspect Riser [OEM]

      In general riser bars tend to be wider than flat bars and may have slightly more flex to give a more forgiving ride. As you go into descents and your arms drop below your knees the additional height gained on your front end will help you take control of the steep descents.

      That said you can get all bar types in a range of widths and stiffnesses and front end height can be adjusted with spacers like our Sonder Rings, so sometimes you just have to ignore the mumbojumbo and make your call on style and personal preference and there is nothing wrong with that.

    • Sonder Horizon Flat 720mm

      +£0

      • Sonder Horizon Flat [OEM]

      Flat bars help you keep the front end of your bike low, allowing you to get the weight over your front wheel when climbing and giving you more control in cornering.

      Our flats have a 5˚ rise so technically we should call them flatish, but if you really need them to be totally flat just rotate in the stem clamp!

    • Sonder Confucius

      +£24.99

      • Sonder Confucius

      Confucius says that you don't have to sacrifice what you love about your traditional riser bars just to get the flexibility of a hooped bar.

      We have taken our Aspect risers and evolved them in to a bar designed primarily for bikepacking. You won't have to adapt to a new hand position so you are not going to lose any control off-road and you can still get out of your saddle and power up the hills like a hero.

      If you do want to move your hands a bit a reduce the fatigue of a long ride, the hoop extends out front giving a choice of further hand positions. The bars also have a slight 'back sweep' so you can sit more upright in the saddle

      The bars have a slight riser but feel free to experiment and rotate them to your suiting. Keep them horizontal, or twist them up slightly to give yourself a streamlined TT style riding position to help you battle across a windblown Tierra del Fuego.

      Strength is not compromised as the main load bearing section of the bar is a single piece. Got gadgets? Confucius loves gadgets, and with the out-front hoop you can free up the bar around the stem. Simply attach your Garmin, 3000 lumen torches or mascots to the hoop and they will still be well within reach, maybe at an even better viewing angle and sit above your handle bar luggage.

      Take your bikepacking into the mountains; Confucius is a bar that gives you more control than a tradional swept back bar on technical terrain.

    Saddle

    • Sonder Abode Black / 138

      • Sonder Abode [OEM]

      High density foam padding over a plastic base provides comfort and longevity. A v-shaped split at the rear of the saddle allows flex as you are riding, increasing shock absorbancy and reducing pressure on the spot between your sit bones.

      Scooped up at the back with a slight rise towards the nose the longitudinal profile provides a cupped, craddled seating position, a timeless, proven design for distance on and off the road or climbing in the mountains.

      Stainless steel rails give 50 mm of forward and back adjustment to help you find your sweet spot.

      All our Sonder bikes come with Abode fitted as standard.

    • Sonder Zone 152 / Black

      +£29.99

      • Sonder Zone [OEM]

      The Zone is designed for maximum pedalling efficiency and comfort on longer rides, whether on road or off it.

      • Chromoly rails with suspension system
      • Cut-out shape relieves pressure
      • High density foam seat for comfort

      We’ve selected a flat saddle profile that’s long enough to allow for lots of micro-adjustments to your riding position over the course of a full day on the bike. The nose width allows you to move forward over the pedals on climbs and sprints, and a tapered back enables you to get behind the saddle easily for switchback descents or technical off-road sections.

      We’ve chosen a nylon fibre saddle base to provide a stiff and stable pedalling platform for a low overall weight. This base is connected to the chromoly rails using a patented suspension system that reduces road buzz and improves comfort without compromising on support.

      High density foam stays comfortable for longer, adding to the saddle’s supportive platform. And a long central cut-out in the middle of the Zone relieves pressure on the perineum, allowing you to ride for longer.

    • Sonder Kura

      +£34.99

      • Sonder Kura [OEM]

      Adventure cycling is diverse; in the course of a single trip you can find km's of asphalt, traverse rutted grasslands, weave through thickly forest singletrack, climb loose gravel track or descend steep rocky trails.

      It is unlikely you are going to find a single saddle position for all of this terrain. With this in mind Kura has a flat longitudinal profile with a gentle lateral curvature to give an extended saddle area, allowing you to position yourself around the saddle as you move between road, downhill, and climbing.

      The honeycomb base reduces weight whilst still providing structure and support that adapts and flexes with your motion.

      Titanium rails giving 50 mm of forward and back adjustment to help you find your sweet spot. Titanium is more forgiving than steel so provides a little more comfort.

      Slightly wider than our Adobe saddle, it may provide additional comfort for riders with wider sit bones.

    Seatpost

    • X-Fusion Manic Drop Seatpost and Lever 31.6mm / 150mm

      • X-Fusion Manic Drop Seatpost and Lever

      The X-Fusion Manic Dropper has been designed to work well across cross-country, trail, all mountain and enduro riding.

      It works on a simple design. Inside you’ll find a closed cartridge that is both sealed and designed to be easily removable from the rest of the post. Simple construction aside, the action of this post feels super-smooth and silky.

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

      • X-Fusion Manic Drop Seatpost and Lever

      The X-Fusion Manic Dropper has been designed to work well across cross-country, trail, all mountain and enduro riding.

      It works on a simple design. Inside you’ll find a closed cartridge that is both sealed and designed to be easily removable from the rest of the post. Simple construction aside, the action of this post feels super-smooth and silky.

    • RockShox Reverb / 125mm Drop / 31.6 x 390mm

      +£49.99

      • RockShox Reverb / 125mm Drop / 31.6 x 390mm

      The RockShox Reverb provides effortless actuation and increased reliability featuring new Vent Valve Technology.

      With reduced overall post lengths and new travel options, riders of all shapes and sizes benefit from more travel than ever before. The Reverb Stealth is just really, really reliable at simply going up and down.

    • RockShox Reverb / 150mm Drop / 31.6 x 440mm

      +£174.99

      • RockShox Reverb / 150mm Drop / 31.6 x 440mm

      The RockShox Reverb provides effortless actuation and increased reliability featuring new Vent Valve Technology.

      With reduced overall post lengths and new travel options, riders of all shapes and sizes benefit from more travel than ever before. The Reverb Stealth is just really, really reliable at simply going up and down.

    Stem

    • Sonder Piskie / 31.8mm / 35mm

      • Sonder Piskie [OEM] /

    • Sonder Piskie / 31.8mm / 45mm

      • Sonder Piskie [OEM] /

    • Sonder Piskie / 31.8mm / 55mm

      • Sonder Piskie [OEM] /

    • Sonder Talo 35

      +£34.99

      • Sonder Talo

      Talo is a sturdy CNC machined aluminium performance mountain bike stem with four bolt clamp to hold your bar firmly in place.

      Opposing bolts on the steer tube clamp give extreme clamping power while reducing stress on the steer tube. Machining shaves unnecessary weight to specifically engineer it for trail and all-mountain riding.

      It's built for the trail and stiff for its weight to give precise and immediate handling.

      • compatible with all 31.8mm handlebars and 28.6mm steerer tubes
      • 0° rise
      • 6061-T6 aluminium construction
      • Weighs just 127g (35mm length)
      • Available in 35mm and 45 mm lengths

      The humble stem has a significant effect on your bike's geometry and as a result its performance and your comfort. A shorter stem results in faster handling and a more upright riding position. Longer stems increase reach with slower more predictable handling.

      Experiment with different length stems or get a pro bike fit to hone your perfect set-up.

      Note. The length of a stem isn’t its overall length, from the very front to the very back, but the distance from the central point on the steerer tube and the centre of the handlebar.

       

    • Sonder Talo 45mm

      +£34.99

      • Sonder Talo

      Talo is a sturdy CNC machined aluminium performance mountain bike stem with four bolt clamp to hold your bar firmly in place.

      Opposing bolts on the steer tube clamp give extreme clamping power while reducing stress on the steer tube. Machining shaves unnecessary weight to specifically engineer it for trail and all-mountain riding.

      It's built for the trail and stiff for its weight to give precise and immediate handling.

      • compatible with all 31.8mm handlebars and 28.6mm steerer tubes
      • 0° rise
      • 6061-T6 aluminium construction
      • Weighs just 127g (35mm length)
      • Available in 35mm and 45 mm lengths

      The humble stem has a significant effect on your bike's geometry and as a result its performance and your comfort. A shorter stem results in faster handling and a more upright riding position. Longer stems increase reach with slower more predictable handling.

      Experiment with different length stems or get a pro bike fit to hone your perfect set-up.

      Note. The length of a stem isn’t its overall length, from the very front to the very back, but the distance from the central point on the steerer tube and the centre of the handlebar.

       

  • Forks

    • RockShox Pike Ultimate RCT3 29er / 130mm [OEM]

      • RockShox Pike Ultimate RCT3

    • Cane Creek Helm MK2 Air / 29 / 130mm 130mm

      +£149.99

      • Cane Creek Helm MK2 Air / 29 / 130mm

    Shock

    • Rockshox Deluxe Select+ / 190x45

      • Rockshox Deluxe Select+ / 190x45

    • Cane Creek DBair IL 190 / 45

      +£114.99

      • Cane Creek DBair IL

  • Tubes

    • WTB Inner Tube / 29 / 2.4 - 2.8 Black

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

    • Tubeless Tyre Upgrade and Setup

      +£44.99

      • Tubeless Tyre Upgrade and Setup

      Go tubeless

  • Lights accessories

    • No Bike Light Accessories (none)

      • No Bike Light Accessories

    • Helmet Mount Black

      +£4.99

      • Helmet Mount

      The Helmet Mount allows you to attach your Alpkit bike light to your helmet so you can scan the trail ahead and fly round sharp bends without having to wait for your handlebar light to catch up.

      The Velcro straps thread through your helmet vents and a three-pronged pivot with screw tightener allows you to adjust your lighting angle securely. The Helmet Mount is compatible with the Phase 400, Phase 800, Ariel, Hadron.

    • Garmin Outfront Mount / Black

      +£15.99

      • Garmin Outfront Mount

      The Garmin and Light Outfront Handlebar Mount combines two mounts on one arm so your bars aren’t covered in devices.

      Sticking out front, the twist lock Garmin mount makes it easier to route find and operate on the move. And you can attach your bike light underneath so your screen isn’t affected by any glare.

      The arm positions both your lights and GPS more centrally and is made from durable aluminium. The bracket attaches with screws and comes with an assembly pack so you can fit it securely.

      The mount fits the Phase 400, Phase 800, Ariel and Hadron lights.

  • Bottle cages

    • No Bottle Cages (none)

      • No Bottle Cages

    • Sonder Buzz Wire Single

      +£4.99

      • Sonder Buzz Wire

      The easiest and most convenient way to carry water on your bike, a classic cage design that holds your water bottle nice and snug.

      Buzz Wire is reassuringly durable, weighs just 65 grams and will carry your 500 or 750 ml water bottle with ease.

      If you are on expedition and looking for a way to pass a rest day make a bent wire loop and challenge someone to a game of Buzz Wire!

    • Sonder Buzz Wire Pair

      +£8.99

      • Sonder Buzz Wire

      The easiest and most convenient way to carry water on your bike, a classic cage design that holds your water bottle nice and snug.

      Buzz Wire is reassuringly durable, weighs just 65 grams and will carry your 500 or 750 ml water bottle with ease.

      If you are on expedition and looking for a way to pass a rest day make a bent wire loop and challenge someone to a game of Buzz Wire!

    • Sonder Sideblade Black / Left Entry

      +£5.99

      • Sonder Sideblade

      The Sideblade bottle cage not only gives your water bottle a lovely, secure hug, but its side loading system makes it easier to access when you need a drink, making staying hydrated a joy even when you've got a load of frame bags to work around!

      The Side blade is geared at letting you get to your water when you've got a bike packed up with frame bags, this means that it's also ideal for compact and full-sus frames where a standard loading bottle cage system just won't fit, you can choose which side you'd like to access your bottle by with a twist of the cage in the mount before your ride.

      Made of polycarbonate, the Sideblade is also super light and super duper tough - hooray!

    • Sonder Sideblade Black / PAIR

      +£7.99

      • Sonder Sideblade

      The Sideblade bottle cage not only gives your water bottle a lovely, secure hug, but its side loading system makes it easier to access when you need a drink, making staying hydrated a joy even when you've got a load of frame bags to work around!

      The Side blade is geared at letting you get to your water when you've got a bike packed up with frame bags, this means that it's also ideal for compact and full-sus frames where a standard loading bottle cage system just won't fit, you can choose which side you'd like to access your bottle by with a twist of the cage in the mount before your ride.

      Made of polycarbonate, the Sideblade is also super light and super duper tough - hooray!

    Lights

    • No Lights (none)

      • No Lights

    Mudguards

    • No Mudguards (none)

      • No Mudguards

    • Sonder Fender Front MTB

      +£4.99

      • Sonder Fender

      The Sonder Front Fender protects you from excessive mud splatter on wet, mucky trails. These lightweight plastic mudguards don’t require any special fixings on your bike and can be strapped straight onto your forks with 4 cable ties (supplied).

      Made from durable polypropylene, if the Fender does meet its end, it can be easily recycled by most councils or at your local recycling centres.

    Pedals

    • No Pedals (none)

      • No Pedals

    • Sonder Torque Black

      +£29.99

      • Sonder Torque

      Combining the Comfort of plastic with the grip of metal pedals. 

      A tough large platform, thin profile thermoplastic body with replaceable steel pins. The Cromoly axle gives durability and strength that you can depend on.

      LSL bushing combined with a sealed bearing keeps the pedals turning in all weather conditions.

      We have tried and tested these pedals and they have stayed true through winter and summer trails.

    • Sonder Reko

      +£50.99

      • Sonder Reko

      The Reko are lightweight SPD pedals designed gravel riding and cross-country mountain biking over longer distances.

      The Reko's platform-free design reduces the overall weight of the pedals to 145g per pedal for lighter, faster riding. Double-sided SPD bindings are easy to clip in and out of and their compact design means they're less likely to clog with muck on filthy winter rides.

      The clip-in design improves the efficiency of your pedal strokes, saving energy on long rides and improving power transfer on climbs, and gives you more control of the back end of the bike.

    • Sonder Jekyll Black

      +£59.99

      • Sonder Jekyll

      Jekyll is two faced; SPD's and flats all in one, multi-purpose mtb touring pedals.

      Jekyll gives you the freedom to ride with normal shoes or with cleats. Jekyll combines a single sided SPD mechanism with a flat pedal body with grip pins on the other. They are ideal for riders who switch frequently from the daily commute to nipping down to the local shop for a pint of milk in their loafers.

      The flat side has 8 replaceable grip pins, 4 mm long, they provide grip in all conditions. When you are ready to get your power on the cleats are just a half rotation away - no swapping your pedals out.

      Jekyll also comes provided with Sonder 'SH-51 style' cleats.

    • Sonder Slingshot Black

      +£59.99

      • Sonder Slingshot

      The wide platform Slingshot pedal is designed to provide the support, control and confidence you need for a variety of riding, whether on trail, gravel or road.

      • Wide 87x90 platform made from 6061 aluminium
      • Double-sided adjustable SPD clips
      • Chromoly axle with sealed bearings

      The Slingshot's wide foot platform provides plenty of support to the foot for more comfortable pedalling over long distances, reducing hot-spots. This additional foot support also gives you greater control of the rear end of the bike on tight turns or technical trail.

      If you're using the Slingshot for mountain biking, the pedal's wide surface gives you a platform to stand on unclipped, ready to bail out if needed, on heart rate-quickening sketchy sections.

      With double-sided SPD clips and a large pedal area, the Slingshot is easy to clip in and out of in a hurry. A clipless system provides greater pedalling efficiency when climbing and more control when descending.

Initial Price
£2,949
Frame
Cortex GX Eagle
Size
Colour
Extras
£0
Total Price
£2,949

Buy Now. Hand Built in 5 days.

Description

Fast and agile, Cortex is a trail riding, down-country, all terrain mountain bike for seriously epic days out. It comes alive on long technical descents with 120 mm rear travel, big wheels and a stiff responsive frame.

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.

..Read more

At a glance

  • SRAM GX Eagle 12-speed groupset
  • Rockshox Pike Ultimate fork
  • Rockshox Deluxe Select+ shock
  • Superstar 29" wheelset

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.

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Features

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
Frameset
Frame:Cortex Frame | 6061 aluminium
Fork:RockShox Pike Ultimate | 130mm (travel)
Shock:RockShox Deluxe Select+ | 190 x 45
Headset:FSA Orbit C-40-ACB
Groupset
Shifters:SRAM GX Eagle Trigger | 1x | 12-speed
Brakes:SRAM G2 R | Hydraulic | Post Mount
Rotors:SRAM Centreline | 180mm (front), 160mm (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 GX 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:XS: TBC S: 2.80kg; M: 2.90kg; L: 3.0kg; XL: 3.08kg;
Build:XS: TBC S: TBC M: 13.47kg; L: TBC XL: TBC
Pedals not included with full builds
Specifications are subject to change without notice
Geometry and Sizing

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)

Transmitter

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 52 52 52 52
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

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