Buy Now

Frontier SX Eagle Rigid

Multi-activity trail bike

£849.00

Frontier is our multi-activity hardtail mountain bike. Ride hard at the trail centre, load it up for a midweek bik...

Frontier SX Eagle Rigid

Photos for illustration purposes. Please check the bike spec for detailed component listings.
Buy Now

Frontier SX Eagle Rigid

Multi-activity trail bike

£849

Quick, lightweight 29er modern mountain bike with SRAM SX Eagle 1x12 groupset, Rigid Aluminium fork and Sonder Nova wheelset.

Read more

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Need help choosing a bike or technical advice?


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  • Pop into a store 7 days a week
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Buy Now. We'll build yours in 5 - 10 days.

Buy Now

Frontier SX Eagle Rigid

Multi-activity trail bike

£849

Quick, lightweight 29er modern mountain bike with SRAM SX Eagle 1x12 groupset, Rigid Aluminium fork and Sonder Nova wheelset.

Buy Now. We'll build yours in 5 - 10 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.

    Saddle

    • Love Mud Abode / 138

    • Love Mud 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 133 / Black

      +£24.99

    • 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

      +£19.99

    • 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.

    • Brooks Cambium C17 Saddle All Weather Carved / Black

      +£69.99

    • Brooks Cambium C17 Saddle

      Not the chafe. The dreaded chafe. Once it begins, there’s no stopping the creep along your bum cheeks, every slight movement adding to the sting.

      Banish bum cheek blues with the Cambium C17. Based on the underlying structure of the classic Brooks B17 leather saddle, the Cambium C17 uses a vulcanised rubber base and organic cotton canvas upper for the top. Unlike leather, the top material is waterproof, completely maintenance-free, and eliminates the wearing-in process of a leather saddle.

      The saddle top is hung over the nose piece, rails and rear metal cantle like a hammock. This design, when combined with the saddle’s supple materials, allows the saddle to move with the rider, reducing chafing whilst still providing support. The C17 Cambium is narrower and a little racier in design than the B17.

    • Brooks B17 Saddle Standard / Black

      +£64.99

    • Brooks B17 Saddle

      Manufactured in the UK, a tough 5mm thick leather top is stretched from a thin metal cantle plate at the rear, over the rails to the nose piece and secured by rivets. This durable leather top eventually wears to the shape of the user’s ‘sit bones’ for a superior riding experience. With the right leather-care a Brooks saddle can easily last a lifetime of riding.

      It may seem counterintuitive, but firm and less cushioned saddles are proven to reduce friction while cycling which protects against chafing and rubbing. Should the hammock-like design of the saddle start to sag too much, the leather can be re-tensioned by tightening a bolt in the nose piece.

    Seatpost

    • Sonder Seatpost 31.6mm / 400mm

    • Sonder Seatpost [OEM]

      A seat post that is reliable and offers adjustability to help you find your ultimate riding position.

      Membar is all about adjustability. With a twist of your allen key the micro adjustment rail clamp allows the saddle angle to be fine tuned to your ideal position.

      Your saddle can be fitted with minimal faff thanks to a quick release action that allows the upper rail clamp to be released without removing the retaining bolt. The lower rail clamp is secured to the seat post which means that it will not fall in the mud when you are trying to fit your saddle.

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

      +£119.99

    • 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

      +£174.99

    • 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.

    • Cane Creek EE-Silk 31.6mm / Alloy

      +£179.99

    • Cane Creek EE-Silk [OEM]

      Ride longer, ride further with the Cane Creek eeSilk suspension seatpost.

      At 295g the eeSilk Post is comparable in weight to traditional rigid seatposts while offering 20mm of vertical compliance to help improve control on rough surfaces and reduce fatigue on long rides. It's the sort of upgrade you thank yourself for 6 hours into a ride!

  • Tubes

    • Tubeless Tyre Upgrade and Setup

      +£44.99

    • Tubeless Tyre Upgrade and Setup

      Go tubeless

    Wheels

    • Sonder Nova XC Wheelset Shimano

    • Sonder Nova XC [OEM] Wheelset

      The Nova 29 XC is our entry level cross-country wheelset, allowing you to run narrower, lighter tyres on longer or less-technical rides.

      • Tubeless compatible and optimised for 2.0” – 2.4” tyres
      • 6061 alloy rims with plain gauge steel spokes
      • Sealed bearings for lower maintenance

      The Nova 29 XC’s 23m internal width is optimised for 2.0” to 2.4” tyres, accommodating narrower, lighter cross-country designs. Pre-taped they’re fully tubeless compatible for extra weight savings and reduced rolling resistance. The rims are made using light and reliable 6061 alloy with plain gauge steel spokes for extra durability.

      The Nova hubs are fully-sealed for low maintenance and are designed around modern Boost spacing standards. The hubs also use a steel body to survive years of abuse.

      With a lower weight than wider MTB rims, the Nova 29 XC spin up to speed quicker and require less effort to keep moving. Swap them into existing bikes set-ups for longer rides or upping your speed on faster, less technical singletrack.

    • Sonder Nova 27.5+ Wheelset Shimano

      +£0

    • Sonder Nova 27.5+ [OEM] Wheelset

      Whether you're navigating rock gardens or tackling steep climbs, Novas will consistently give you a boost when the roads are rough and the terrain is tricky. Machine built for precision on Sonder’s sealed hubs.

      Our design team’s expertise along with the factories we use mean that we can accelerate trickle-down technology to this price point.

      Boost: wider, stiffer, tougher

      Nova's boost hub is wider than a standard hub; extra width between the flanges promotes a shallower spoke bracing angle to create a stronger, stiffer wheel. A wider hub also means a shorter chainstay, more mud clearance, and better tyre clearance.

      Wider rims mean tyres work better

      38mm lightweight aluminium rims make this wheelset ideal for rock gardens and technical terrain – you can run 2.6" - 3" tyres, which will plump up really nicely to give a broad contact patch for maximum traction and confidence.

      Built to take abuse

      Novas have sealed bearings that are easily serviceable without the need for specialist tools. Plain-gauge spokes have been chosen to keep the wheels super-strong, whether you’re landing big drops or loading your bike with luggage. And a steel free-hub body will take years of abuse. You could go round the world on these wheels.

    • Sonder Alpha 27.5 HG

      +£149.99

    • Sonder Alpha 27.5 [OEM]

      Alphas are our performance 27.5" wheelset for big hits and big tyres. Whether you're riding down Top Chief at Fort William or riding the black routes at Bike Park Wales, Alphas will consistently spin up to speed and keep rolling to help you ride with fluid precision over the trails.

      Our design team’s expertise along with the factories we use mean that we can accelerate trickle-down technology to this price point.

      Alpha hubs: wider, stiffer, tougher, faster

      Alpha’s boost hub is wider than a standard hub; extra width between the flanges promotes a shallower spoke bracing angle to create a stronger, stiffer wheel. A wider hub also means a shorter chainstay, more mud clearance, and better tyre clearance. To make them faster we’ve used a 6 pawl freehub, which gives 120 points of engagement for immediate response when you turn the pedals (most hubs only have 60, which means you have to turn the pedals further before engaging the freehub). Oh, and the hubs sound amazing! Finally, sealed cartridge bearings just keep rolling and rolling.

      Wider rims mean tyres work better

      35mm lightweight aluminium rims make this wheelset ideal for rock gardens and technical terrain – you can run 2.4" - 3" tyres, which will plump up really nicely to give a broad contact patch for maximum traction and confidence.

      Built to take abuse

      Alphas have sealed bearings that are easily serviceable without the need for specialist tools. Double-butted spokes have been chosen to keep the wheels super-strong, whether you’re landing big drops or loading your bike with luggage. And a 17mm alloy axle make these hubs super-stiff and super-strong. You could race round the world on these wheels. Silk Road Mountain Race here we come!

  • Pedals

    • No Pedals (none)

    • No Pedals
    • 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.

  • Bottle cages

    • No Bottle Cages (none)

    • No Bottle Cages

    Lights

    • No Lights (none)

    • No Lights
      -
    • Tau Rear

      +£12.99

    • Tau

      Bright enough to blind you when you turn it on so you can be sure that other road users will also see you.

      Tau+ front safety light offers 65 lumens of 270° ultra wide lighting with 10 m beam distance.

      Tau- rear safety light will shed out 20 lumens of 270° ultra wide lighting from the red COB LED strip

      Tau is visible from up to 100 m and is water resistant so they will happily brighten your way even on the gloomiest of days and is impact resistant from 1 m.

      Switch protection prevents any unwanted battery usage and battery capacity indicator will let you know when the juice is running low.

      Only 22g including the USB rechargeable battery and LED lights that never need replacing will keep you light and bright for years to come!

      Each Tau light comes with a bigger and a smaller strap to fit with most bars/seat posts and if you need it even bigger, just lace the bands together to make a larger loop.

    • Tau Front

      +£12.99

    • Tau

      Bright enough to blind you when you turn it on so you can be sure that other road users will also see you.

      Tau+ front safety light offers 65 lumens of 270° ultra wide lighting with 10 m beam distance.

      Tau- rear safety light will shed out 20 lumens of 270° ultra wide lighting from the red COB LED strip

      Tau is visible from up to 100 m and is water resistant so they will happily brighten your way even on the gloomiest of days and is impact resistant from 1 m.

      Switch protection prevents any unwanted battery usage and battery capacity indicator will let you know when the juice is running low.

      Only 22g including the USB rechargeable battery and LED lights that never need replacing will keep you light and bright for years to come!

      Each Tau light comes with a bigger and a smaller strap to fit with most bars/seat posts and if you need it even bigger, just lace the bands together to make a larger loop.

    • Phase / 400

      +£19.99

    • Phase / 400

      The Phase 400 is our lightweight, yet durable, rechargeable bike light for a midweek evening blast on the bike.

      • 5 lighting modes and a 200m beam distance
      • Versatile: can be attached to handlebar, helmet or cockpit mount
      • Rechargeable Li-ion battery, with micro-USB cable

      Say hello to our sleek, new bike light range: they’re light, durable and rechargeable (and they say hi back). At just 123g, the Phase 400 is the final tool you need to make the most of evening rides. With 400 lumens and >200m beam distance, a Phase bike light will keep you company and confident on your dusk rides.

      The Phase 400 has been made with the roadie in mind: whether you’re on a family ride, a mid-week spin or your daily commute to work, you’re going to need an all-round bike light for the incoming dark evenings. But don’t worry if you end up on a canal path or a gravel track, this rechargeable light will suit you just fine for a short jaunt off-road.

      Flick between 5 lighting modes: high, mid, low, SOS and strobe. The Phase 400 has a maximum battery life of 8 hours and 20 minutes in low mode, so in the case of a surprise night-time emergency, you’re sorted. The 80-degree beam angle ensures you can see and be seen.

      We’ve added in some nifty features, including memory lighting. The light will remember the most recently used mode and default to it the next time you head out on your bike. The Phase 400 is compatible with a handlebar mount (included), a cockpit mount and a helmet mount. It also conveniently charges with a versatile micro-USB cable.

    • Phase / 800

      +£29.99

    • Phase / 800

      As the Phase 800 is especially designed for easy-going gravel paths, canals, and short singletrack trails, it is perfectly suited to the gravel rider. The 85-degree beam angle means you can see the journey ahead, as well as be seen by oncoming traffic or the local gravel gang. 

      • >200m beam distance for dusk riding
      • Up to 18 hours of battery life
      • Memory lighting: the light defaults to the most recently used mode upon restarting

      The light boasts 5 modes: high, mid, low, pulse and strobe. In high mode, the Phase 800 lasts 1hr20mins – just enough time for your local mid-week, pre-dinner loop. On the other end of the scale, the 100-lumen pulse mode lasts over 18 hours! No matter your journey, Phase 800 can adapt to your trail.

      It’s got good memory too: the Phase 800 remembers your most recently used mode and defaults to it the next time you turn it on. Once you’ve finished shredding up the local gravel, don’t forget to recharge your light. It just needs a handy micro-USB cable to be ready for when you’re next raring to ride.

    • Hadron

      +£69.99

    • Hadron

      At a whopping 1,800 lumens, the Hadron shines like two twin suns on the front of your bars, allowing you to ride at daytime speeds long after the light fails.

      • Max power of 1,800 lumens with a wide beam angle
      • 6 different lighting modes to tailor to your riding
      • Remote control for swapping between modes at speed

      The Hadron uses twin Cree LEDs to provide a wide, bright beam that stretches well over 200m. This provides a ridiculous amount of night-time visibility so you can tackle tight and twisty singletrack at speed. It also comes with an optional remote control, allowing you to easily swap between lighting modes without needing to take your hands off the brake levers.


      With 6 different lighting modes, the Hadron’s brightness can be effectively tailored to your ride length, terrain and light levels. The lowest brightness Pulse mode runs for a massive 50 hours If you need to save battery on the roads or smoother sections. Plus, the twin bulbs are much more energy efficient than single bulb set-ups.


      The Hadron is housed in a durable 6063 alloy casing to protect your light from crash damage and an IPX6 rating is sufficiently waterproof for all-weather riding. An output jack on the Hadron means you can also use its large 6,700mAh lithium ion battery to charge your GPS or phone if you find yourself out of juice on mid-trip.

    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.

Initial Price
£849
Frame
Frontier SX Eagle Rigid
Size
Colour
Extras
£0
Total Price
£849
Description

Frontier is our multi-activity hardtail mountain bike. Ride hard at the trail centre, load it up for a midweek bikepacking trip, pocket your passport and continue around the world. With full rack mounts at the back and multiple boss mounts on the fork, Frontier is an adaptable off-road explorer.

The geometry is for long day comfort but it’s no slouch.

..Read more

At a glance

  • SRAM SX Eagle 12-speed groupset
  • Frontier Rigid fork
  • Sonder Nova 29" wheelset
  • 6061 aluminium frame

The 6061 aluminium frame provides a durable and stiff chassis giving a responsive kick as you demand power when the slope steepens or enjoy feedback and precision through the corners.

Available as a fully rigid or with 100mm suspension fork. Set it up for XC race speed or for all day big mile comfort.

Tyre clearance gives you the choice of 27.5+ or 29in wheelsets. Bolt through 148mm boost rear spacing provides the benefit of stronger, stiffer and more efficient wheels.

Why SX Eagle?

SRAM Eagle drivetrains are designed, engineered and manufactured to work as complete drivetrain systems. Its 1x drivetrain is built to be lightweight, strong and intuitive, with the gear range to ride on any terrain.

SX Eagle provides the same Eagle performance benefits as NX Eagle, but at a lower price point. The main differences stem from the choice of materials and finish options, but functionally SX is fully compatible with SRAMs Eagle groupset.

Read less
Features

Tuned for all-round capability

Built for a balance of cross country efficiency and trail centre capability. A favourite with bikepackers looking for all-day comfort and performance.

Light and clean

Clean lines thanks to internal cable routing. Frontier also incorporates routing for a dropper seat post. The 6061 aluminium tubing is durable, light, low maintenance and stiff.

Wider tyres. More grip.

Extra width between the chainstays gives you the choice of running 27.5+ tyres up to 3 inches or 29 inch tyres up to 2.5 inches.

Made for stronger wheels

Designed around bolt through Boost 148mm rear spacing providing the benefit of stronger, stiffer and more efficient wheels.

Wilderness trail features

Chainstay mounted disc brakes. And triple bottle mounts.

Build Spec
Frameset
Frame:Frontier Frame / 6061 aluminium
Fork:Frontier Rigid / aluminium
Headset:FSA Orbit C-40-ACB
Groupset
Shifters:SRAM SX Eagle trigger / 1x / 12-speed / hydraulic
Brakes:SRAM Level / hydraulic / direct mount
Rotors:Avid Centreline / 180mm (front); 160mm (rear) / 6-bolt
Rear derailleur:SRAM SX Eagle / 12-speed / long cage
Chainset:SRAM SX Eagle Powerspline / 170mm / 32t
Cassette:SRAM PG1230 / 12-speed / 11-50t
Chain:SRAM NX Eagle / 12-speed
Bottom bracket:SRAM Powerspline / BSA-threaded / 73mm
Wheelset
Wheels:Sonder Nova 29"
Tyres:WTB Ranger / Comp / 29 x 2.4"
Tubes:WTB Inner Tube / 29 x 1.9-2.3"
Finishing kit
Handlebars:Sonder Aspect Riser
Stem:Sonder Piskie
Seatpost:Sonder Seatpost / 31.6mm
Saddle:Sonder Abode
Grips:Sonder Clutch
Weight
Frame:S: 1.97kg; M: 2.0kg; L: 2.1kg; XL: 2.14kg
Build:S: 12.4kg; M: 12.65kg; L: 13.8kg; XL: 13.9kg
Pedals not included with full builds
Geometry and Sizing

Sizing

It is important to get the right size bike, if the bike fits you well it will be faster, more comfortable and easier to handle.

Generally we recommend:
Small: Riders between 5ft 2in and 5ft 7in
Medium: Riders between 5ft 6in and 5ft 10in
Large: Riders between 5ft 9in and 6ft 2in
X-Large: Riders 6ft 2in and over

Size Small Medium Large X-Large
ST - Seat tube 380 430 480 520
TT - Top tube 566 602 622 647
HT - Head tube 110 130 130 150
HA - Head angle 68 68 68 68
SA - Seat angle 73 73 73 73
CS - Chainstay 445 445 445 445
BB - BB drop 50 50 50 50
FO - Fork offset 51 51 51 51
WB - Wheelbase 1089 1127 1147 1174.5
SO - Stand over 764 793 825 853
RE - Reach 390 420 440 460
SK - Stack 566 580 594 613
Frame Spec
Frame Weight: S: 1.84kg; M: 1.9kg; L: 1.98kg; XL: 2.03kg
Rigid Fork Weight - uncut: 1kg
6061 Aluminium frame
Optimised for rigid or 100mm suspension forks
Internal cable routing through downtube
Bolt Through Boost 148mm rear spacing for wheel strength and optimal chainline
Fork built around Bolt Through Boost 110mm spacing
Threaded 73mm BSA BB shell for no-creak assembly
Chainstay mounted disc brake for clean lines and damage protection
Triple bottle cage mount on downtube
Use a seat clamp with integrated mounts for pannier rack compatibility 
Clearance for 3 inch 27.5+ or 2.5 inch 29er tyres
Reverb Stealth port
EN 14766 compliant
Reviews
Kudos
A First Look at the Sonder Frontier

It is a bike that will likely tick many boxes for anyone planning multi-day rides, without first returning home for their tea.

Read the full review here.

Author: Bearbonesnorm
Active Traveller Review the Sonder Frontier

This cracking value and rock solid machine from Sonder is just crying out to be loaded up and taken to the horizon.

Read the full review here.

Author: Andy McCandlish
Cycling Life Review the Sonder Frontier

Giving several centimeters of squish, their suspension-like characteristics help the Frontier float over rough terrain. With big handlebars, an upright position, and loads of stand-over, the Frontier is great for roistering about on, and could certainly serve as a regular mountain bike.

Read the full review here.

Author: CyclingLife
Frontier - Tried and Tested

The Frontier might be considered a Jack of all trades but the clever bit is, it's able to master most of them.

Read the full review here.

Author: Bearbonesnorm