• Frontier Frame
  • Frontier Frame
  • Frontier Frame
    • Special Offer

    Frontier Frame

    Multi-activity trail bike

    £339 £399


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    Lightweight alloy hardtail mountain bike frame to build your own 29er or 650b+ bike from trail centre to wild and remote landscapes.
    Buy Now. In stock for same day despatch.


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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.


      Select Accessories



      No Headset
      No Headset


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


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        Frontier Frame / Select a frame...



        Total Price

        Buy Now. In stock for same day despatch.

        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. Frontier is an adaptable off-road explorer.

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

        At a glance
        • 6061 aluminium frame
        • 148mm Boost bolt through rear axle
        • Rear mudguard and pannier rack mounts
        • 650b+ and 29" wheel size compatible 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.


        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.

        Geometry and 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 (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 380 430 480 520
        TT - Top tube 563.1 597.3 621.6 647.3
        HT - Head tube 110 115 130 150
        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 1095.7 1131.3 1157 1184.5
        SO - Stand over 764 793.9 824.6 852.6
        RE - Reach 390 420 440 460
        SK - Stack 566.1 580.1 594 612.5
        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

        • Frontier Frame
        • Frontier Frame
        • Frontier Frame