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Sonder Frontier NX1 Reba Rumpus 650b+

Quick, lightweight 650b+ modern mountain bike with SRAM NX1 1 x 11 groupset, Reba fork and Love Mud Rumpus wheelset.

List Price: £1299.00

Available on finance, from per month*

Pictures are for illustration and some components and finishing kit of this build may be different. Please refer to the detailed spec sheet before placing an order.

  • Sonder Frontier NX1 Reba Rumpus 650b+ Chilli - Chilli
  • Sonder Frontier NX1 Reba Rumpus 650b+ Stirling Moss - Stirling Moss
    Stirling Moss
  • Sonder Frontier NX1 Reba Rumpus 650b+ Nemo - Nemo

This Sonder is available for Pre-Order

How To Order

All our bikes are built individually to order. If you want to change any part of the spec to suit your needs then get in touch.

  • Frontier Frame

  • 1. Select Size

    Please select a size. See the fitting guide for size information

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    Stirling Moss

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We act as a credit broker and not a lender and can introduce you to Close Brothers Retail Finance. Terms and Conditions apply. Finance subject to status. Applicants must be 18 or over and resident in the UK. Finance provided by Close Brothers Retail Finance, a trading style of Close Brothers Limited – a subsidiary of Close Brothers Group Plc. Registered Office: 10 Crown Place, London, EC2A 4FT.
At a glance
  • For searching out technical terrain
  • 6061 aluminium frame
  • Relaxed riding position for comfort and performance
  • Rockshox Reba suspension forks
  • Hydraulic disk brakes
  • QR Boost 141mm rear spacing
  • Rear mudguard and pannier rack mounts
  • 650b+ and 29” wheel size compatible frame

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.

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 100 mm 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. QR Boost 141 mm rear spacing provide the benefit of stronger, stiffer and more efficient wheels.

Aluminium frame

The 6061 aluminium tubing is durable, light, low maintenance and stiff.

Internal cable routing

Clean lines and tidy cables thanks to internal routing. Frontier also incorporates routing for a dropper seat post.

Wide tyre clearance

Extra width between the chainstays gives you the choice of running 27.5+ tyres up to 3 inches or 29 inch tyres up to 2.4 inches.

Boost axle width

The Frontier frame is designed around QR Boost 141 mm rear spacing providing the benefit of stronger, stiffer and more efficient wheels. Seatstay mounted disc brake for clean lines and damage protection.

Pannier ready

Responsive when loaded - Frontier is more than happy to shoulder a pannier.

Frame spec

Frame Weight (kg): S: 1.7; M: 1.8; L: 1.86; XL: 2.0
Fork Weight - uncut (kg): 1.0
6061 Aluminium frame
Optimised for rigid or 100 mm suspension forks
Internal cable routing
QR Boost 141 rear spacing for wheel strength and optimal chainline
Fork built around QR Boost 110 mm spacing
Threaded 73 mm BSA BB shell for no-creak assembly
Chainstay mounted disc brake for clean lines and damage protection
Adventure cage compatible downtube mount
Full rack mounts and multiple boss mounts on rigid fork
Clearance for 3 inch 650b+ or 2.5 inch 29er tyres
Reverb Stealth port
EN 14766 compliant

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:

Riders between 5ft 2in and 5ft 7in
Riders between 5ft 6in and 5ft 10in
Riders between 5ft 9in and 6ft 2in
Riders 6ft 2 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 435 435 435 435
BB - BB drop 50 50 50 50
FO - Fork offset 51 51 51 51
WB - Wheelbase 1089 1127 1147 1174.5
SO - Stand over
RE - Reach 390 420 440 460
SK - Stack
Build SRAM NX1, 1 x 11
Frame Sonder Frontier Frame
Fork Reba
Headset Love Mud Rumour, Integrated Sealed Bearing, Tapered
Seat clamp Love Mud Vice, 34.9 mm
Group set
Brake Front SRAM Level 800mm
Brake Rear SRAM Level 1400mm
Rotor Rear Avid Centreline 160 mm
Rotor Front Avid Centreline 180 mm
Rear mech SRAM NX1 Rear Derailleur 1x11 Long Cage
Shifter Rear SRAM NX1 11sp
Chainset SRAM NX1 Chainset 1 x Xsync 32T
Bottom Bracket SRAM GXP
Chain SRAM PC1110 Chain 118 Links
Cassette SRAM PG-1130 11sp
Finishing Kit
Stem Love Mud Piskie, 31.8 mm
Seatpost Love Mud Membar, 31.6 mm
Saddle Love Mud Abode
Tape/Grips Love Mud Grabby
Handlebar Love Mud Aspect Riser, 780 mm
Wheels Love Mud Rumpus 650b+ Wheelset
Tyres WTB Ranger 2.8 Comp
Tubes WTB Inner Tube Presta 27.5, 2.8-3.00
Frame S: 1.7 kg; M: 1.8 kg; L: 1.86 kg; XL: 2 kg
Fork 1.09 kg
Built S: TBC; M: 13.3 kg; L: TBC; XL: TBC
Unfortunately we haven't been able to weigh these bikes yet, please bear with us and we'll update this page as soon as we can
Pedals not included with full builds

Swapouts and Upgrades

You can interchange Love Mud components on this build at no additional cost. So if you want a different length of stem, a particular saddle or bar then let us know in the notes section in the checkout and we'll get in touch. We also hold big stocks of SRAM, Rockshox, WTB and regular build with Shimano, Hope, Cane Creek. We'll build your Sonder with any part that suits your needs. Give us a call, with the same experienced mechanic helping throughout your build you know who to call if there's anything you want to know.

Click here for more information

Alpine Bond Warranty

We offer a 10 year guarantee on both our handmade titanium and Reynolds steel frames. Our hand welded 6061-T6 alloy triple butted frames and carbon frames come with a 5 year manufacturing defect warranty. All our bikes are built, checked and signed off by Cytech trained mechanics before being despatched to you in a custom-made bike box.



2 Reviews


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Rimantas Urnikis
The beast!

Had to wait almost a month for this beauty, but oh boy it was worth it! Plowed through forest tracks with no effort at all. This is my first MTB so I wanted something simple and effective. If you are like me when have a shock pump beforehand because it is not included and you will not be able to set your fork properly. All in all I'm very happy with the purchase. High value, beautiful, comfortable and I can't wait to go on the bikepacking trip with this beast. See you on the trails!

Indestructable Adventure Machine

On Friday 25th May 2018 I completed a 26 day mountain bike ride commencing from Dunnet Head, heading across to John o' Groats, meandering down the country across all manner of landscape to Lands End, before then completing my trip at Lizard Point. I covered more than 1200 miles.

I carried out this mammoth undertaking on a Sonder Frontier Recon Rumpus, purchased just a month before leaving after a brief weekend trial in Wales. Clearly it was an extreme product test and it was a choice I did not regret for one second. The bike was a constant pleasure to ride and held up to everything that was thrown at it, including Scottish Highlands, Yorkshire moors and Welsh hills.

It looks a very different beast from when it arrived at my house only a couple of months ago, bearing scars of bike pack straps across the frame and in need of new tyres, but the only things I had to do on route were replace some very worn brake pads and change one inner tube. The slow puncture I picked up on the last two days would wait until I got home.

Sonder have deliverd a durable, comfortable and reliable machine which transported me without issue. Of all the things I had to tackle on my trip I was very thankful a troublesome bike wasn't one of them.

Simply put, I thoroughly recommend this bike.