Our site works best with JavaScript enabled.

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.

£1099.00 Was: £1099.00
List Price: £1249.00

Available on finance, from per month*

Pictures shown are for illustration purpose only. Actual products may vary due to stock availability at time of purchase (for example tyres, saddles, handle bars). Please refer to the build spec before purchase.

  • 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


'Buy now' means the build and size is available - you can buy it now!
'Sold out' - we're out of stock and don't currently have an ETA - we'll update the chart as soon as we do.
'Building / Shipped from' you can order now but your bike frame/components will be arriving in Neil’s workshop on the date given. Your bike should be shipped from HQ within 15 working days of this date.

Build option Small Medium Large X-Large
Chilli Buy Now! Buy Now! Buy Now! Buy Now!
Nemo Buy Now! Buy Now! Buy Now! Buy Now!
Stirling Moss Buy Now! Buy Now! Buy Now! Buy Now!

Choose your Sonder from these options:

  • Frontier Frame

Please allow 15 working days for your bike to be built, checked and despatched.

Alternative payment options

Guide to paying with Cycle to Work Schemes

Close Brothers Logo
Spread the cost of your purchase show details...
Finance Option
Item Price
Order Administration Fee
Purchase Price
Deposit to Pay
Amount of Credit
Finance Term
Monthly Payments
Total Amount Payable
APR Representative
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

About this build

When the hills get bigger, the rocks get squarer and the terrain bites back.

The days when more gears were considered better are long gone. SRAMs NX1 drivetrain delivers a wide range of gear choices in a 1 x 11 package engineered for simplicity and durability. Don’t worry about dropping a chainring up front, the 1 x 11 gearing gives a 2.9 - 0.8 ratio (82.9 - 21.7 gear inches with 2.8” tyre). That’s plenty of range to tackle steep technical climbs, select your optimum pace on long slogs and open up on the descents.

Traction is delivered in bucket loads by our Love Mud Rumpus 650b+ Boost wheelset. The new ‘Plus’ sizing standard gives you all the benefits of a fat bike without any of the negatives. They roll just as fast as your regular tyre, have more grip and thanks to the lower tyre pressures are nice and comfortable. Our Rumpus 650b+ rim has an internal width of 45 mm and is ideally suited to 2.8 – 3.5” tyres. The rims can also be setup tubeless with the use of some 45 mm tape and a compatible tyre.

Our choice build for technical mountain exploration.

Frontier DNA

Frontier is our multi-activity hardtail mountain bike - ride it hard around the trail centre, load it up and sneak off for a midweek bikepacking trip through mid-Wales, pocket your passport and continue around the world.

The geometry is relaxed for long day comfort but its 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.

Frontier can be tailored to ride how you want it to ride. If fully rigid is not for you the geometry and head angle allows capacity to take a 100 mm fork. So you can have it set up for XC race speed or all day plod comfort and put in the miles. Big 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.

Optimised for 1x drivetrains, Frontier is available in NX1 builds with rigid or suspension forks.

Frontier excels both loaded and unloaded, absorbing every surface you ride - you decide how you want to pack for your adventure. With full rack mounts at the back and multiple boss mounts on the fork Frontier is an adaptable offroad explorer. Responsive when loaded up in the modern lightweight bikepacking style of travel, it is more than happy for a set of panniers to be thrown over it.

Wherever you are in the world - squeezing in an afterwork loop or halfway through an adventure of a lifetime; Frontier eats up long distance trails with style and comfort with the shameless enthusiasm of a trail centre hardtail.

Internal cable routing

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

Aluminium frame

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

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


You can swap some Love Mud components on this build at no additional cost (as long as we have the stock). So if you know what length of stem you need, a particular saddle or bar then let us know in the notes section in the checkout and we will let you know if this is possible.

Common Upgrades

We hold big stocks of SRAM groupsets and components, Rockshox forks and can build with Shimano, Hope and almost any part for you. Give us a call and we will help spec and build a Sonder. 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

Our titanium frames are handmade and come with a 10 year frame warranty. 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.



1 Reviews


Used this product?

Write a review
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.