Sonder Vir Fortis SX Eagle
Carbon fat bike with SRAM SX Eagle
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.
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.
Vir Fortis frame and fork
Please allow 20 working days for us to build, check, pack and despatch your Sonder.
Alternative payment options
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|Alpkit Ltd acts as a credit intermediary and offer credit products provided exclusively by Klarna Bank AB (publ). Klarna Bank AB (publ) is Authorised by the Swedish Financial Services Authority (Finansinspektionen) and is subject to limited regulation by the Financial Conduct Authority. Details about the extent of our regulation by the Financial Conduct Authority are available from us on request. Finance is only available to permanent UK residents aged >18, subject to status, terms and conditions apply. Registered office: Sveavägen 46, 111 34 Stockholm, Sweden. Corporation ID number: 556737-0431.|
When you want to go places a regular skinny bike won’t, go you need a hero. Enter Vir Fortis, a bike made for terrain that may never have been navigated on two wheels, crushing turnips, or for just in case you get snowed in and need to save the neighbourhood.
At a glance
- Fat, light, and comfy for wilderness exploration
- Frame: Sonder Vir Fortis, high grade T700 carbon
- Drivetrain: SRAM SX Eagle
- Fork: Vir Fortis, high grade T700 carbon
- Seatpost: Love Mud Membar, 31.6 mm
- Wheelset: Love Mud Hurlyburly
- Tyres: Vee Rubber Bulldozer 4.25
Vir Fortis is designed to go anywhere, big tyres and big wheels gives a massive amount of traction.
Vir Fortis is not just strong, it is light too: a medium frame weighing in at just 1550g and letting you float over the wildest trails like a cloud. It looks sharp: cables are routed internally to avoid snagging and keep things clean, and a single mounting point on the downtube gives you the option to add a bottle cage.
With a race-winning pedigree, Vir Fortis inspires you to explore the outer boundaries of the trails. Its slackened off geometry gives a characterful ride and is compatible with tyres up to a chunky 4.8”. It’s carbon frame and fork gives precise handling and trail bike feel.
It has taken on some of the roughest rides in the wildest terrain, and come out on top.
Hand laid carbon fibre frame and fork
Using Toray’s highest grade of carbon, T700, this frame is manufactured in a clinical environment to the highest standards. The result is an extremely strong, lightweight frame that is a blast to ride! Guaranteed for 5 years
Trail bike inspired geometry
The Vir Fortis take fun to the next level by slackening the bike out a bit, giving it a more relaxed, playful character. With natural air suspension from the enormous tyre volume Vir Fortis is ready to roll over all terrains.
Internally tapered head tube
Who would choose to be a head tube? You might as well step into the ring with Mike Tyson. It is a critical junction point where forces are distributed around the frame and steering precision is won or lost. Vir Fortis uses a fully integrated internal headset and a fork with a tapered carbon steerer tube to make sure you hold your line over broken ground.
Disk brake compatible
Once rolling you will be surprised by how you can carry your momentum which is why you are going to be thankful for the stopping power of disc brakes. The Vir Fortis carbon frame is fully compatible with disc brakes.
High spec builds
If you’ve a dream build in mind, please get in touch and we’ll do our best to source the parts you want.
Carbon is the most versatile material for building a bike frame, not only can you mold it to look exactly how you want, you can also layer it up differently to affect the ride characteristics. This allows us to build frames that are stiff in the areas they need to be and have the right amount of compliance in others making for an incredibly lively but comfortable ride.
|Frame Weight (kg): S: TBC; M: TBC; L: TBC|
|Fork Weight - uncut: TBC|
|Toray T700 carbon fibre|
|Headset: IS42/28.6 | IS52/40|
|Seat post: 31.6 mm|
|Seat tube OD: 34.9 mm|
|100mm BSA BB shell|
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:
Riders between 5ft 2in and 5ft 7in
Riders between 5ft 6in and 5ft 10in
Riders between 5ft 9in and 6ft 2in
|ST - Seat tube||406||457||505|
|TT - Top tube||580||605||625|
|HT - Head tube||100||110||130|
|HA - Head angle||68.5||68.5||68.5|
|SA - Seat angle||73.5||73||73|
|CS - Chainstay||445||445||445|
|BB - BB drop||60||60||60|
|FO - Fork offset||45||45||45|
|WB - Wheelbase||1103||1123||1145|
|SO - Stand over|
|RE - Reach||406||423||437|
|SK - Stack||586||595||614|
|Build||SRAM SX Eagle, 1 x 12|
|Frame||Vir Fortis Carbon|
|Fork||Vir Fortis Carbon|
|Headset||FSA Orbit C-40-ACB|
|Seat clamp||Love Mud Silent Partner, 34.9 mm|
|Brake Front||SRAM Level|
|Brake Rear||SRAM Level|
|Rotor Front||Avid Centreline 180 mm|
|Rotor Rear||Avid Centreline 160 mm|
|Rear Mech||SRAM SX Eagle|
|Shifter Rear||SRAM SX Eagle|
|Chainset||SRAM NX Eagle Fat, 170 mm, 30T|
|Bottom Bracket||SRAM DUB|
|Chain||SRAM NX Eagle|
|Cassette||SRAM PG1230 Eagle 11-50t|
|Stem||Love Mud Piskie, 31.8 mm / 55 mm|
|Seatpost||Love Mud Membar, 31.6 mm / 400 mm|
|Saddle||Love Mud Abode|
|Tape/Grips||Love Mud Clutch|
|Handlebar||Love Mud Aspect Riser, 740 mm wide|
|Spacers||Love Mud (3x10 mm, 1x5 mm)|
|Wheels||Love Mud Hurlyburly|
|Tyres||Vee Rubber Bulldozer 26” 4.25”|
|Tubes||Vee Inner Tube|
|Frame||S: TBC kg; M: TBC kg; L: TBC kg; XL: TBC kg|
|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.
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.