Sonder Vir Fortis Go full fat. Carbon fat bike for wilder, wider adventures to places no other bike can venture
Sonder Vir Fortis frame and fork
With geometry inspired for the trail, a lightweight carbon fat bike frame and fork bundle for a bike that is as wide as your dreams
Sonder Vir Fortis GX Eagle
Carbon fat bike with SRAM GX Eagle
Go full fat and go where no other bike can. A full carbon fat bike with slack geometry for a fun characterful trail friendly ride. Float over surfaces, or blast local trails on big 4.8” tyres.
Built for exploring and Iditarod capable, Vir Fortis isn't your regular faceless hero.
Hand laid T700 carbon fat bike for rides (and riders) that don't conform to the norm. Guaranteed for 5 years the frame weighs in at 1380g and fork at 650g.
Vir Fortis frame and fork at £850; complete bikes from £1899.
Arrange a demo at one of our stores or test ride over a weekend for £39 a day plus £30 delivery and return shipping.
Compatible with 4.8” tyres, Vir Fortis is set up to get you over the most adventurous terrain. Vir Fortis might not be the bike you ride everyday, but it will be the bike you want to ride everyday!
Geometry with a trail riding pedigree, Vir Fortis positively encourages you to explore the outer limits of your trail and cross country riding. The ultimate expression of this is finding terrain which used to be a no go area for bikes - like snow or sand.
The only thing wider than the grin on your face will be your tyres - and that’s as it should be. Go nice places regular bikes can’t go. Bigger tyres equals bigger adventures.
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.
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
Frame Weight: S: 1475 g; M: 1550 g; L: 1595 g
Fork Weight: 650 g
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|
All our bikes are built in-house, checked and signed off by Cytech trained mechanics before being despatched to you in a custom-made bike box.
- Are Sonder available outside the UK?
- What are builds and groupsets?
- Common Bike Upgrades: price list
- Why have Alpkit designed their own bikes?
- Which wheelset for which Sonder Bike?
- Try Before Your Buy - Sonder Demo Bikes
- How much does international shipping for Sonder Bikes and Love Mud Wheels cost?
- Cycle to Work Schemes
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 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.
Explore other content related to Sonder Adventure Bikes on our site.
Doing the Dempster: Arctic Fat Biking
Mark Hines Fat Biking in the Arctic
Preparing for Rovaniemi 150
Steve Bate fat biking in the Arctic circle
Cold. Brutal. Epic.
Braving the ice to take on the ‘Puffer
A Winter’s Training Tale Part 1
Hero training with the Sonder Gurus
Sonder Evol: Q&A with Bike Guru Neil
Sonder's new 140mm trail bike
Blindly Seeking Sunshine… and Zeus…
Bikepacking the Greek Isles
Biking in the Blood
Back in Black
Returning to the Dark Side
A Bike Ride through Romania
Cycling the Faroes
Island hopping up North
Ultralight bikepacking through Norway
Valleys, fjords, and phenomenal tarmac
Ride Across Britain
Fat Biking LeJog