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Otso Arctodus
Big adventures require a bike that can rise to the occasion. Arctodus is named after Arctodus simus, an Ice Age behemoth that was the largest bear to ever walk the Earth. Like its namesake, Arctodus the bike is versatile, strong, and ready to explore. It has adjustable geometry, a durable steel frame, a massive front triangle for a frame bag, lots of cargo mounts, and can clear the biggest fat bike tires on the market. Arctodus is ready for afternoon exploration, polar expeditions, and everything in between.
We have customized the Arctodus to have PURPLE seatpost clamps, headsets, headset spacers, and bolts from Wolf Tooth for that extra splash of colour to match the OTSO logo on the downtube.

THE BIGGEST TIRE CLEARANCE
Arctodus was built around a 26″ x 4.8″ tire for optimal handling and control on loose trails. It can fit the biggest fat bike tires in the world. The biggest fat tire on the market is 26″ x 5.05″ and Arctodus eats them like a snack with room to spare. Same as 27.5″ x 4.5″, which is the biggest 27.5″ tire available. Arctodus is the only bike to clear tires this big with a 12-speed drivetrain without chain interference. This is a bike that prays for snow and cuts its own trail.


ADJUSTABLE GEOMETRY
A key feature in all Otso bikes is adjustable geometry and the ability to adapt the bike for the ride ahead. The patented Tuning Chip rear dropout system can change wheelbase length by up to 20mm, raise or lower the bottom bracket height by up to 4mm, and change the head tube angle by +/- 0.5º. Use the rear position when the trails are loose and you need as much control as you can get. Use the front position when the snow is firm and the trails let you take turns with a little speed. No matter the conditions, Arctodus has an answer.
DESIGNED FOR EXPLORING
There’s no need to wait for the trail groomer. Arctodus was made for foot trails, forest paths, and snow-covered frozen lakes. The bombproof steel frame can withstand the demands of an expedition. A large front triangle can fit a healthy full frame bag. The carbon fork has mounts on either side for cargo. A rear rack can be attached via mounts on the seat stays. Even the geometry is catered for exploration, with extra trail for optimal flotation and bottom bracket height that’s friendly with deep snow. Whether you’re exploring local trails or a national forest, you can trust Arctodus to keep you riding.

Build Kit
Frame | Chromoly with Tuning Chip™ dropout system |
Fork | Lithic carbon fat fork, suspension corrected, tapered steerer tube, 485mm axle-to-crown, 51mm offset |
Headset | Wolf Tooth Performance Headset, ZS44/EC44 |
Rear derailleur | Shimano SLX M7100, 12-speed |
Front derailleur | None, 1x only bike |
Shifters | Shimano SLX M7100 Trigger, 12-speed |
Cassette | Shimano SLX M7100, 10-51t, 12-speed |
Brakes | Magura MT4 |
Cranks | Race Face Aeffect with Wolf Tooth CAMO System P2 (+4mm offset) spider, 30T chainring |
Bottom bracket | Race Face, BSA 100mm |
Handlebar | Race Face Ride, 740mm riser |
Grips | Wolf Tooth grips |
Stem | Aluminum |
Seatpost | Aluminum, 31.6mm |
Seat | WTB Volt Medium, 142mm width |
Wheels | Lithic Rhyolite 90 26″ 84mm with Lithic Hubs |
Tires | Terrene Johnny 5 Light 26″x4.8″ |
Chain | Shimano SLX 12-speed |
Frame Sizes | S, M, L, XL |
Upgrade Options
Tires – We have the largest selection of Fat Bike Tires in Canada and know the best to spec for each type of rider and condition. Our on-site trail system allows us to test each tire on multiple rims and pressures right out our door in a variety of snow conditions (We’re located in the Snow Belt!). We offer tires from Terrene, 45NRTH, Maxxis, and Surly.
Brakes – Not every rider prefers the brake spec of every stock build so if you want better stopping power out of the box on your build we offer a good selection of brake upgrades from SRAM, Shimano and Hope to swap into your bike build.
Wheelsets – Custom fat bike wheels are our specialty and 100’s of sets have run through our local wheel builders hands. On any build you can opt for a custom wheelset from our selection of rims from Foundation (our in house carbon), HED, Lithic, Stan’s and hubs from Hope, DT Swiss, Onyx and Industry Nine.
Cockpit – Personalizing your build comes down to the cockpit and ensuring it fits you best. These are your touch points and also a great way to personalize your ride. We offer a large selection and colors in handlebars, stems, seatposts (dropper options), saddles, grips and right down to the pedals. Why settle for off the shelf when you can have your bike built the way you want it with parts from your authorized dealer for Raceface, Chromag, PNW, OneUp and many more!
Bags & Racking – We also offer a wide selection of racks and bike packing accessories from EVOC, Salsa, Relevate Designs, PRO and More with special order color and custom frame bag options!
Give us a call for details.

Frame Size | Small | Medium | Large | X-Large |
Recommended rider height | 4’9″-5’5″ | 5’5″-5’9″ | 5’9″-6’1″ | 6’1″-6’7″ |
Recommended rider inseam | 29″-32″ | 31″-33″ | 32″-35″ | 34″-37″ |
Effective top tube | 589mm | 610mm | 632mm | 657mm |
Nominal head tube angle | 68.5° | 68.5° | 68.5° | 68.5° |
Tuning Chip induced head/seat tube angle change | ±0.2° | ±0.2° | ±0.2° | ±0.2° |
Head tube length | 90mm | 90mm | 100mm | 120mm |
Nominal seat tube angle | 74° | 74° | 74° | 74° |
Seat tube length | 380mm | 420mm | 465mm | 510mm |
Bottom bracket drop | 80mm | 80mm | 80mm | 80mm |
Chainstay length | 440-460mm | 440-460mm | 440-460mm | 440-460mm |
Wheelbase | 1119-1139mm | 1140-1160mm | 1162-1182mm | 1189-1209mm |
Trail | 94mm | 94mm | 94mm | 94mm |
Fork offset | 51mm | 51mm | 51mm | 51mm |
Rigid fork axle to crown length | 485mm | 485mm | 485mm | 485mm |
Stack | 607mm | 607mm | 617mm | 635mm |
Reach | 415mm | 435mm | 455mm | 475mm |
Standover | 707mm | 736mm | 773mm | 810mm |
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