Arctodus
BUILT FOR WINTER EXPLORing
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. When a bike is created for big rides with fresh snow, it needs to fit tires that were designed for the same reason. 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. This frame is also compatible with Wolf Tooth GeoShift 1º and 2º Angle Headsets, effectively unlocking five head tube angles from 66.5º to 70.5º. 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.
AND SO MUCH MORE ...
NARROW Q FACTOR
Arctodus has a 100mm bottom bracket. This is 30-40mm narrower than other fat bikes that have the same tire clearance. Ride with massive tires without compromising handling.
SUSPENSION CORRECT
All Otso frames feature suspension-corrected geometry. Arctodus is compatible with suspension forks that have up to 120mm of travel. A few options are available on the Custom Bike Builder.
STABILITY & FLOATATION
Arctodus geometry was designed for optimal riding on fresh trails. The 68º head tube angle paired with massive tires gives Arctodus more trail than other fat bikes.
DROPPER COMPATIBLE
Snowy trails are good with dropper posts, too. A port near the bottom bracket fits a cable and housing or hydraulic hose for dropper posts that require internal frame routing.
TECHNICAL DETAILS
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Base Build
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Frame Specs
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Geometry
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Racks & Fenders
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 (rear hub offset 5mm) |
Tires | Terrene Johnny 5 Light 26"x4.8" |
Chain | Shimano SLX 12-speed |
Frame Sizes | S, M, L, XL |
Bottom bracket standard | 100mm BSA threaded |
Q-factor | 205mm with Race Face Aeffect crankset |
Maximum chainring size | 36T round or 34T oval |
Front derailleur type | None. 1x only bike. |
Headset | ZS44 upper, EC44 lower |
Seatpost diameter | Ø31.6mm, accommodates internally routed dropper post |
Seatpost clamp | Ø34.9mm |
Front/rear hub standard | 150x15mm thru axle / 197x12mm thru axle offset 5mm to drive side (rear wheel must be dished 5mm) |
Front/rear axle | Ø15x150mm, TP=1.5, TL=12mm / Ø12x235mm, TP=1.5, TL=14mm |
Rear Dropouts | Tuning Chip Dropout with adjustable chainstay length, offset 5mm |
Derailleur hanger | Tuning Chip Right Dropout |
Rear brake (rotor) | 74mm post (160mm native, 180mm max) |
Front brake (rotor) | 74mm post (160mm native, 180mm max) |
Fork axle-to-crown | 485mm, suspension corrected for 100-120mm travel forks |
Fork offset | 51mm |
Bare frame weight (size M) | 3410g |
Fork weight (Otso rigid fork) | 650g |
Tire clearance (frame) | Up to 26"x5.25" or 27.5"x4.5" or 29"x3" in all Tuning Chip positions |
Tire clearance (fork) | Up to 26"x5.4" on 100mm rim |
120mm fork note | Using a 120mm suspension fork with slacken the head tube angle by 0.5˚ |
Frame Bag Dimensions | Small Medium Large X-Large |
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 |
Compatible fenders
PDW - Mud Shovel Front and Rear Fenders
SKS - Fatboard Fender Set
compatible racks
Salsa - Alternator Rear Rack 190 / 197
Topeak - Uni Super Tourist Fat Rear Rack
Blackburn - Outpost Fat Rear Rack
Surly - Rear Disc Rack Wide
Frame Bag Dimensions
(click on links to view PDF drawings)
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