The Otso Fenrir is a ride-anywhere bike for bikepacking races and afternoon adventures alike. It can be built with drop bars or with MTB bars and both selections are available as stock build options. A tire clearance of 29” x 2.8” or 27.5” x 3.0” keeps the Fenrir rolling on rough terrain, while extra frame and fork braze-ons are ready to carry gear for days or weeks on the trail. Like all Otso bikes, the Fenrir has adjustable geometry via the patented Tuning Chip rear dropout system that makes the bike as adaptable as its rider.
Fenrir Stainless
RIDE ANYWHERE
VERSATILITY
While all Otso bikes are known for their versatility, the Fenrir might be the most versatile yet. It was designed to accommodate drop bars with a 50mm stem or MTB bars with an 80mm stem. It can be built with gears or single speed, with a suspension fork or rigid, with a mechanical or electronic drivetrain, or with a dropper or rigid seat post. The ability to fully customize the build of the bike makes the Fenrir as versatile as its rider.
FENRIR WITH DROP BARS
The Fenrir was designed with the option to be built with drop bars or MTB bars. When configured with drop bars, the Fenrir rides like an extra-capable gravel bike. The relatively longer top tube means a shorter stem is needed with drop bars to align with the rider's preferred reach. It can be built with standard road/CX/gravel bars for rides on local trails or with wider bars to fit a handlebar roll loaded with lots of gear.
FENRIR WITH FLAT BARS
When built with MTB bars, Fenrir rides like a 90s XC bike. It's fun and lively, yet efficient and Capable with a capital C. It can handle any sketchy descent or technical climb with ease. Because the top tube is relatively short for a mountain bike, a longer stem (80-90mm) is ideal for maintaining reach. Ride it on your local singletrack or load 'er up for that backcountry tour that you've been dreaming about--you know the one. However you choose to build it, Fenrir will ride any road/trail on the map and carry all the gear to get you there.
OPTIMIZED FOR BIKEPACKING
Every last feature of Fenrir is optimized for bikepacking. The stainless steel frame is strong, comfortable, and surprisingly light weight. It can be built with flat bars or drop bars depending on your affinity for large handlebar rolls. Single speed is an option for folks who like simplicity while touring. It has extra mounts on the frame and fork for hauling all the gear you'll need for days (or weeks) on the trail. The frame and fork can clear 29" x 2.8" or 27.5" x 3.0" tires for trails that are especially gnarly. No matter your destination and how long it takes to get there, Fenrir is ready.
SINGLE SPEED
All metal Otso bikes have the option to be built single speed or with gears. Fenrir is included in that group because it has a small notch on the rear dropout near the Tuning Chip. If you build your Fenrir with gears, but want to convert to single speed later on, we have the single speed Tuning Chip available on our website alongside other accessories. There's no wrong way to build your Fenrir.
AND SO MUCH MORE ...
SO MANY MOUNTS
A bikepacking bike needs to be able to carry all the gear for days or weeks on the trail. Fenrir has mounts for bottles, fenders, and racks. The Enve fork also has three-pack mounts on either side for sharing the load.
CAPABLE GEOMETRY
Pick a trail on the map and ride it. Fenrir has the endurance of a gravel bike, with the stability of a mountain bike. Above all, it is Capable with a capital C so you can stay the course and reach your destination.
DROPPER FRIENDLY
A small port near the bottom of the seat tube allows for the cable routing of a dropper post. If you don't ride with a dropper, you probably won't even notice the port.
AMPLE CLEARANCE
Tires need to meet demands of the trail for traction, stability, and comfort. Fenrir can ride up to 29" x 2.8" or 27.5" x 3.0" tires.
TECHNICAL DETAILS
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Base Build
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Frame Specs
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Geometry
| DROP BAR | FLAT BAR | |
|---|---|---|
| Frame | Custom butted austenitic stainless steel frame | Custom butted austenitic stainless steel frame |
| Fork | Carbon Enve Mountain Fork, 15mm thru axle | Carbon Enve Mountain Fork, 15mm thru axle |
| Headset | Wolf Tooth Performance Headset | Wolf Tooth Performance Headset |
| Rear derailleur | Shimano GRX 810, 11-speed | TRP G-Spec TR12, 12-speed |
| Front derailleur | N/A | N/A |
| Shifters | Shimano GRX 600, 11-speed | TRP G-Spec TR12, 12-speed |
| Cassette | Shimano SLX, 11-46T, 11-speed | SRAM GX, 10-51T, 12-speed |
| Brakes | Shimano GRX 600 hydraulic | Magura MT4 hydraulic |
| Cranks | Race Face Aeffect | Race Face Aeffect |
| Handlebar | Lithic Corundum aluminum compact drop with 16° flare | Lithic flat bar |
| Tape / Grips | Wolf Tooth Supple Lite Bar Tape | Wolf Tooth silicone foam grips |
| Wheels | Sun Ringle Duroc 30 | Sun Ringle Duroc 30 |
| Tires | Maxxis Aspen 29" x 2.4" | Maxxis Aspen 29" x 2.4" |
| Frame Sizes | XS, S, M, L, XL | XS, S, M, L, XL |
| Bottom bracket standard | Shimano english thread BSA, Ø73mm |
| Maximum chainring size | 1x: 40T round or 38T oval |
| Front derailleur type | N/A |
| Headset | ZS44/28.6 upper, EC44/40.0 lower |
| Seatpost diameter | Ø31.6mm |
| Internal dropper post routing | Yes. Exit port on bottom of seat tube |
| Seatpost clamp | Ø34.9mm |
| Front/rear hub standard | 110x15mm thru axle / 148x12mm thru axle |
| Front/rear axle | Ø15x100mm front, TP=1.5, TL=15mm / Ø12x187mm rear, TP=1.5, TL=12mm |
| Derailleur hanger | Wolf Tooth Tuning Chip Right Dropout |
| Rear brake (rotor) | Flat mount, 74mm post mount available(160mm) |
| Front brake (rotor) | Post mount native,(160mm post mount or 180mm flat mount) |
| Fork axle-to-crown | 490mm (suspension corrected for 100mm suspension fork) |
| Fork offset | 44mm or 52mm |
| Bare frame weight (L) | 5.7lbs (2580g) |
| Fork weight (Enve rigid fork) | 676g |
| Tire clearance (frame) | 2.3" at 420mm chainstay position, 2.6" at 430mm, 27.5" x 3.0" or 29" x 2.8" at 440mm |
| Tire clearance (fork) | Max clearance 29" x 2.8" or 27.5" x 3.0" |
| Braze-ons | 3 bottle mounts, fender, rack, cable clamps |
| Frame Bag Dimensions | X-Small Small Medium Large X-Large |
| XS | S | M | L | XL | |
|---|---|---|---|---|---|
| Recommended rider height | 4'10"-5'4" | 5'3"-5'7" | 5'7"-5'11" | 5'11"-6'3" | 6'3"-6'6" |
| Effective top tube | 547mm | 565mm | 583mm | 600mm | 618m |
| Nominal head tube angle | 68° | 68° | 68° | 68° | 68° |
| Tuning Chip induced head/seat tube angle change | ±0.2° | ±0.2° | ±0.2° | ±0.2° | ±0.2° |
| Head tube length | 90mm | 100mm | 120m | 140mm | 160mm |
| Nominal seat tube angle | 75° | 75° | 75° | 75° | 75° |
| Seat tube length | 360mm | 400mm | 450mm | 490mm | 530mm |
| Bottom bracket drop | 68-72mm | 68-72mm | 68-72mm | 68-72mm | 68-72mm |
| Chainstay length | 430-450mm | 430-450mm | 430-450mm | 430-450mm | 430-450mm |
| Wheelbase | 1090-1110mm | 1110-1120mm | 1130-1150mm | 1150-1170mm | 1170-1190mm |
| Trail | 88mm | 88mm | 88mm | 88mm | 88mm |
| Fork offset | 51mm | 51mm | 51mm | 51mm | 51mm |
| Rigid fork axle to crown length | 495mm | 495mm | 495mm | 495mm | 495mm |
| Stack | 595mm | 605mm | 623mm | 642mm | 660mm |
| Reach | 387mm | 403mm | 416mm | 428mm | 441mm |
| Standover | 754mm | 777mm | 810mm | 838mm | 866mm |
Note: Images may not show actual build kit content. Pricing and specifications subject to change without notice. Comparable components may be substituted when necessary to fulfill bike shipments.
