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URSA Major Titanium Fatbike Frame

Chumba USA


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We liked the Chumba Ursa Major titanium fatbike so much that we made a special deal with Chumba to buy out all their existing stock for an incredible price and that is why we can offer one of the most well thought out fatbike frame designs for $500 off the original retail price!

The Ursa Major is a modern fatbike design that is as at home on the trails as it is on sand and snow. Whether you set it up Rigid or with Front Suspension, the ability to run any current wheel size and tire combination gives you the ability to dial in the ride for conditions where you live or for those extreme adventures you are planning!

Plus, the URSA Major Frame is made in the right here in the USA!

We'd love to help you outfit your new Chumba Ursa Major frame! Custom build quotes are available on request.


  • Oversized 44mm head tube fits tapered forks and straight steer forks
  • Headset ZS44 Upper / EC44 Lower
  • Designed for use with 100mm Suspension or Rigid 483mm - 490mm forks
  • 31.6mm Seatpost and 34.9 Seatpost clamp
  • English threaded 100mm bottom bracket
  • Paragon Machine Works sliding dropout inserts can be configured geared, singlespeed or Rohloff


  • Made in USA!
  • Ursa Major frames use the strongest oversized 3AL-2.5V titanium tubes
  • The custom 6AL-4V drive side chainstay yoke has a built in ISCG-05 tab for skid plates
  • The shaped downtube has plenty of room for a Bluto fork in 360 degrees of rotation
  • With 3" - 5.0" Tire compatiblity the Ursa Major offers one of the shortest chainstay lengths out there for both tire sizes, 435mm with a 4.0 tire and <455mm with a 5.0" tire.
  • The frame can be used with 190 Quick release hubs or 197 thru axle hubs, depending on the chosen Paragon Machine Works insert. Heck, you can even run a Rohloff Speed Hub if you can get your hands on one!
  • 3 bottle mounts on sizes Large and XL, 2 Bottles on sizes Small and Med
  • Rear rack mounts