Tumbleweed Prospector Frameset


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The Prospector is a timeless and rugged expedition mountain touring bike, designed around the stalwart Rohloff Speedhub drivetrain. It’s a bike designed to be reliable, tough and field serviceable in the harshest of conditions. In the face of ever changing bicycle part standards and the integration of exotic materials, the Prospector is built to last and to buck the trend of short product cycles and throw away upgrade culture. We believe that the most important features of a reliable expedition bike are a comfortable fit, a tough frame/fork, strong wheels, reliable components, and as much tire/mud clearance as possible.


The Prospector has several features that separate it from other expedition bikes. The best chromoly tubeset available is used, it’s oversized, heat treated, multi-butted with integrated gussets, and it’s custom drawn just for the Prospector. A Phil Wood eccentric bottom bracket offers half an inch of bottom bracket height adjustability, custom cast dropouts work seamlessly with the Rohloff hub, and a hollow chainstay yoke maximizes every millimeter of mud and tire clearance to round out a complete package that can take you anywhere in the world with confidence.

While the Prospector is derailleur compatible, it was designed specifically around the Rohloff SPEEDHUB, a 14 speed internally geared drivetrain that has proven itself to be supremely dependable and capable.

What’s new with the current batch of Prospector frames?

We added 10mm to the effective top tube length on all sizes, to work even better with the swept back Persuader bar that didn’t exist when we first designed the Prospector. We also added a 150x15mm thru axle fork option.

Prospector Fork Options

We have three steel fork options for the Prospector: If you don’t plan to run suspension, go with options 1 or 3.

1. 135mm Quick Release fork with rear disc spacing: The original fork that we offered with the Prospector, uses the same spacing as the frame, allowing you to run two rear wheels on the bike, useful if you run the bike singlespeed and want to run two different gear ratios. Wide hub flanges produce an incredibly strong wheel with great spoke triangulation.

2. 110x15mm Boost thru axle: Allows you to swap between rigid and suspension forks without needing to build a new front wheel. Lots of hub options, but narrower hub flanges don’t work well with fatbike rims that have offset spoke holes, they produce a wheel with little to no spoke triangulation, but work great with non offset rims.

3. 150x15mm thru axle. The modern fatbike front hub standard. Lots of hub options, wide hub flanges for great spoke triangulation and super strong wheels. You can swap this fork with something like a RockShox Bluto in 80-120mm of travel.


  • Frame Material: Chainstay width is 140mm, crank arms must have 144mm inner width, 24mm spindle recommended
  • Rack/Fender: Compatibility Rack and fender compatible, three bottle mounts on frame triangle
  • Fork: Unicrown Chromoly steel with 135mm quick release, 110x15mm thru axle (thru axle included) or 150x15mm thru axle (thru axle included), upper and lower rack mounts, fender mounts, triple bottle cage mounts on fork legs, internal dynamo wire routing


  • Max Tire Clearance: 26×4.0″, 27.5×2.8-3.8˝ and 29 x 2.1-3.0˝, individual tire and rim combos affect tire clearance
  • Headtube: 44mm I.D.
  • Headset Recommend: EC44 lower cup. ZS44 upper cup.
  • Bottom Bracket: 73mm, threaded English (1.37˝ x 24t) Phil Wood Eccentric Insert. M8 cupped point set screws (8mm x 1.25 thread pitch)
  • Rear Axle: 135mm quick release
  • Seatpost: Diameter 31.6mm
  • Dropper Seatpost: Compatibility Internally routed for dropper post
  • Seat Clamp (included): 35mm
  • Drivetrain Compatibility: Rohloff or 1x derailleur drivetrain recommended
  • Brake Compatibility: 51mm I.S. disc caliper mounts, 180mm max rotor size, minimum 160mm rotor
  • Fork Axle to Crown: 483mm
  • Fork Steer Tube Length: 300mm
  • Rear dropouts: Vertical with integrated non-driveside Rohloff OEM slot and replaceable derailleur hanger, 135mm quick release or bolt-on hub spacing compatibility; features threaded M5 and M6 eyelets for fenders and racks
  • Chainring clearance: 1X Boost, 1X Super Boost
  • Crank clearance: Chainstay width is 140mm, crank arms must have 144mm inner width, 24mm spindle recommended