Review: Tumbleweed Prospector

Tester: Adam Newman
Sizes available: S, M, L, XL (tested)
Price: $1,450 frame and fork, $2,650 as module with Rohloff hub
Weight: 33.7 lbs

If you’re reading this, it’s likely the thought has drifted through your mind. Maybe on a long ride, or lying awake at night, or chatting with your friends over a beer. The mythical dream. The White Whale. The Perfect Bike.

Daniel Malloy knows this dream. He thought about The Perfect Bike during his years in bike shops. He envisioned The Perfect Bike during his stint at Rivendell. He knew it had to be tough enough for the massive expedition type trips he was undertaking: it had to use legacy standards for easy-to-find replacement parts, and it had to have big tires. Definitely big tires.

Eventually the dream became too real, too lucid. He had to build it. Malloy reached out to custom framebuilder Cameron Falconer to put together a few prototypes, and they were put to the test on a grueling trek across Mongolia in 2015. Malloy took what he learned and applied it to the production models, which were welded in Taiwan and arrived on American shores this past winter.

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The Bike

What is your dream bike like? Is it super light? Exquisitely beautiful? For Malloy, it was a key combination of features that he couldn’t find anywhere else. He wanted to be able to run full-size fat bike tires, but he hated the super wide Q factor they required. On long trips the extra width between the pedals was too uncomfortable. He also loved the durability and simplicity of an internally geared hub, specifically a German-made Rohloff hub. Because the internally geared hub has a fixed chainline, Malloy realized it could be paired with a normal 73 mm mountain bike bottom bracket and still clear the bigger tires. As a result, with a wheel swap the Prospector can fit a 26×4 fat bike tire, a 27plus tire or even a 29plus.

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Like trying to understand the plot to a David Lynch movie, you’re not going to get it unless you look a little closer. The key features of the Prospector that make it stand out in the market are subtle: The chainstay yoke is a custom-cast piece that allows the bike to fit 4 inch tires while still using 73 mm bottom bracket. It can only fit those tires with a singlespeed or internally geared hub, but it can run a single-chainring drivetrain with 3 inch tires or a double crank if you use an offset model like the Surly OD.

The dropouts are similarly special cast pieces, with a derailleur hanger on one side and a purpose-built mount for the Rohloff hub on the other. The Rohloff uses a two- cable shifter and a special junction box that needs to be secured in a certain spot. Many bikes can use it with a simple adapter, but the Prospector is speaking German right out of the box. If you want to use a derailleur or build it as a singlespeed, you can do that too with a traditional 135 mm quick-release hub.

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To tension the chain the Prospector uses an eccentric bottom bracket, in this case a Phil Wood unit that Malloy asked them to make just for the bike. It uses good ol’ threads too, so the selection of bottom brackets and cranksets is nearly infinite. It can also be used for a small amount of geometry adjustment to compensate for the difference between 27plus and 29plus tires.

Above the special bits like the dropouts and bottom bracket, you’ll find a TIG-welded steel frame built from double-butted chromoly tubes. It sports full-length, external housing runs for shifters and brakes, fender and rack mounts front and rear, and triple-hole cargo cage mounts on both sides of the fork and on the upper and lower surfaces of the down tube. Each frame uses size-specific tubing, Malloy said.

About that fork: It looks pretty conventional, but it has a few tricks up its steerer tube. First, the offset is 53 mm, a bit more than a normal 29er fork, and the front hub spacing is actually a rear hub spacing. That is, you need to build a wheel with a rear hub to use in the front, kind of like the original Surly Pugsley. It’s a pretty smart idea that provides some redundancy to the drivetrain. Say your drivetrain blows up in the middle of Madagascar—just swap rear wheel with the singlespeed wheel you used on the front. In fact, this test bike features just this setup.

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The Ride

This bike certainly qualifies as a mountain bike, but compared to a modern mountain bike with very aggressive geometry and lots of bells and whistles, the Prospector seems like a throwback to a simpler time. Yes, it has a 44 mm head tube and can easily run a suspension fork, but if you’re looking to drop into A-Line at Whistler, this isn’t what I’d recommend.

Instead, I think of the Prospector as more of an all-terrain bike. Granted, I rode a size XL, but I liked the upright position, the stability of the long wheelbase and the extra room inside the main triangle for a frame bag. The 18 inch chainstays leave lots of room for big tires and mud clearance, and should keep your heels from rubbing on any rear-mounted panniers.

The handling is decidedly neutral, in a good way. In the way that you get on and you don’t have to think about it too much. Malloy designed it with a slightly taller head tube for more comfort, which I appreciated, and the reach numbers are modest compared to modern trail bikes. I rode the bike equipped 27plus wheels and tires, which I figured would be the most versatile setup of the available options. Shod with WTB’s Ranger tubeless tires, it’s a great setup for all-purpose mixed-terrain use, from singletrack to sidewalks.

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While I recently spent some time on a Pinion Gearbox bike (Tout Terrain Tanami Trail), this is my first extended ride with a Rohloff. It uses a simple twist shifter to move through its 14 speeds. Malloy said he fell in love with the Rohloff because of its high build quality and durability. Some riders have been known to rack up 100,000 miles on them. I didn’t achieve quite that mileage during my test period, but I certainly didn’t have any issues with it either.

While I can’t make an honest assessment of its extreme durability (time might be a flat circle, but mine isn’t infinite), I can say that the shift quality was pretty much par for the course. It will upshift to a harder gear under power, but not as easily as the Pinion. A downshift still requires you to lift pressure off the pedals like a normal bike. A few times it would hang up between gears, or get stuck in the wrong gear. The nicest feature is that it can shift while the bike is stationary—something you don’t think you’d use very often until you have the ability to do it.

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Conclusion

I think it’s easiest for me to sum up the Prospector this way: The frame is essentially a giant accessory for the Rohloff hub. The kind of customer that will gravitate toward it will likely have already made up their mind to use the internally geared hub, so now they’re looking for the perfect platform.

In the end, I think of the Prospector as the bicycle equivalent of a Swiss army knife. None of the tools in its quiver are maybe the best—there are better knives, and better bottle openers—but it’s really the only kid on the block who checks every box in terms of features and specifications. If you’re searching for something that can check all the boxes on your idea of The Perfect Bike, this might be it.

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First Look: Tumbleweed Prospector

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Photos by Tumbleweed Bike Co. 

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Designing bikes for fat tires is a still an evolving science. As fat tires moved from 3.8 to more than 5 inches, the corresponding hub and bottom bracket widths are growing to accommodate all that rubber. Wider bottom brackets mean a wider Q-factor. For those who aren’t familiar with the term, Q-factor is the distance between pedals. Some riders (this author included) find the wider pedal stance of most fat bikes to be uncomfortable on longer rides—not an ideal situation for a long tour. That’s why the Prospector stands out in the fat-bike crowd: It uses a standard 73 mm bottom bracket shell.

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There is more to the Prospector than a standard bottom bracket, but being able to run 26×4 inch tires with a low q-factor is pretty big news. There is also an very nice Phil Wood eccentric bottom bracket for tensioning the chain when using an internally-geared hub or single speed drivetrain. The eccentric can also be used to adjust bottom bracket height when using other tire sizes. The Prospector can fit 29×3 and 27.5×3.25 tires as well.

There are some drivetrain limitations, as there is no free lunch, even with the sweet chainstay yoke that makes this whole bike work. Fat bike tires (26×4) will only work with a singlespeed or internally-geared hubs. Single-ring drivetrains will function fine with most plus tires, but multi-ring cranks will need to be Boost offset to work.

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Both front and rear wheels are 135 mm with standard quick releases, making for an easy swap if something goes wrong with a cassette body or IGH.

Here are the bullet points from Tumbleweed on the bike specs:

  • Tumbleweed hollow cast BB yoke (Designed by Anna Schwinn) for maximum tire and mud clearance. Compatible with most Shimano mountain cranksets
  • 73 mm Tumbleweed exclusive Phil Wood Eccentric Bottom Bracket.
  • Double butted, heat treated chromoly tubing.
  • Tumbleweed vertical dropouts (Designed by Anna Schwinn) with Rohloff OEM slot and chainstay mounted disc brake. M6 and M5 Rack and Fender mounts.
  • Replaceable derailleur hanger (Wheels Manufacturing number 6)
  • Braze ons: Front and rear rack and fender mounts, three water bottle mounts on frame, triple water bottle mounts on fork
  • 135mm symmetrical QR rear hub spacing
  • 135mm fork spacing for rear disc spaced hubs, allows front and rear wheel interchangeability. Unicrown, 100mm suspension corrected
  • Tire clearance for 26×4 on 65mm rim (Rohloff SPEEDHUB or singlespeed only), 29×3 on 50mm rim, or 27.5×3.25 on 50mm rim
  • Chainring clearance: 24-38 Mountain Double, or 24-32-42 Mountain Triple. Chainring clearance is only limited when the Eccentric BB is in the far rearward position. Larger chainring combinations may be used if this rear position is avoided. In order to use a 3 inch tire with derailleurs, a 1x or offset 2x crankset must be used.
  • 31.6mm seatpost, 35mm seat clamp
  • Available Colors: New Mexico Turquoise and Desert Sandglow

MSRP is $1,450, but there are discounts for early orders. Bikes should ship in February. There is a “module” option as well, which will include a Rohloff Speedhub, shifter, cables/housing and disc rotor for $2,650.00

Check out the video for a full explanation of with the development of this bike.

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