Surly Pugsley Fat Bike with Suspension Fork, Rohloff SPEEDHUB 500/14, and Gates Belt Drive

Fatbikes are known for their wide tires’ ability to provide grip and traction in just about all trail conditions. We've built many of these bikes with Rohloff SPEEDHUB 500/14 gear hubs and several with a Gates Carbon Drive belt system as well, but how would a fatbike be improved if you added a suspension fork to the equation? That was the question we intended to answer with this Surly Pugsley build. Apparently the same question had been on many other peoples’ minds because the bike attracted plenty of attention when we showcased it in our booth at the Interbike tradeshow last September.

The goal for this Pugsley was twofold. First, we wanted to experiment with a more aggressive handling trail-specific fatbike. We also wanted to create a bike that would pique the interest of bike shop owners and industry insiders at Interbike, which is the bike industry’s largest trade show. Like the Surly Krampus build that also drew people into our booth, this Puglsey is one of the few Monkey Lab creations not built for a specific customer but rather as an experimental show bike.

Fatbikes offer a few inches of pneumatic suspension within the tires and do a great job of smoothing out small to medium sized bumps. However, there is a very clear lack of suspension when you get into drops and bigger bumps, and the tires tend to bounce pretty severely when you hit rockier terrain. Because the tires have no rebound control, they spring back very quickly, which can interfere with the bike’s handling. A suspension fork solves the rebound problem, allowing the wheel to spring back slowly and smoothly instead of sending you bouncing off the trail. It also offers the additional cushion desired for tackling rougher terrain. Paired with the traction of a nearly four inch wide tire, we suspected a suspension-equipped fatbike would make for a very stable and confidence-inspiring ride.

Carver Bikes’ 110mm travel inverted Trans-Fat fork is one of the few fatbike-specific suspension forks available. The Pugsley frame is designed for an 80mm suspension corrected rigid fork, so installing the taller 110mm travel fork raises the front end, which slackens the headtube angle and increases bottom bracket clearance. While the slack headtube angle helps in dealing with technical trails, the taller head tube raised the handlebars higher than we wanted them, so we installed the Thomson stem and Salsa Bend 2 bars in their downward-rise positions to keep the handlebars about level with the saddle.

For the rear wheel build we laced a black Rohloff SPEEDHUB to a Surly Marge Lite rim. For the front wheel we used the hub that is included with the fork - a special fatbike-specific hub with 135mm spacing and a 15mm through axle - and also laced it to Surly’s Marge Lite rim. We chose the 65mm Marge Lite rims over Surly’s 82mm Rolling Darryl rims because the slightly narrower rims are more maneuverable for singletrack riding. We fitted them both with Surly's 26x3.8 Knard tires.

The Rohloff SPEEDHUB is ideal for both mountain bikes and fatbikes, which are meant to be “all terrain” vehicles that have to deal with varying trail conditions. Because the SPEEDHUB’s shifting components are housed inside the hubshell, there are no derailleur parts hanging off the bike to get clogged with mud or hit by rocks. If you’ll be riding technical terrain or in challenging conditions there is no better choice than a SPEEDHUB.

The Gates Carbon Drive belt system provides a durability advantage similar in concept to the SPEEDHUB. Because the belt is one continuous loop reinforced with carbon fiber, it is very hard to break or separate. It does not stretch and requires no oil. When paired together, the SPEEDHUB and Gates Carbon Drive create one of the most durable drivetrains available, and one that is nearly maintenance-free. Since the Pugsley frames are not made to be belt compatible in their stock form, we sent this frame to a local framebuilder to have a tube splitter welded into the seatstay so we could install a belt into the rear triangle.

When we took the bike out for a few quick test rides it felt incredibly stable and well-grounded, as we had predicted. The large tires gave us the confidence to take corners fast, but the suspension fork made us feel like we could plow over the larger obstacles that the bike wouldn’t normally be able to handle at speed.

If you’re in the market for a suspension or Rohloff equipped fatbike contact us to see what we can put together for you.

Build Details:

• Frame: Surly Pugsley
• Fork: Carver Trans-Fat
• Headset: Cane Creek
• Stem: Thomson Elite X4
• Handlebar: Salsa Bend 2
• Shifter: Rohloff
• Grips: ODI Rogue Lock-On
• Seatpost: Thomson Elite
• Saddle: Selle Anatomica Titanico
• Seat Clamp: Salsa Flip Lock
• Front Hub: Fatbike hub 15mm thru axle
• Rear hub: Rohloff SPEEDHUB
• Spokes: Sapim Race
• Nipples: Sapim Brass
• Rims: Surly Marge Lite
• Tires: Surly Knard 26x3.8
• Cranks: Race Face Turbine
• Pedals: Acros A-Flat
• Bottom Bracket: Race Face
• Chain ring: Gates Carbon Drive
• Rear Sprocket: Gates Carbon Drive
• Chain: Gates Carbon Drive belt
• Brakes & Levers: Magura MT2
• Rotors: Magura Storm