Surly Krampus 29+ Mountain Bike with Suspension Fork, Rohloff SPEEDHUB500/14, and Gates Belt Drive

Sometimes the team here at Cycle Monkey dreams up a project that is not specifically for a customer but rather to satisfy our own curiosity. We chalk it up to product research, but these projects also have a bit of a selfish motivation: we like to build cool bikes! We put together this Surly Krampus to showcase in the Rohloff booth at the Interbike trade show in Las Vegas last September. The various customizations on this build were very popular at the show and prompted plenty of people to stop by and marvel at the Rohloff hub, belt drive, and suspension fork we had installed on the frame. 

The goal for this build was to create a bike that could be ridden more aggressively through rock gardens, off drops and jumps, and down steep descents. Surly’s Krampus comes stock as a fully rigid 29er with large volume tires that can care of some of the harsh bumps found on trails. Its three inch wide tires on 50mm wide rims provide a fair amount of pneumatic suspension, but in certain situations, the bike is very clearly rigid.

Since the frame’s geometry lends itself well to fast, aggressive riding, we figured that adding a suspension fork would transform the bike into a very capable all-mountain style hardtail. Surly designed the bike to be compatible with 100-120mm suspension forks, but there are currently no forks officially available that clear the large tires.

After doing some fork research, we fitted a Fox F29 fork, which just barely provides enough clearance for Surly’s 29x3 low-tread “Knard” tires to pass through the fork’s arch. With 120mm of travel, the handling of the bike feels neutral and predictable, and there is enough travel to handle a range of trail conditions.

For the wheels we laced up Surly’s 32 hole Rabbit Hole rims to a Hadley front hub with a 15mm thru-axle and the Rohloff SPEEDHUB 500/14 rear hub. Both wheels use Sapim Race spokes and brass nipples for a solid wheelset.

The SPEEDHUB is well suited for aggressive mountain biking. The most common mechanical problems that riders encounter when riding rough, rock-strewn trails often have to do with the derailleur. Rear derailleurs hang off the side of the bike where they can easily be hit by stray rocks, scraped on roots or trees, or clogged with mud or dirt. The SPEEDHUB’s internal shifting mechanism, however, puts all of the shifting elements inside the hubshell, where they are not exposed to the elements or susceptible to impact damage.

We used a Gates Carbon Drive belt system with the SPEEDHUB to ensure the drive and shift system would be even more durable. The belts have at least twice the lifespan of the longest lasting chain, do not stretch, and do not require oil. However, because the belts are manufactured as one continuous loop that cannot be disconnected, the frame needs to have a split point in order to install the belt. Since Surly frames do not come stock with this feature, we sent this frame off to a local frame builder to get a tube splitter installed in the seatstay.

To complete the aggressive-handing qualities we used a short Race Face Atlas stem to keep the steering maneuverable and Salsa’s wide Whammy Riser bar to provide ample leverage. Lastly, we installed Magura’s MT4 hydraulic disc brakes and larger rotors to supply plenty of stopping power.

The bike was a big hit at Interbike and visitors to our booth were excited about how we had re-imagined and transformed the Krampus into a capable all-mountain hardtail. Contact us if you’re looking for this style of bike for yourself.

Build Details:

• Frame: Surly Krampus
• Fork: Fox Float 29
• Headset: Chris King Inset
• Stem: Race Face Atlas
• Handlebar: Salsa Whammy Riser
• Shifter: Rohloff
• Grips: ODI Rogue Lock-on
• Seatpost: Thomson Laid-back
• Saddle: Selle Anatomica Titanico X
• Seat Clamp: Surly
• Front Hub: Hadley 15mm Thru-axle
• Rear hub: Rohloff SPEEDHUB 500/14
• Spokes: Sapim Race
• Nipples: Sapim Brass
• Rims: Surly Rabbit Hole
• Tires: Surly Knard
• Cranks: Race Face Turbine
• Pedals: Shimano XTR PD-M985
• Bottom Bracket: Race Face
• Chain ring: Gates Carbon Drive
• Rear Sprocket: Gates Carbon Drive
• Chain: Gates Carbon Drive
• Brakes & Levers: Magura MT4
• Rotors: Magura Storm