Schlumpf-Equipped Airnimal Chameleon Folding Bike

After struggling with a troublesome front derailleur on his Airnimal Chameleon folding bike, Bruce Metras of B. Metras Company (San Rafael, CA) upgraded his bike with the installation of a Schlumpf Speed Drive.

The Schlumpf system simplifies the drive train by using a single chain ring in the front that is connected to a two-speed internal gear system encased in the bottom bracket. Since the chain remains on a single ring, there is no possibility of an overshift occurring that would result in a dropped chain. This set-up also allows riders to access all available gears on the rear cassette, as the centered chain line eliminates cross-chaining.

The 1.65 ratio change of the Schlumpf SpeedDrive offers a direct gearing replacement for the original front derailleur and double crank set. For smaller-wheeled bikes, like the Airnimal, this option is especially useful, as it gives riders the same effective gear ratios available on standard bikes without requiring the use of extra-large chain rings. Often, the chain ring size needed to get the desired output is so large that it is not readily available and leads to shifting problems due to component size mismatch:

• Front derailleurs are shaped to work with the chainrings sizes commonly found on bikes with 26" and 700c wheels. Larger rings do not match this shape well.
• The difference in tooth count between two chain rings increases as their size grows (assuming a fixed ratio between them) and quickly exceeds the capacity of the front derailleur.
• The chain angles created by the large chain ring and shorter chain stays of a smaller-wheeled bike cause poor shifting and excess chain and sprocket wear.

With a Speed Drive, these issues are eliminated. Riders can use a single smaller ring and still get the larger gearing that is desired without any of the problems associated with using larger chain rings on small-wheeled bikes. Riders of standard bikes also benefit from the Schlumpf set-up. Check out our previous post on using a Schlumpf Speed Drive on a fixie.

Bike highlights

• Frame: Airnimal Chameleon folding bike
• Front Gearing/Front Derailleur Replacement: Schlumpf SpeedDrive Gearing System
• Crank arms: Truvativ left-side square taper arms with right-side pedal insert on one arm

Rohloff-Equipped Surly Ogre 29'er Mountain/Touring Bike

This Surly Ogre is a great example of an economical Rohloff build done for a customer in Ohio. He was looking for a no-fuss bike that he could ride off-road on his local trails and also take on long-distance tours. The Rohloff SPEEDHUB 500/14 was a natural choice for the drive train. Having ridden a Big Dummy for several years, he was familiar with the quality and value of the Surly brand and looked to their new Ogre frame for his new bike. Parts were chosen to give a good balance of performance, durability, and value.

Rohloff-Equipped Giant Trance X Demo Mountain Bike from Cycle Therapy

Finding a shop that has a Rohloff SPEEDHUB 500/14 to test ride can be difficult. Fortunately, for riders in the Rome, GA area, Cycle Therapy has this Giant Trance X setup for demo.

The bike highlights some of their favorite parts. With 125mm of rear wheel travel and 160mm up front, this bike can handle handle a wide variety of terrain.

If your shop currently has a Rohloff demo bike or is interested in setting up a couple demo bikes, let us know.


Build details

• Frame: Giant Trance X
• Fork: Fox Shox TALAS 36
• Rear Shock: Fox Shox FLOAT RP2
• Handlebar: Easton Haven Carbon
• Seatpost: Kind Shock Dropzone Adjustable Height
• Shifter: Rohloff
• Front Hub: Chris King ISO 20mm
• Rear hub: Rohloff SPEEDHUB 500/14
• Rims: Mavic XM819 Disc Tubeless
• Tires: Michelin Wild Rock'r
• Cranks: Shimano Saint
• Brakes: Shimano XT

Schlumpf-Equipped Brooklyn Machine Works Gansta Fixie

When Schlumpf redesigned their clutch plates to make them compatible with fixed gear bikes, Neil wanted a unique frame to test/showcase a Speed Drive unit. The Brooklyn Machine Works Gansta Track frame fit the bill with its pierced top tube, box-section fork crown, and airfoil fork legs, seat stays, and chain stays. Only problem - the frame had no provision for a brake. After a couple calls to BMW and some brainstorming on their part, they agreed to fabricate a disc brake mount for the fork. Now we were in business.


The frame got a sparkly clear coat over a gloss black base, so we wanted to use shiny silver wheel parts to compliment this finish. We went with polished Phil Wood hubs - 32 hole bolt on disc front and 36 hole fixed/fixed bolt on high flange track rear- laced into bright silver Velocity Deep V's using Sapim Race spokes and brass nipples. A 2 leading/2trailing lacing pattern was used on the front and a 3 leading/3 trailing lacing pattern was used on the rear. Spoke color (black/silver) was alternated between each bundle of spokes (bundles of 4 on front wheel, bundles of 6 on the rear) to give the wheels contrast while spinning.

The heart of the project was the hidden gear box. The Schlumpf systems give you two gear ratios using a single chain ring that is connected to a two-speed internal gear system encased in the bottom bracket. The Speed Drive model offers a ratio change just slightly larger than a standard road front derailleur and double crankset (65% change). Since the chain remains on a single ring, a single speed or fixed gear bike with a tensioned chain can become a 2-speed. The updated clutch plate design allows the gear box to transmit torque in two directions, making it compatible with fixed gear bikes.

The gear ratio is changed by intentionally knocking buttons on each side of the bottom bracket axle with your heels (silver button in the center of the crank set). In one mode, the Speed Drive acts like a standard bottom bracket and crank set: the chainring and crank arms spin at the same rate. In the other mode, the Speed Drive gearbox over-drives the chainring: the chainring now spins faster than the crank arms, providing a larger effective chainring size.

Build details

• Frame: Brooklyn Machine Works Gansta Track
• Fork: Brooklyn Machine Works Gansta Track with Custom Disc Brake Mount
• Headset: Ritchey Internal
• Stem: Thomson Elite
• Handlebar: Custom Groovy Cycle Works Luv Handle
• Seatpost: Thomson Elite
• Front Hub: Phil Wood Disc
• Rear hub: Phil Wood High Flange Track, Double Fixed
• Rims: Velocity Deep-V
• Spokes: Sapim Race
• Nipples: Sapim Brass
• Lacing Pattern: 2 leading/2trailing front; 3 leading/3 trailing rear
• Crank Arms: White Industries VBC
• Gearbox: Schlumpf Speed Drive
• Brake: Avid BB7
• Brake Lever: Paul Components E-Lever
• Disc Rotor: Dirty Dog Dragon
• Pedals: Shimano DX

Center Track Belt Parts in Stock!

Today, the Fedex man came with a box of long-awaited Center Track belt parts from Gates Carbon Drive, including pulleys for the Rohloff SPEEDHUB 500/14.

Center Track represents the next generation of the belt drive system from Gates Carbon Drive. This version brings improvements in both installation and performance. Here's an overview of the design changes.

The flange on the pulleys has been moved from the outside edge to the center, and a mating groove has been cut down the middle of the belts. This allows the belt to be fully captured by each pulley, improving both installation and operation. The system is easier to setup as there is now more tolerance for misalignment between the front and rear pulleys. Most importantly, it also reduces the chances of the belt wandering off the pulleys while riding.

The mounting surface for the pulleys has also been moved to allow for adjusting the alignment between the front and rear pulleys. By moving the mounting surface away from the edge to an off-center position, each pulley can be installed in one of two orientations, which moves the teeth either inboard or outboard. This feature helps bring the pulleys into the same plane, improving the belt line.

Center Track pulleys are currently available in the following sizes:

• Front, 4-Bolt, 104mm BCD: 46T, 50T, 55T
• Front, 5-Bolt, 130mm BCD: 46T, 50T, 55T, 60T
• Rear, Rohloff Version: 20T

Note: 22T Rohloff rear pulleys expected in approximately two months

Center Track belts are currently available in the following sizes: 113T, 115T, 118T, 122T, and 125T.

Rohloff-Equipped, Belt Driven Firefly Custom Titanium 29er Mountain Bike

Signature Cycles (NYC) bike shop coordinated with Firefly Bicycles (Boston, MA) to design this 29er mountain bike. The customer was looking for a high-performance, low-maintenance bike to spend more time riding and less time fixing his bike.


The integrated Rohloff SPEEDHUB and Gates Carbon Drive belt system provides a virtually maintenance-free drive train. This combination requires only an annual oil change for the hub, but no other regular maintenance or lubrication. With the belt drive system projected to last over 10,000 miles, this drive train will provide many years of reliable service.

To accommodate the belt drive system, Firefly used a Paragon Machine Works titanium tube splitter on the right seat stay. This provides a clean and simple solution to insert the belt into the frame.

Finishing details include Rohloff-specific cable routing for a clean look and Paragon Machine Works Rocker adjustable dropouts to tension the belt.


Build details

• Frame: Firefly custom titanium
• Fork: Fox Shox F29
• Headset: Chris King Inset
• Stem: Thomson X4
• Seatpost: Firefly titanium
• Shifter: Rohloff
• Front Hub: Chris King ISO 15mm
• Rear hub: Rohloff SPEEDHUB 500/14
• Rims: No Tubes Arch
• Tires: No Tubes Crow
• Cranks: Shimano XT
• Chainring: Gates Carbon Drive Center Track
• Chain: Gates Carbon Drive Center Track
• Brakes: Shimano XT
• Pedals: Shimano DX
• H2O Cages: King Cage titanium

Happy New Year from Cycle Monkey!

Greetings from our nation's capital! For the past few months, Cycle Monkey has been serving you from the East Coast -- Washington, DC to be exact.

Relocating from Berkeley has triggered some interesting new experiments in the Monkey Lab, while allowing for us to carry on some key Cycle Monkey traditions.

From the start, Cycle Monkey has been a cycle-powered business, with several bikes ferrying goods to local customers and the post office to ship packages to those more distant. For large shipping days, we pull out our cargo bike from Bilenky Cycle Works (Philadelphia, PA). With this bike, we can stack the packages high on the front platform and fill up paniers on the rear rack. Not only does this elicit smiles along the route, but also challenges folks to rethink how bicycles can be used.

Adding to its uses, we have found the cargo bike to be the perfect ride home from the local metro station. There's nothing quite like it in the Kiss and Ride area! Katie has found new joy in railing corners while sitting on the platform, but sometimes wishes she had control of the brakes. Regardless, this experiment has made our family transition to living without a car that much more fun.

Biking is a cornerstone of our business and family. We would like to share this love of cycling with you through this blog. From the Monkey Lab, we will feature our favorite bike builds, components, builders, riders, and rides. Happy pedaling!