The Monkey Lab: Rohloff-Equipped Surly Big Dummy Cargo Bike

28 May 2013

Rohloff-Equipped Surly Big Dummy Cargo Bike

Surly Big Dummy Rohloff cargo bike

We recently completed a Rohloff SPEEDHUB conversion on this Surly Big Dummy cargo bike for a customer in Sacramento, CA. He wanted a bike that offered reliable around town transportation and hauling with the ability to handle off-road touring. He found a used, mostly stock Big Dummy on Craigslist and dropped it off with us to strip the drivetrain and replace it with a Rohloff SPEEDHUB 500/14 system. He was drawn to the SPEEDHUB for its ability to handle the high torque produced when hauling heavy loads in a low gear, not to mention the durability and reliability to circumnavigate the globe. To see another Rohloff equipped Big Dummy being ridden tens of thousands of miles around the world, check out photos from Juan Martinez!

Cycle Monkey Rohloff Speedhub drivetrain

This bike uses an idler wheel to take up chain slack without the use of a conventional derailer-style tensioner

For the rear wheel, we kept the stock Salsa Gordo rim and replaced the Deore hub with the Rohloff Speedhub. We trimmed the DT Swiss spokes in our spoke machine to fit the larger hubshell dimensions of the Rohloff. The front Deore/Salsa Gordo wheel is stock.

The Big Dummy is designed with the SPEEDHUB in mind, as shown by the OEM2 mounting hole (silver bolt to the right of the quick release)

An aluminum Jones H-Bar offers multiple hand positions and a comfortable 45 degree grip angle

Close up of the idler wheel that takes up the chain slack on this bike

This Surly Big Dummy is set up with a chain idler from Terra Cycle to eliminate the need for a derailer style chain tensioner. This solution creates a less vulnerable drivetrain without dangling parts that could get knocked out of alignment by rocks or debris.

This bike is now in daily service hauling, commuting and transporting on the streets of Sacramento, California. With the Big Dummy's 400 pound rider and cargo weight limit, the Rohloff SPEEDHUB was the ideal drivetrain choice for this application. The ability to shift multiple gears while stopped and without pedaling is a huge advantage for riding with loads. Cycle Monkey can convert nearly any existing bike to a Rohloff SPEEDHUB system, please contact us for details. If it's possible, we can do it!

Build details: