'It's an engineering feat' - Why this 23kg bicycle has two chains

Jackton Achola runs a bread delivery service in Kenya. He gathers the loaves, places them into colourful pallets, and stacks them high, above his head, on the pannier of his Buffalo bike. He then secures the load down with two rubber cables, and pedals out across his community in Kisumu.

On one trip, Achola can distribute enough food for around 480 people. “I’ve done it for so many years,” he says. Recently, something has changed.

Achola is one of eight testers in his country who have been trialling World Bicycle Relief’s (WBR) latest Buffalo model, equipped with its new AK2 system – a drivetrain with two chains. It’s a revolutionary concept, one that took two years to develop, and has been patented with the help of US parts manufacturer SRAM.

The idea, WBR’s Michael Kelly explains, came after comments from testers like Achola, who had been using the previous singlespeed Buffalo bike. “One of the pieces of feedback was the desire to add a gear to the bike when you’re riding under a heavy load,” Kelly explains. “That was sort of the dream behind it.”

The double-chain drivetrain is found on the Utility S2 Buffalo bike, the latest model of WBR’s flagship product. Since its launch in July, it has undergone thousands of miles of testing, and won design awards at bike shows. Now, it’s being rolled out into communities.

“The philosophy of the Buffalo is that you have components that are going to survive the challenges,” Kelly explains. Where WBR operates in Sub-Saharan Africa and South America, such obstacles include rough terrain, extreme heat, and the need to bear heavy cargo, often exceeding 100kg.

“You can’t have external derailleurs that are going to get gunked up or damaged, and then not have the ability to service those when you’re in these remote environments,” Kelly continues. “The traditional derailleur systems and other mechanisms just aren’t lasting, right?”

The idea for the two-chain system came from an engineer at SRAM, a company established by the founders of WBR. “These are the guys innovating for riders on the Tour de France,” says Kelly. They’re also innovating for riders like Achola.

So how does the two-chain system work? “Essentially,” Kelly starts, “you have these two different chain rings that are at different tensions. What we were able to do was engineer a mechanism that allows you to, through a backpedal shifting motion, cause the freewheel to shift from one chain tension to the other.

“We were able to add this extra gear without adding any complicated external derailleur or wiring.”

The bike is made at the Giant factory in Taiwan, and shipped to WBR’s seven programme countries: Zimbabwe, Uganda, Kenya, Zambia, Malawi, Tanzania and Colombia. The cost of one bike, from the extraction of its materials to delivery with its owner, is around £145 ($180). Though they can be purchased, those on the programme receive them for free.

“It’s about building a bicycle ecosystem in the communities where we operate,” says Kelly. “We have something like 3,500 mechanics that we’ve trained in our program countries, as well as over 100 Buffalo bike retail shops.”

The new two-chain system, Kelly says, is “simple enough” that any trained mechanic can repair it. “It was really sort of an engineering feat to figure out,” he adds. “The feedback so far from our test riders and the people that are getting access to this bike is that they love the extra gear.”

It’s no surprise, too, that a second gear has been so welcome. The bike itself, built for durability rather than performance, weighs 23kg – more than three times the UCI minimum weight limit. The frame is made from steel, the rims from aluminium, and there’s a kickstand for easy loading and unloading.

In the communities WBR serves, the new model has been a “game changer”, Kelly emphasies. “It’s a tried and tested, robust workhorse that’s been designed to work in these environments.” Having surpassed 850,000 bikes distributed, the non-profit organisation is now excitedly homing in on the 1,000,000 milestone.

What this means is that more parents, school students and business owners like Achola can travel through their communities faster. Thanks to the two-chain system, their journeys have now gotten easier. “I really would like this bicycle to improve the whole world,” Achola says. And it is, one swift backpedal at a time.