Erik Nilsson joins the bangbang army and hops on hogs with the elderly China Knights motorcycle club to discover how Chongqing has blazed paths to tame its infamously hilly terrain.

Editor's Note: This is Part 5 of the six-part Yangtze-diaries series based on journalist Erik Nilsson's recent 35-day, 2,000-kilometer journey to 11 cities to discover how the Yangtze River Economic Belt has transformed over the 40 years since the reform and opening-up. Scan the code to watch the video.

I was recently recruited into the bangbang army and rode with a motorcycle club of grandpas－and a few grannies－in Chongqing.

It was with a bamboo pole on my back and later, sitting on the back of a retiree's hog, that I came to understand how the notoriously hilly city has improved its infrastructure.

The bangbang porters, who've carried loads slung from shoulder poles uphill for as long as anyone can recall, are vanishing as Chongqing's traffic and economy develop, hand-in-hand.

The mountainous terrain conjured and forged the bangbang. They've been not only necessary to, but also icons of, the city since time immemorial.

I was the youngest among their ranks by many years.

"We're all in our 50s and 60s," bangbang porter Li Chuanshu told me, as I carried a load alongside him.

"No young people want to do this." He's 65.

I found it tricky to balance the boxes dangling from either end of my bamboo pole.

They wobbled－and, consequently, so did I. I swayed to and fro as much as I walked forward at first, as if drunk.

The treacherous topography had long made it tricky to not only go up and down slopes but also to move forward in any cardinal direction－not just on foot as a fulcrum for swaying boxes but even behind the steering wheel of a car.

It used to take 26 hours to drive from downtown to Qianjiang district. It now takes only four hours from the city center to the municipality's farthest edges.

This makes it easier for the China Knights motorcycle club to ride to any corner of the nation－and beyond, to such countries as Russia, Laos and Myanmar.

The group greeted me on the side of a highway by revving their engines. The grumbling drone was like a swarm of giant wasps. They bellowed hellos like feuding lions, roaring in thickly accented Mandarin before I joined them for a joyride.

These elderly bikers live a kinetic existence. They are, on average, older than the bangbang－the youngest is 61, and the eldest 87－but they have thrived as the bangbang have become increasingly obsolete.