By Guy Delauney
BBC News, Cambodia
Cycling is commonplace in Cambodia, and riding a bike is also a great way for a foreigner to meet local people, find something in common, and even build a lasting friendship.
As social lubricants go, the bicycle is seriously under-rated.
For adults in many, if not most countries, cycling is a minority pursuit.
But for us grown-ups who persist in doing what certain, misguided people like to label "kids' stuff", there is often an instant bond - one that can transcend all sorts of differences in background, nationality and circumstance.
That is certainly the case in Cambodia.
For proof I only need to look at the photo of a former Khmer Rouge sniper, turned wildlife ranger, taking a spin on my mountain bike.
We had met on a ride in the Mondulkiri jungle.
But of all the characters I have encountered in the saddle, there has been no-one quite like Tim Durrin.
Tim Durrin's bike has helped him make friends including Cambodian Laim
We met in a cafe rather than on the road or trail.
He started laughing at a story I was reading to my children - I noticed his bike helmet and water bottle - and we got talking from there. Tim's unkempt mop of curly hair suggested an ebullient personality.
And so it proved, as he raved about riding through the Cambodian countryside and meeting the local people.
He was taking a few months to get to know the country, he said.
I gave him the details of a couple of bike shops in case he needed any parts - and suggested that he take his bike to Siem Reap - and ride around the Angkor temples.
By the time I left the cafe, we were Facebook friends.
This meant I could follow Tim's adventures online.
And his updates were among the finest examples of anyone using a bike as a social lubricant
It was simple. Tim would stop whenever he saw something - or someone - interesting.
On one occasion a group of people raking puddles by the sea in Kampot province piqued his curiosity.
He went over to find out what was happening.
Many Cambodians are highly tickled by the idea that someone who could afford a car should be indulging in such a sweaty, dirty activity
At first he was met with surly indifference.
But then he pointed to the bicycle tattooed on the inside of his upper arm.
Everyone smiled and laughed.
"Barang chi gong" they said - foreigner riding a bike.
It is a phrase I know well - many Cambodians are highly tickled by the idea that someone who could afford a car should be indulging in such a sweaty, dirty activity.
The ice having been broken, Tim spent the rest of the day collecting sea salt with the locals.
But the trip up to the temples did not go so well.
Riding back to town at dusk, Tim did not see the pothole in front of him until it was too late.
He flew over the handlebars and into the back of a parked pickup truck. The bike was a write-off, and the rider's knees were not much better.
Reading the messages from dozens of concerned friends prompted me to search for Tim's name on Google.
The results were, to say the least, eyebrow-raising.
It turned out that he had been in the US army - and seen active service in Iraq.
Burned out by this experience, Tim had got involved with a group of veterans opposed to American involvement in the region.
And rather more unusually, he was making efforts to reconnect with his family's Native American heritage by attending pow-wows and sweat lodge ceremonies (gatherings of North American Native people)
I would never have guessed that the open and friendly figure I had met was a combat veteran.
Or, as Tim revealed when he returned to Phnom Penh, recovering from drink and drug issues.
His trip to Cambodia was a step towards finding redemption - and rediscovering parts of his character that had been lost in teenage recklessness and an impetuous decision to join the army.
The bicycle was part of it too - a form of transport that made Tim feel childishly free, and open to the people and situations he came across.
But it was not just about himself.
Tim had decided he wanted to do something to help others.
As Cambodia is one of the world's poorest countries, and US military intervention has caused great suffering here, it seemed like the ideal place.
Tim took me to the side entrance of a Buddhist pagoda to meet a friend.
Laim was from a small village in Siem Reap province - and studying medicine in the capital.
Tim is helping Laim work toward his dream of free rural healthcare
Like many poor students, he was living with the orange-robed monks to save cash.
But he spoke passionately about his desire to bring free health care to rural Cambodia in the future.
Laim's plans had impressed Tim so much that he had decided to sponsor the young man's studies.
He had bought him a laptop - and also provided an endowment to the village school which Laim had helped to set up.
And what could be the connection between a part-Native American, Iraq conflict veteran - and a rural Cambodian with dreams of making a difference?
The answer was securely locked to the railings outside the monks' quarters: Laim's well cared-for mountain bike.
Both men, and of course your own correspondent, are dedicated cyclists.
How to listen to: From Our Own Correspondent
BBC Radio 4:
A 30-minute programme on Saturdays, 1130.
Second 30-minute programme on Thursdays, 1100 (some weeks only).
Download the podcast
BBC World Service:
Hear daily 10-minute editions Monday to Friday, repeated through the day, also available to listen online.
Read more or
explore the archive