The world of long-distance fundraising journeys is littered with singularly focused runners, cyclists and motorbike riders.Only a special few will clock up the kilometres conjoined, on a bicycle built for two.Husband and wife duo Huw and Carolyn Thomas have had only the occasional disagreement from their seats aboard Orion, a tandem bike they are pedalling 16,000km to help disaster relief charity ShelterBox.Former journalists from Cornwall in the United Kingdom, they frequently strike up friendships and conversation with onlookers drawn in by their curious ride.Besides, said Mr Thomas, it was good for their marriage."If we were on single bikes it would be hard to be riding together [at the same pace]," he said, pulling into Corrimal late yesterday."With tandems we're never very far apart. We can sit and chat if there's not too much traffic."Photographs on the pair's blog tandem10.wordpress.com reveal Mr Thomas is a third-generation tandem enthusiast.His parents David and Joan Thomas and grandparents Will and May Wiggs are pictured looking sweet upon their seats in a section of the blog explaining "why Carolyn had no choice about riding a tandem". But this journey began in Vancouver on August 8 and has covered more than 5400km in Canada and more than 2100km in New Zealand. The pair were recently hit by a slow-moving truck as they rode in a marked cycle lane outside Noosa. Orion copped a badly warped rear wheel but the riders were unhurt and soon back on the road.The Australian leg will cover almost 1800km through Queensland and NSW, concluding this month in Kiama.The final 4600km European leg is expected to finish on July 31 at ShelterBox's international headquarters in Cornwall, England.ShelterBox has provided aid after more than 140 disasters in more than 70 countries since 2000.It is best known for its disaster relief tents - capable of housing a family of 10. These form the heart of highly practical boxes of supplies, often including tools, thermal blankets and a multi-fuel stove.