The duo left Los Angeles on 11 May and rode into Boston on 28 June. They reached the finish line after nearly seven weeks of intense riding. Chris and Catherine have now exceeded their fundraising target of £3,415 – representing £1 for WaterAid for every mile they have cycled. The achievement is especially incredible for Chris, an orthopaedic surgeon at Edinburgh’s Royal Infirmary, who just a few years ago weighed over 27 stone and struggled to complete the most basic exercise. The route took them along the Rockies, through the Mojave desert, across the Midwest and the Great Lakes. Finally, they crossed over the Appalachian Mountains before reaching Boston on Friday 28 June. Chris said: "Crossing through the Mojave desert was the most challenging part. The temperatures reached 119 degrees plus (48º C) it was like riding in an oven. It made us realise just how important water is in the desert. "The most fun part was the hills in Missouri; we did 148 roller coaster hills in one day with 5,000 feet of climbing over 80 miles. "Getting enough food was also a challenge for me. Even though I had my gastric band adjusted before I left I still didn’t want to eat. I’m using over 6,000 calories a day and I need to make this up somehow, but it’s still a real challenge for me to consume enough food." Chris also struggled with altitude sickness when crossing the Rockies – but managed to recover quickly and continue the challenge. Catherine, 22, an environmental geography student at the University of York, said: "Staying hydrated has been a challenge, especially through the desert where we were literally having water poured over us every 20 miles or so. "The water on our backs was for drinking and the water bottles on our bikes were for pouring over our arms, legs and head to keep cool whilst cycling." Water has been vital to Chris and Catherine on this trip, and not only when crossing the valley. Chris says: "Every 15 minutes cycling we’re supposed to drink to keep up hydration. Why shouldn’t everyone in the world have the luxury of drinking every 15 minutes if they want to? We are very glad to have raised money for WaterAid." Sarah Walker, WaterAid Community and Events Manager, said: "Congratulations to Chris and Catherine for completing such an impressive challenge for WaterAid. It can cost as little as £15 to ensure one person has a lifetime access to clean water and improved sanitation, so their efforts could potentially transform the lives of more than 225 people." Chris made the decision to lose weight during a business trip to China in 2006. Chris said: "I was at the Great Wall of China and was so unfit that I couldn’t manage to get up ten steps. I decided then that I wanted to do something." The following year, Chris had a gastric band fitted: "Obesity is a massive societal problem and people do need support. Bariatric surgery is not for everyone, but it’s a tool to help you change your life. It helped me to lose weight, and return to exercise. Now my patients don’t even recognise me I’ve changed so much." Chris has since lost 170 pounds and completed many impressive challenges, including triathlons and cycling from Land’s End to John O’Groats. Having conquered the UK, he and his daughter have gone on to complete an amazing challenge for WaterAid in America.