By Wednesday afternoon, they were ready for a well-deserved pit-stop and pulled into a fast food restaurant in rural Missouri to re-fuel.
The Duchess of Cambridge's younger siblings were spotted eating at a McDonald's restaurant, tucking into some food with their fellow team mates.
Both were dressed in their distinctive red, white and blue cycling gear – and it didn’t take long for excited locals to spot them.
Pippa, 30, and James, 27, both posed for photographs before loading up their bikes and jumping into a waiting black vehicle, presumably headed for a nearby hotel so the team could get some rest.
On Saturday, the pair joined nearly 300 other cyclists in San Diego, California for the start of the Race Across America, a 3,000 mile charity bike ride.
The Middletons and their teammates will travel through 12 states in eight days, covering between 350 – 500 miles per day. They are raising money for the British Heart Foundation, of which Pippa is now an ambassador, and the Michael Matthews Foundation.
After completing the event, sporty Pippa is auctioning her bike on eBay to help generate more funds. In July, she and James are then heading to Istanbul to take part in the Bosphorus Cross-Continental Race Swimming Race; a 6.5 km swim across the Bosphorus Strait.