Super-cyclist: 78-year-old Montana woman Ethel Macdonald has been tour cycling since 2003, and estimates she's covered more than 10,000 miles across Europe and the US.
Stoneybatter, Dublin: CNN caught up with her during her summer tour of Ireland. She met her Dublin host, Grania O'Hare, through Warm Showers, an online community for touring cyclists and hosts.
Guest book: MacDonald keeps photos and notes from all her guests and hosts. She says she's met close to 400 fellow travelers at home and abroad.
Missoula, Montana: MacDonald's home town of Missoula is a popular destination for adventure cyclists.
Netherlands: The Netherlands is MacDonald's favorite country for cycling. In 2015, Amsterdam launched the Yellow Backie bike lift scheme as an innovative new way for tourists to see the city.
Germany: German "drivers are so aware of cyclists and so polite," says MacDonald. Berlin (pictured) regularly appears on lists of the world's most bike-friendly cities.
France: A former French teacher, MacDonald started her European tour cycling in France. "The whole Atlantic coast [including Bordeaux, pictured] is really good biking," she says.