When Ralph and Pat Wanner retired at 50, they didn't choose the expected RV lifestyle. Instead, they embarked on an extraordinary plan; an 18,000-mile bicycle journey from Alaska to South America, a feat that would test their marriage, their limits, and their will to survive.From Arctic tundra to tropical jungles, this couple faced:Polar bears stalking their campsite in Alaska's midnight sunTreacherous navigation through Mexico's Copper Cany...