A Caribou family is sending off their oldest daughter on a 3,300-mile bicycle journey from Portland, Maine, to Portland, Oregon, for a personal cause — her brother’s rare nervous system disease.

Leaving at 11 a.m. Sunday from Harbor View Park in Portland, Maine, Sphen Johnson said she will try to bike 50 miles per day for the next two months to raise awareness and research funding for her brother, Kaleb, who lives with neurofibromatosis, or NF1, a rare, genetically driven disease that causes tumors to grow on nerve tissue.

“It’s something I’ve wanted to do for a while,” 21-year-old Johnson, a 2011 graduate of Caribou High School, said. “Now is an ideal time. I wanted to do this to clear my mind, and I wanted more people to know about NF.”

Johnson is trying to raise $10,000 for Neurofibromatosis Northeast, a nonprofit organization that raises money for research and awareness of the disease, which affects about 100,000 Americans. To donate, visit gofundme.com and search “Sphens bike trek for NF1 awareness.”

Johnson’s parents, Cindy and Chris, who own the Cubby Thrift Stores, are a little bit nervous but also excited that their daughter’s ride is helping their son.

Caleb, 17, was diagnosed with NF when he was 9 months old. He and others with the disease can have a normal life span, according to the National Library of Medicine.

“Although the disease has been around for generations, research only began in the 1990s,” Cindy Johnson, mother of Sphen, Kaleb and three other children, said. “Kaleb has done many experimental drug programs at the National Institute of Health and the National Cancer Institute, and none of them have been effective yet.”

So far, Kaleb’s tumors have not been considered cancerous, but he has had complications and his challenges going forward motivated Sphen to take up his cause.

The bike ride “will be a learning experience all the way,” Johnson said. While she is a hiker, she has not biked much in recent years. The longest trip she’s done so far was about 30 miles, a loop from Caribou to Washburn to Presque Isle and back.

Starting Sunday, she’ll be trying to bike about 50 miles per day, completely solo, couchsurfing and camping most of the way.

Mojo Outdoor Sports in Presque Isle helped get her Trek hybrid street-trail bike ready for the trip, putting new brake pads and a chain on it. She learned how to fix a flat tire, change tire tubes and fix a chain.

Johnson’s original idea was to not really craft a plan but “buy a map every state and go from there.” But her dad helped her plan a route.

She’ll ride west through New Hampshire, Vermont and New York state, with a ferry ride across Lake Erie to Ontario, then through Michigan, the Upper Midwest, the Dakotas, Montana, Idaho and onto Oregon. About 10 percent of the trip will be on trails and bike lanes, her dad Chris noted.

Johnson hopes to fly back to Maine by the first snow in The County, aiming for 60 days but no more than 90.

After the trip, Jonson will be figuring out what to do for the rest of her life — she already has general education college requirements ready to transfer — around the same time her brother Kaleb will be charting his path. Set to graduate from Caribou High in 2017, he has interests in computers, as well as residential construction.

“I think it’s great,” he said of his sister’s journey.

Johnson will be chronicling her journey at portlandtoportland2015.blogspot.com.