Terminal cancer sufferer Jane Tomlinson is "hanging on by her fingernails" as she battles her toughest week of her epic charity ride, her husband says.
Only will power is keeping Jane going on her epic charity ride
Mike Tomlinson said his wife Jane, who is attempting to cycle 4,200 miles across America, is suffering severe pain in her back, hip and pelvis.
Her weight has plummeted during the first 2,500 miles of the trip, he said.
But messages of support from other cancer patients were helping the Leeds mum get back in the saddle each day.
The mother of three said: "My disease is causing me a considerable amount of pain in my lower back which is making the cycling increasingly more difficult.
"This week there have been some sharp, severe climbs which has put stress on places where I am in the most discomfort."
Mrs Tomlinson has now passed the Mississippi River and Route 66, and is aiming to reach New York by 1 September. She plans to stop immediately if that does not happen.
She said: "The futility of the trip is not lessening with the miles that have gone, especially knowing that I've another 1,500 to do in the next three weeks.
"I often wonder why I'm here, what good it can possibly be doing putting myself through this, not being sure that we are raising enough money to make a difference to people's lives.
"Then this week, at the lowest moments, there have been numerous messages from fellow cancer patients saying what we are doing is helping them stay alive, or live their lives, so I know getting on the bike each day is the right decision."
She and fellow cyclists Ryan Bowd, 27, and Martyn Hollingworth, 40, plan to reach Cincinnati, Ohio, by Friday.
Mrs Tomlinson's husband Mike, 45, is following the riders in a support vehicle with the couple's nine-year-old son Steven.
Mr Tomlinson said: "This ride is now a matter of how far her indomitable spirit will take her, her body is causing so much distress it's only this huge mental strength she has that's forcing her to get up each day and mount the bike."