The bikes belong to Beth and Kayla Adams.
Their father, 43-year-old Christopher Adams, was killed in a car crash in May 2014 in north Fort Worth.
He left the bikes to his daughters, and they've continued racing in his honor.
But on Jan. 8, Tarrant County records show the bikes were stolen from Village Creek Motocross, where they were locked up and being stored. Two other bikes, an 18-foot trailer and some tools were also taken.
One of the bikes says, "RIP Daddy," and has their father's birth and death dates on it.
Beth posted pictures of the bikes on Facebook. It was shared 200 times, and the next day, she got a tip – a picture was posted on a woman's Facebook page advertising the bikes to sell, but law enforcement officers haven't found the woman.
"Still to this day, they can't do anything about it because it's just possession of a picture pf stolen bikes," said Beth.
It's now been six weeks with no leads.
Beth is offering to not press charges for the bikes' safe return.
"Those bikes are priceless," she said. "Someone could offer me a million dollars and I wouldn't sell them. They're irreplaceable."
A GoFundMe account has been set up for the Adams sisters at http://www.gofundme.com/jxv4gk