Just by point of clarification, I don't think they literally mean "rail bikes", but a bike trail on a former ROW.
Yonkers rail bike trail nearing construction
Groundwork Hudson Valley got $394,000 in 2015 from the state Regional Economic Development Councils for a trail along the former Getty Square spur of the New York and Putnam Railroad
Groundwork Hudson Valley and the City of Yonkers are putting the finishing touches on a plan to connect Caryl and McLean avenues with a half-mile trail that would run along a former railroad line that once connected Getty Square to a defunct railroad in the Bronx.
Construction is expected to begin in the spring, and the goal is to promote bicycling and provide an amenity to the neighborhoods along the new trail.
The southwest Yonkers rail trail is separate from the South County Trailway that runs from Van Cortlandt Park in the Bronx through Tibbetts Brook Park in Yonkers to Greenburgh. The South County Trailway will be accessible from the southwest Yonkers rail trail because the new trail will connect to existing paths in Van Cortlandt Park at Caryl Avenue that lead to the Putnam Greenway, New York City's name for its section of the South County Trailway.
The first phase of construction will stretch from Caryl Street to McLean Avenue and will include the new park by Lawrence Street partly funded by the Impact100 Westchester group. The vision for the park is to have a children's playground and a community garden, along with the trail.