"The trouble with light rail and subway, some say, is that it only serves a small area around each station, and that vast areas can be left to dependence on cars. Planners consider mass transit service areas around light rail stations and subway stops to be about 1/4 mile - any farther and you'll see significantly diminishing interest in making the trek.
But that's for walking - and not biking.
A Rails to Trails Conservancy report from earlier this year addresses this very issue, noting that 'bicycling in particular has great potential to allow more people to access public transportation conveniently. Accessing public
transportation by bicycle can shorten travel times significantly. Because bicyclists travel about four times as fast as pedestrians, convenient access by bicycle can increase the geographic area served by one transit station 16-fold.'"
The article describes how places such as Minneapolis and Dallas are expanding transit service areas through trails.