NYSDEC provides a Google Earth map of mountain biking opportunities – and a number of other thematic maps – all available at: http://www.dec.ny.gov/pubs/42978.html. The direct link that opens in Google Earth is: http://www.dec.ny.gov/maps/biketrailslink.kmz
There are a number of other useful maps there, such as public fishing stream parking areas and watchable wildlife locations. Those links show the Google Map versions.
