I live in Syosset and have ridden to Manhattan several times using the LIE Service Road to Douglaston Parkway to Northern Blvd to the Cross Island Parkway Bike Path and then some back roads to College Point, where I would get on the pedestrian/bike path along the Northern Blvd Bridge. From this bridge, there USED to be a little dirt path that would lead to an industrial area just shy of the Flushing Bay Promenade, which I would take all the way to LaGuardia Airport, cross the bridge over the Grand Central Parkway to Ditmars Blvd, then vary my routes to the 59th Street Bridge (I never did find the ideal one!).

If that little dirt path off the Northern Blvd Bridge was sacrificed during the recent reconstruction, you'd have to brave Northern Blvd a little bit around CitiField.

All-in-all, it was always a fun ride, but not one I'd like to do every day. Fortunately, Syosset has its own RR station, so you can experiment with training to different stations, then riding the rest of the way.

Whatever you choose, welcome to Syosset!

(PS: Two of my good friends own Long Island Village Realty in Syosset and can help you find a place.)