While small, Kelleys Island has a surprisingly good trail system, along with scenic & quiet country roads with vistas of the lake. A great place to start mountain biking is the East Quarry Trails with access off Monagan Road just north of the air field. This network of trails loops the old, overgrown quarry area and runs through recent growth forest. The Kelleys Island State Park also has numerous old double-tracks looping another quarry and has several other trails that may be open to biking (check with the local rangers).
To reach Kelleys Island, use the Newman Boat Line from Marblehead.
Overall, East Quarry Trails is the 1st most popular mountain bike trail of all 24 mountain biking rides in Ohio.