You can pick up the path at various points, but one that is near a few of our recommended hotels is near the Hyatt Irvine (1/2 block south) off of Main Street. Look for the bridge and you'll find the path on the south side of the dry creek.
Mountain bike trails are available along the coastline. For the most part the paths are flat, but for a leisurely scenic ride they can be fun. Visitor center map shows the exact location of the trails (or look online).
Newport Back Bay Route. A beautifully scenic and mostly flat route for those staying in/near Newport Beach:
* Pick up the route on either end, but our mileage starts from the intersection of Jamboree Road & Back Bay Drive
An approximate 5K loop that runs along city roads on crushed stone paths and partly along the paved San Diego Creek bike path. Trails are inside the loop, but be sure to have a partner if running through the trails.
This route is from fellow athletic-minded traveler and stud triathlete, Mike Collins: North on PCH to Huntington beach or even up to Long Beach is a good flat ride. You must get an early start to avoid bad traffic on weekends.
Another recommended route from OC resident and stud triathlete, Mike Collins: Santa Ana River Trail goes inland from the border between Huntington Beach and Newport Beach for about 30 miles with no traffic.
People watching is pretty good along this run that heads south from Newport Beach Pier to Balboa Pier (or vice versa). Flat run on hard surface.
Located in downtown Fullerton, about 25 minutes from Newport Beach, this indoor cycling studio provides a nice excuse to go exploring (should you have the extra time). Free street parking is available around the studio. Locker rooms have showers and lockers for personal items.