If you are looking for some wonderful local road rides we encourage you to click on over to MapMyRide.com. It's a fantastic resource for mapping out local road routes. Whether you've lived in the area all your life or are just visiting for a few days or weeks you're sure to find some amazing local road rides.
The Harrisburg Greenbelt is an excellent place to ride just about any kind of bike, although there are couple gravel sections which are best navigated on hybrid or mountain bike tires.
Here is a great resource provided by the Cumberland Valley Visitors Bureau for some local road and rail-trail routes.
If peace and quiet are your cup of tea, check out the following rail-trail opportunities:
Local mountain biking, weekly rides: SAMBA
Harrisburg Bicycle Club has group rides for various levels of ability.