My local bike club's rides are typically for riders that can do a minimum 25-30 miles at a "15 mph on the flats" pace, or faster.
But they have a few rides that really are designed for new riders or riders that want a slower, shorter ride. Here's a few examples from last year's email ride postings. So, check with the local bike shops or cycle clubs. They may have something similar.
Example 1:
This ride is for those that ride at or below 12 MPH Avg..
We are meeting at Loveland bike trail and be ready to leave by 10am, we are meeting at the restrooms for a 22 mile ride, we ride at the slowest persons pace. It is going to be a hot ride so bring lots of water and there is a chance of rain so if it is raining at the time of the ride, the ride is canceled.
Example 2:
...the ride will go to Winton Woods and back. This ride time is A CASUAL-CHCC Ride. Speed at lowest of group (usually less than 12mph and less than 20miles) Record Low to date average ~6mph including stops. It is a no race & no drop ride! Meet behind the College Hill Coffee Company.