As as rule, there is a minimum amount of skills that you need to possess to be able to join most of the tours (unless stated otherwise).
You need to be able to:
-manage your bike on the road – turn, brake, manoeuvre around any obstacles
-mount and dismount with ease
-use clipless pedals
-use the type of bike that the tour is designed for: if the tour is a Road tour then you need to have experience of riding a road bike
-ride in a group of other riders: this can differ from tour to tour as well as the size of the group per tour. Guidance, on how to ride in a group, will often be provided but as a general rule, you should have basic group skills to keep yourself and your fellow riders safe on the tour.
-you need to know and understand the traffic laws of the area and always ride in accordance to these laws.