The average speed for a ride, without stopping is approx. 12 km/hour. For example: the trip from Cavaillon to Apt (about 50 km) can be done in 4/5 hours. The complete Luberon circuit takes around 5 to 7 days.
Yes, if they are over 8/10 years old (according to your habits). A child can ride 30 km a day with many stops. Younger, we advise you to hire a third-wheel, a baby seat or a trailer.