We set this up on flat ground until they got used to it, and now, we have it on the top of the hill and they have a longer, thrilling ride.  Best ages are from 2-6, and, with many children, instead of purchasing a 2nd car, the children wait their turn on numbered poly-spots(circles)at the bottom of the coaster. It is organized and fair.  My children are 41/2 and 16 months, love this ride and their friends do too!* It was easy to assemble.  Just don't forget to put washers on both ends of the screws!!!