Essie thought picking up a bike and riding without her training wheels would be hard but one night she jumped on a bike about the same size as her "trainer" and she starter to take off a bit! So we ran across the street to our park, even though its 7:30pm and dark, and let her try it with some space and grass. She took off! She only needed help with the initial balance and first couple of pumps. Within the next two days she could do it all herself.
The next day I took the kids for a two mile bike ride, some of the route included dirt terrain, she did great! I wish I had more pictures of her, they turned out a little blurry.