I love riding at the pump track too. The one near here is always crowded with people of all ages. I took my son and his friends to ride their BMX bikes last weekend with me on the uni. A kid who was probably three years old figured out that he was faster than me so he would give me a 2 roller head start, pass me at the short cut on the first turn, then come all the way around the track and lap me before the last turn. All that with a big smile on his face. It was also cool to see him get better at riding with every lap. When we got there he was afraid to ride off the start platform. A little while later I noticed him going up and across it without stopping while chasing me.