Lightspeed - use the large tip on rock. Small hard tips skate on rock, the bigger rubber tips are more like climbing shoes. <img src="/forums/images/graemlins/grin.gif" alt="" />

wish I still had the larger ones, you can break carbide tips on rock. <img src="/forums/images/graemlins/blush.gif" alt="" />
Jim <img src="/forums/images/graemlins/cool.gif" alt="" />
These are my own opinions based on wisdom earned through many wrong decisions. Your mileage may vary.