What gear configurations or component combinations would you suggest for a gravel bike to achieve the perfect balance between durability, efficiency, and versatility, considering the varied terrain and conditions that gravel riding often entails, and how would you prioritize these factors when selecting components such as wheels, tires, cranksets, and derailleurs, given the constraints of different budgets and riding styles, and are there any emerging trends or technologies that could potentially revolutionize the way we approach gravel bike gearing and component selection in the near future?