Frame materials play a crucial role in the performance of electric mountain bikes. Aluminum frames are lightweight, durable, and offer a good balance between performance and affordability. Carbon fiber frames are lighter, stiffer, and provide better shock absorption, resulting in a smoother and more responsive ride. Steel frames are known for their strength and durability, making them suitable for rough terrains. Each frame material has its advantages, and riders can choose based on their priorities in terms of weight, performance, and budget.