The more demanding the terrain, the more important the contact point between foot and pedal is. Only when you have a secure footing, can your legs be used as natural suspension. The right shoes play a major role in effective pedalling, and it's also important to be able to walk comfortably when in the mountains. Both clipless pedals and platform pedals can be great options when paired with the right shoes, providing a great bond between bike and biker that can also offer much better power transmission, especially with stiff shoes and spd pedals. Platform pedals and shoes provide more flexibility, freedom of movement and are more comfortable to walk in.