When bikes were first conceived, they had steel frames. Knowledge improved, and aluminium bikes rose to fame. They were foreshadowed for their lightweight yet robust potential. The latest development in frame constituents has been carbon fibre. It's lightweight, inflexible, and can also be moulded into a tube shape. Gravel bikes are a new wonder (some may even say stunt). Their admiration is due in large part to their flexibility. Want to ride the road? Pump up the tyres, and off you go. Want to ride that slippery little trail across the moor? Go for it. Need to know what you might encounter along the route? A carbon gravel frameset will be fine.