“Cast wheels, as found on most standard road bikes, are made in a low pressure cast by forcing a liquid metal into a die. This creates a good initial shape and requires very little machining to turn into a final product, making it ideal for mass production.
“The problem is the metal’s grain, which gives it its strength, isn’t very uniform so more metal is needed to ensure durability, which is why cast wheels are so heavy. Forged wheels are pressed out of lumps of high quality solid metal, pre-heated to a semi-solid state before being pressed into dies then finished on CNC lathes and mills.
“As the metal is pressed into a die in a semi-solid state its grain is more aligned and more consistent, giving it a great deal of strength. It means lighter sections are machined which are strong enough to take all of the forces created by an accelerating and decelerating motorcycle even in high stress areas, which is why forged is lighter – and more expensive than cast.”