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Motorcycle News (UK) - - This Week - CHIEF DE­SIGNER AT DYMAG Mike Wil­son

“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.”

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