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So which brake shoes are lighter?  KCNC CB1 shoes or AX lightness shoes?
 
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The CB1s are basically highly machined versions of the basic Shimano shoes.  Hardware consists of Al with a Ti main bolt.
 
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The Ax Lightness shoes are surprisingly heavier.  The shoes look more minimalist and all of the hardware is Al.
 
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The Ax Lightness shoes do have a nice design though, the shoes are designed in a way that the bolts act as ball joints enabling the shoes to pivot under pressure.  This allows for even brake wear and maximum contact area.