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Hollowtech cranks

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  • May 2, 2016 at 12:05 pm #25680
    Mike9_LO

    Can someone explain to me if/how a hollowgram crank is as strong as a solid aluminium crank?

    For example a Shimano 105 hollow crank is supposed to be lighter and stronger than say a Shimano sora which is a solid crank or 2 piece construction as Shimano state on their website.

     

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  • May 4, 2016 at 12:09 pm #871105
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    TypeVertigo

    Just a slight correction:

    Just a slight correction: “Hollowgram” doesn’t refer to Shimano at all. That’s a name Cannondale uses for its own cranksets. If anything, FSA make their chainrings.

    “Hollowtech II,” now that’s the Shimano moniker you were looking for.

    @cyclesteffer

    I believe you’ve described the process of forging. The heat works with pressure to make the metal grains line up in a single direction. The same process is used in the automotive industry for boutique wheels.

    May 3, 2016 at 11:18 am #871103
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    Stef Marazzi

    Shimanos more expensive stuff

    Shimanos more expensive stuff is heat treated – e.g. the metal is “cooked” in an oven, to line the grains in the metal up in the same direction. Thats also how they make thin aircraft engine blades, incredibly strong yet light, and hollow.

    May 2, 2016 at 8:59 pm #871101
    0
    gmac101

    Any beam has to resist

    Any beam has to resist bending and shear forces.  Shear forces (up and down or cutting forces) are resisted by the cross section of material.  Bending is resisted by the material that is at the edge of the beam, so the material at the centre of beam does very little to resist the bending forces.  As bending forces are generally much larger than the shear forces having the material as far from the middle of the beam is the most efficient way by weight to resist the forces, that’s why hollow beams are lighter and stronger.  

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