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  • Cannondale carbon fork expander alternative.
  • mastersweeteater
    Free Member

    After some advice regards expander plugs;
    Caad12 with standard carbon fork, comes with a cannondale/fsa superlight si expander plug/bung
    The length of the actual plug itself is very small and makes me feel a bit uneasy about the support offered to the fork/stem, from the bung. I know it’s been designed by professionals, but I would like something a bit more traditional in length so it rungs the full length of the stem.

    I am looking for an alternative, however the problem is, the wall of the carbon fork is thicker than most, probably to compensate for the small length of the expander plug. So all the plugs I have tried won’t fit! Tried a couple of no name brand and a spesh one. All too beefy. Any suggestions would be great. Ta in advanced.

    mastersweeteater
    Free Member

    Just for peoples future reference anyone looking for an answer to this topic:
    Deda expander plug did not work, too thick in diameter.
    Colnago Expander Plug: worked a treat! A good length that goes well below the stem and top headset bearing. Also allows use of a “normal” top cap.

    Milese
    Free Member

    This is a rare post where people are buying things they dont need to add weight, not take it away!

    Have you any examples of steerer tube failure due to inadequate bungs?

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    jameso
    Full Member

    The length of the actual plug itself is very small and makes me feel a bit uneasy about the support offered to the fork/stem, from the bung. I know it’s been designed by professionals, but I would like something a bit more traditional in length so it rungs the full length of the stem.

    I am looking for an alternative, however the problem is, the wall of the carbon fork is thicker than most, probably to compensate for the small length of the expander plug.

    A longer bung may not be required if the steerer is thicker. The whole idea of a bung stopping the steerer from deforming is questionable unless you’re sure of the right length – a bung creates a rigid ‘stem’ inside the steerer that is clamped by and stays aligned with the stem. If it extends much below the stem, and the steerer is thin (ie flexible) enough that it needs a long bung to begin with, it follows that the bung lower edges will be putting pressure on the inside of the steerer as the steerer flexes when you lean on the bars. Some of those edges can be sharp or they might cause wear as they move. That’s potentially not a system I’d want to ride.

    In this case a thicker, hopefully stiffer steerer won’t flex so much so it won’t matter. But in general I’d just stick to what the brand recommends unless they’ve also tested and ok’d the combo you’re looking at using.

    It’s daft really, there’s stories about how in the old days they’d hammer a broom handle down road race bike steerers to back them up. And here we are in 2022 watching fork recalls pop up a few times a year and we’re still not fully confident in one of the most safety-critical parts of a bike despite all the material and manufacturing advances. I digress, but it does seem daft.

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