Dynohubs under water

Discussion in 'Cycling Archive' started by Matthew Vernon, Jul 9, 2013.

  1. Hi,

    Having moved from somewhere with contours to keep the water away to
    somewhere flat and wet, I'm thinking about flooding.

    Obviously if I cycle through water deep enough to inundate the contacts
    on my dynohub, then my lights will go out[0]. But will the dynohub be


    [0] mod capacitors
    Matthew Vernon, Jul 9, 2013
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  2. Matthew Vernon

    Owen Dunn Guest

    The Schmidt instructions for SONdelux dynamos say that the hub should
    never be immersed in water, so I'm guessing they're not designed to
    cope with it. How much they'll be damaged by it probably depends how
    often you go bike snorkelling...

    I did find a youtube video of a submersible dynamo but no actual
    corresponding product:

    Owen Dunn, Jul 9, 2013
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  3. Matthew Vernon

    Danny Colyer Guest

    My commute used to include a section that was prone to flooding. There
    were a few (perhaps 3 or 4) occasions when my SON would have been
    submerged for a distance of a few feet. Despite that, it continued to
    give several years of trouble-free service before I sent it back for new
    bearings after 24,000 miles.

    I was never happy taking it through the floods, though. I think if I
    was expecting to ride through floods on a regular basis then I'd use a
    hack bike with a battery light (or maybe just keep an old pair of wheels
    that I don't care about for the flood days, but still use a battery light).
    Danny Colyer, Jul 9, 2013
  4. I believe it's quite tricky to dismantle/clean/lubricate some dynohubs
    without damage, and if water gets in it's likely to reduce the long term
    effectiveness of supposedly "for life" lubrication.

    I wouldn't expect any immediate electrical damage. A shorted dynohub
    doesn't have that high a saturation current, and even dirty water won't
    be an especially good conductor.
    Alan Braggins, Jul 9, 2013
  5. Matthew Vernon

    Clive George Guest

    Not obviously at all. Water doesn't conduct as well as copper, so
    provided the path of least resistance is through the light, it will
    still light up.

    And indeed it does - they work when they're underwater. First learned
    with a BB dynamo, with the light underwater too, gently glowing away (I
    was going very slowly...).

    The dynohub doesn't instantly die when you do it either, but I do wonder
    if my bearing replacement intervals have been shortened as a result of
    enjoying riding in floods. The electrical gubbins haven't suffered.
    Clive George, Jul 10, 2013
  6. I'm assuming it wasn't a handlebar mounted light, and I wouldn't ride through
    a flood that covered a fork crown mounted light, but just how high/low was it?
    Alan Braggins, Jul 10, 2013
  7. Matthew Vernon

    Clive George Guest

    Fork crown mounted, and it was lapping at the underside of the
    horizontal bit of a set of drops on a 23" frame. That remains my record
    depth flood riding :) It was night, but I was wearing a headtorch. I
    also took the pannier off.

    There was no current - I've had amusement on shallower water (still over
    hub depth) when going past gates and catching the flow.
    Clive George, Jul 10, 2013
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