When Black Turns Purple – Hope Rotor Content

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  • When Black Turns Purple – Hope Rotor Content
  • andyl
    Member

    the colour in the anodisng is basically a dye in the aluminium oxide so it was probably not quite anodised right and UV/water has had an effect. Don’t know enough about the dye-oxide interaction to comment any further.

    jonnyb1972
    Member

    My hope hoop wheels are the same

    discoduck
    Member

    Mine haven’t gone purple “yet” but my disks have gone rusty !

    Been out twice since fitted new, once at Dalby where I noticed it the day after that first ride then again after my Peaks ride on Fri afternoon ?
    All orange surface rust in the holes and the inside and outer edges ?

    When I was rebuilding my Dialled Alpine after the re-spray I put new Hope floating rotors on my wheels (Hope hubs DT rims). Both the spiders/holders were black anodised when they went on, but for some weird reason the rear one has turned purple. I haven’t cleaned the bike, so no chemical have been near it, and I have only been riding around the North Downs/Surrey hills, so there’s been no huge heat build up, so I am at a loss to know how this has happened. I will send it back to Hope in the fullness of time, but does anyone on here have any ideas how it could happen??

    baznav73
    Member

    Long spells in direct sunlight can bleach anodize funny colours, know people who keep bikes in conservatories and ruin their anodize.

    I would say it’s probably not sealed properly. Most places will use a metallic based dye for black that is pretty colour fast, I know we do. If the anodic film isn’t sealed properly after dyeing then the dye can leach.

    Must be a faulty part. Hope anodising seems to last forever – afer 4 years the red hubs on my Blur were only very marginally lighter than the new red floating rotors I put on.

    Send it back for instant, so fuss replacement

    All orange surface rust in the holes and the inside and outer edges ?

    More likely metal from sintered pads tranfered to the disk.

    Most (automotive) brake disks are steel or cast iron as it has a very high coefficient of friction, MTB’s use stainless for some reason, possibly strength.

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