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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??
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.
My hope hoop wheels are the same
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 ?
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.