Residue after riding in the rain?

crescent
crescent Posts: 1,201
edited August 2012 in Workshop
After a couple of rides in the rain (aren't they all at the moment) I have noticed a residue forming around the rear brakes and wheel rim on my bike. I always give my bike a good clean after being out in the rain and it does come off with Muc-off, I just wondered what it is? It has the appearance of a greyish coloured paste and seems to build up on the faces of the brake blocks and then spread itself over the rim. Or perhaps it builds up on the rim and then collects on the brake blocks, difficult to say which comes first.
Any ideas? I thought it might be oil getting thrown from the drivetrain and emulsifying with rainwater.

Cheers
Bianchi ImpulsoBMC Teammachine SLR02 01Trek Domane AL3“When I see an adult on a bicycle, I do not despair for the future of the human race. “ ~H.G. Wells Edit - "Unless it's a BMX"

Comments

  • Garry H
    Garry H Posts: 6,639
    A mixture of dirt/grit, rubber and the alloy from your rims.
  • rolf_f
    rolf_f Posts: 16,015
    Garry H wrote:
    A mixture of dirt/grit, rubber and the alloy from your rims.

    In otherwords DIY grinding paste. It's wearing your rims away. Don't forget to dig the chunks of alloy out from your brake pads as well.
    Faster than a tent.......
  • crescent
    crescent Posts: 1,201
    Yep, that sounds about right. I occasionally use carborundum grinding paste in my job and that is exactly what it looks like.
    Cheers
    Bianchi ImpulsoBMC Teammachine SLR02 01Trek Domane AL3“When I see an adult on a bicycle, I do not despair for the future of the human race. “ ~H.G. Wells Edit - "Unless it's a BMX"
  • Giraffoto
    Giraffoto Posts: 2,078
    It could be a sign that your brake blocks are a bit too abrasive, too
    Specialized Roubaix Elite 2015
    XM-057 rigid 29er
  • JamesB
    JamesB Posts: 1,184
    It could be a sign that your brake blocks are a bit too abrasive, too

    or that UK riding conditions of rain, gritty roads and general yuk make an appalling mess of bike rims and brakes pads :(:(:( , no matter what pads / rim brakes are used. Only in nice dry weather IME is this muck avoided