I've got a fairly old road/racing bike and its rear brakes are responding quite slowly. I've just had it serviced, and the bike shop said it's brake pads are fine..... Any ideas? Could be the cables? Or is it just because the ground has been really wet recently?
Old? How old? Is the rear rim clean and free of any oil film (possibly thrown from the chain in the wet weather/roads you mentioned)?
How close are the pads set to the rim? They should be somewhere around 1/16" clear of the rim.
By 'responding' do you mean the caliper moves slowly in response to the pull of the lever or do you mean the brake is not slowing you quickly enough when riding?
If the calipers are moving smoothly in response to pulling the lever try a new set of pads. If the cable is sliding smoothly, without drag and the caliper pivot points are lubricated and also moving freely the rim surface and pads are the only other variables.
OK, there is some cable stretch to check and caliper arms flex on some cheaper brakes, but I doubt either are culprits in the slow response thing.