Just to clarify, this is tar that was used to patch a hole in the street and hadn't dried. I avoided it with the front wheel, but the rear got some gunk on it and sprayed a couple of thick strands onto the caliper brake. Doesn't look like any got on the frame or even in any moving parts; pure luck there. First thing I think I'll try is Simple Green, since that's all I have here, but I'll move up from there.