I had a lot of what looked like the same stuff on my Bob Jackson when I got it in December. I generally have Mineral Spirits and Muc-Off (from my LBS) on my workbench. I'm not sure which one or if it was a combo of the two that took care of it. I just remember it appeared nasty and I was really worried that it was going to be tough to get off. My problem was all over the drive train, hubs, the BB, chain stays, and the rest of the lower end of the frame. So it was prevalent, but whichever of the two took care of it quickly. I think it pretty much dissolved and wiped off for me.