well , again for us rain is like 30 days a year. So we almost can avoid it and not feel cheated out of lots of riding. I'd say I suspect the red/brown stuff is likely a combination of oil/grease/clay? But rubbing it off , it looks sort of pitted and dug in like. ? It only appears during the few times i find myself in the rain. like today. Left too late.
Yes, four bikes I loose track. took out the long distance tourer today. (Fuji.) Been a long time since bb overhaul. Not sure how much overhaul I will get done before summer on our four bikes.