I have an older schwinn roadbike frame that looks like its from the 70's or maybe the 80's. The serial number is on the bottom of the bottom bracket sideways. I checked schwinn serial number websites and apparently my bike frame doesn't exist because it starts with an I. My serial number is I702756. Before I had it powdercoated it was like a maroonish brown and yellow. Please help me figure out what frame this is.