So, I've not had a road bike since I was about 16 which is too many years ago to want to remember so forgive my ignorance.  I can remember that cannodales were said to be good back in the day so I've bought one reasonably locally, it was a fixer upper so reasonably cheap. I noticed having got it home that where the paint had chipped the colour underneath was a different colour. What's more it looks like a bit of surface rust. Alarm bells are ringing. I'm wondering what I've bought. I've spent hours trawling the internet but failed. This bike is said to be at least 20 years old. The bottom tube is a tear shape slightly larger than the other tubes. The other thing that makes this stand out for me is that the top tube has rolled at both ends slightly but 90 degrees from the other end. This means when you look at the bike from the side the top bar looks thinner, has a lower profile where it attaches to the head tube. Where as the opposite where it joins the seat post tube so from side on it looks wider, if that makes sense. The aerial number is S followed by about 7 or 8 digits and runs from back to front on the crank drive side. 

Can anybody put me out of my misery please.