This bike looks to be a Trek size 56, which is
54.9 seat tube c-c and 55.5 top tube c-c
Catalog with geometry chart on next to last page is here.....
http://www.vintage-trek.com/images/t...TrekRacing.pdf
I have two of these in different sizes and I ride them more than my Italian bikes (except for the Tommasini), which is why I have downsized a lot.