Google isn't supplying anything useful so thought I'd pop the question to those who may know from experience. I have a short cage Shimano 105 derailleur (happens to be an older 8speed model) that I'm putting on a bike I'll be building up this winter/spring. I'm trying to decide on my rear cassette gearing and want to know the max difference in teeth that the derailleur can take up slack for. Front crank is a 52/39 and wanting to put a 11-28 on the back (sissy gearing I know, you don't have to say it )

Thanks!