Originally Posted by
lasauge
AFAIK "compact" chainrings are a modern concept, since you really need a freehub mechanism that can take a 12 or 11t smallest cog to benefit (on a roadbike anyways), and that excludes any bike with a freewheel. However, you can make almost any crankset "compact" by installing smaller chainrings, assuming the BCD is small enough, see the column labeled "smallest ring" on this chart from the Sheldon Brown site:
Sheldon Brown's Bicycle Crank/Chainring Bolt Circle Diameter Crib Sheet
For an example, consider my '83 Stumpjumper with a Sugino AT crank (110bcd) that's set up as a compact double (48-38 rings). I'm using this crankset this way because I don't really need the very small gear of a triple crank, and this lets me use a narrower BB spindle.
Not that modern. There are a number of different French cranks that are compact; the sugino mighty tour has been around for a long time. Compact cranks have only recently become popular and that is helped no doubt by modern cassettes since you can have a pretty wide ranging rear and have reasonable jumps between your gears. I recently set up a vintage bike with a compact crank:
