Originally Posted by bulgie

The triplizer ring underneath in the OP pic is a Mikkelsen. I goes on a 144 mm double crank and gives you 6 holes to mount a TA Cyclotouriste granny ring.
Those are rare and wonderful things, as opposed to the Vuelta which is a commodity item, good quality but commonplace.

The Mikkelsen design dates back to before the invention of the 74 mm 5-bolt bolt pattern, which originally came on Sugino Aero-Tour or AT cranks. Before the debut of the AT, there weren't so many good choices for the granny on a triplizer. Bernie could have used the Stronglight 99, but that only went down to 28t, vs. 26t for the TA, plus the TA had better selection and distribution.