Juego de bielas tándem vintage TA Specialites 170 mm 34-49-54 rosca francesa T.A. Bicicleta
All are 170mm, ISO square taper, and feature 14mm French pedal threads, not all of which are pretty, but I was able to thread the appropriate side into all. Well used T.A. Specialties tandem bicycle crank arms and chainrings.