The TA 3 pin crank can be made into a triple. The smallest ring is a 36. TA makes triple bolts for it. They even made track rings for it. I saw a inch pitch ring for one somewhere. It might have been at Bicycle Specialties in Toronto. That's a good place to go for TA parts anyway. By the way, these rings will fit on Campy Gran Sport also, and were made in many more sizes than Campy, so you can replace silly crossover gearing with a proper half-step. I just remembered, I've seen an Alex Singer with a Trois Attaches triple, so they were used on good bikes too.
Leonard Bulger Ann Arbor, MI
Gazelle with Pro 5 Vis triple BSA with Trois Attaches 1/8" track Heron with Steel Sport crank arms and TA Criterium rings (due to be replaced with Alloy Sport with triple 3 Attaches rings) Franche-Comte with Pro 5 Vis double Follis with mismatched cottered steel crank and Cyclotourist double rings Wife's Trek 720 with Pro 5 Vis triple Citroen TA