I have to correct Jerry Moos in that Avocet cranks had drillings for a 74 mm. bolt circle, which went to a really low possible gear. I have a 28 toothed Avocet gear on my modified Campy NR crankset. And my answer to the original question regarding 70's triples would be go to a Stronglight 49D or TA w/ TA rings for a true touring set up. The 36 x 32 low gear on the standard Campy triple would be fine for unloaded touring, but wouldn't cut it as well in the mountains with a loaded bike. It's nice to climb a 20% grade relaxed and sitting down, maybe leaning forward to keep the front wheel on the ground. Then again, how many people crossed the country back in 1976 on gas pipe touring bikes with a low gear of 39,40 x 28?
Happy trails,
Dan Artley in Parkton, MD
Archive-URL: http://search.bikelist.org/
The choice may depend on how low a gear you want. The TA Cyclotourist and Stronglight 99 will take about as small an inner ring as anyone is likely to want. Campy made two on-topic triples I'm aware of, the Campy NR triple with inner BCD about 100 BCD and Campy GS triple with 116 BCD. Theoretically, I think the GS should go down at least to 34T and the NR triple to maybe 30T, but I don't think I've ever seen a ring smaller than 36T for either one. Stronglight 93 can be configured as a triple, but the smallest ring I've seen is 38T although I would think a 36T should be possible. Another common On-Topic triple was Avocet/Ofmega. The inner circle is only a few mm different from Campy NR triple, but smaller Avocet/Ofmega rings were made, I think at least as small as 32T.
REgards,
Jerry Moos
Big Spring, TX