I believe it was Nervar who made the crank-chainring-chainguard ring sets for Schwinn... not TA. At least that's the set seen here:
http://www.flickr.com/
Could Andy's TA set have come from a different Schwinn model, or one dating from different year than the one seen on the bike shown above?
For that matter, I don't recall seeing any of the "smaller" (intra-chainring) guard plates in any Nervar catalogs - only the larger diameter outer guards for 52 or 54 tooth outer rings are shown. Maybe Schwinn had (wisely) thought that Americans would tend to shift sloppily and jam up their chains between the chainrings. So perhaps the Nervar sets were specially contracted parts and used exclusively on Schwinn bikes?
The TA chainguard rings were available for cyclo-cross (in matched pairs only) and sized for specific chainrings ranging from 43 to 52 teeth. And, they were indeed attached to the large outer borings of 152 mm. as is the case on Andy's example. But, that chainring set appears to have one of the largest and one of the smallest sized guard rings attached. I also don't recall seeing TA chainrings drilled for BOTH the larger guards (or chainrings) and the smaller BCD chainrings, too.
http://www.flickr.com/
The TA guards are not shown in any TA catalogs as being individually available. And there are no notations suggesting that this sort of configuration was offered by TA as a factory available chainring or crankset option.
Was the middle guard ring really even necessary? I've never had problems shifting between quite large ring size gaps. TA had simple spacers (12 mm diameter washers) of different thickness which they more easily could have supplied, if there was a perceived shifting problem.
Still has me curious...
BOB HANSON, ALBUQUERQUE, NEW MEXICO, USA