The shifter seen on Mattie's Jack Taylor tandem is a standard Campagnolo Gran Turismo shift lever
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I sold a few NOS shifter/derailleur combos a few years back in their original boxes. A friend who used to work at Campagnolo back in the day said that they were designed so that it was far less likely that the user would accidentally shift the derailleur (especially by women riding with skirts). The Gran Turismo derailleur was most commonly used in Italy on sporty or city bikes with only a rear derailleur. These bikes needed to be dummy-proof, and this is what the combo of protected lever and boat anchor Gran Turismo derailleur offered. The GT derailleur may not have shifted overly well, but it could be installed, adjusted once and it was set for a lifetime of use. You could submit it to heaps of abuse that did not detract from its function. Compare this to the standard Suntour, Shimano, Simplex and Huret derailleurs that would frequently go out of adjustment by a minor fall of the bike, and wear out if you rode the bike with the derailleur set between two gears.
Steven Maasland
Moorestown, NJ
USA