Originally Posted by
repechage
The origin of this probably dates back to lever front derailluers, an adaptation bit to bring cable shifting to existing bikes.
My first though, but wouldn't almost all bikes of that vintage have clamp on single shifters anyway?
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1 Super Record bike, 1 Nuovo Record bike, 1 Pista, 1 Road, 1 Cyclocross/Allrounder, 1 MTB, 1 Touring, 1 Fixed gear