Correction: the Simplex catalogues say the Simplex lever front derailleur covers 28 to 52 chainring range, and I'm using it with 28-53 chainrings on my Mondia. I have observed some different front derailleur cage lengths so that's a caveat, and the deeper derailleur cage as illustrated in the catalogues is needed for a greater difference between chainrings. Simplex and other old catalogues are available through Chuck Schmidt's Velo Retro site, and are useful for information on older parts such as this in Jerry's inquiry.......Peter
Jerry, regarding your question about the chainring range of a lever front derailleur, the Simplex catalogue (and The Dancing Chain book) both say that the Simplex lever front derailleur covered 26 to 52 teeth. Here I'm running one with 26 to 53 chainrings on my Mondia, and it shifts fine, even being one tooth over its spec .
http://www.peterbrueggeman.com/
Peter
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Peter Brueggeman
La Jolla California USA
4peebee(at)peterbrueggeman.com