I must say that the half step was used in the days of 5 speed freewheels (that I am still riding)hehe.......It gave us a full ten gear ratios rather than 6 or 7 distinctive gears. With todays 8,9,10, and even 11 cog hubs the real need for half step has pretty much evaporated. I don't really see the need for half step today. If one is using a really wide ratio cassette like a 11-34 the half step might be of bennefit. 3 chain rings were rare back then as well. I really like the 3 chain rings here in the hills of TN. Good luck with your project and I wish you well. Let us know how the half step works out.
I still love half-step and use it on the UO-8 (45-42/13-15-17-20-23-26) and Capo #2 (49-46/14-16-18-21-24-26), but most late model spiders put the rings so far apart that the chain falls between the teeth.
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"Far and away the best prize that life offers is the chance to work hard at work worth doing." --Theodore Roosevelt
Capo: 1959 Modell Campagnolo, S/N 40324; 1960 Sieger (2), S/N 42624, 42597
Carlton: 1962 Franco Suisse, S/N K7911
Peugeot: 1970 UO-8, S/N 0010468
Bianchi: 1982 Campione d'Italia, S/N 1.M9914
Schwinn: 1988 Project KOM-10, S/N F804069