Can't you just pull the crank, put a chain guard on in place of the big ring, pull the small ring and use the FD as a chain catcher. Then pull the front shifter and cable to the FD (just set the limit screws) and you'd be good to go for the cost of a chainguard? Am I missing something vital here (besides you not wanting to look like you'd kludged it together - something I don't care about)?
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Bikes: 1996 Eddy Merckx Titanium EX, 1989/90 Colnago Super(issimo?) Piu(?), 1990 Concorde Aquila(hit by car while riding), others in build queue "when I get the time"