Join Date: Apr 2009
Location: New Rochelle, NY
Bikes: too many bikes from 1967 10s (5x2)Frejus to a Sumitomo Ti/Chorus aluminum 10s (10x2), plus one non-susp mtn bike I use as my commuter
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For practical purposes consider the spider to be equal to that of a chainring, roughly 4mm. below is the approximate working length of the various bolt options.
Single is long enough for the spider + 1 chainring. 8mm
double is long enough for the spider + 2 chainrings. 12mm
triple is long enough for the spide +3 chainrings + a spacer the width of the spider between 2nd third rings. (5 widths), 20mm
For your setup, if the spider is between the rings, that's the same as a normal double, but if the rings are both on the same side of the spider, you'll need a spacer between them making it between a double and a triple. For that you'll need a triple, but will probably have to file it shorter.
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