Not to mention unnecessary-- my chainline is perfectly straight when on the 6th cog, so there are 5 above and 5 below. It's only 35mm total between the center of the 1st and 11th cogs, so the chain is never deflecting more than 17.5mm, roughly 3/4". Unless carefully shifted, I imagine a triple would have greater amounts of possible deflection. Which is why I don't favor a triple-- above and beyond the duplicate ratios, there are gear combos you simply can't/shouldn't use.
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