I'm extracting one question from a multiple-question post of mine elsewhere. What are the downsides to using a 3x STI on a 2x (compact double) setup? I'm currently a downtube shift man (loud and proud, since I bought this bike in 1976), but I'm switching to STIs, without ever having used them myself. Wondering if I can use a shifter meant for a triple on a double, and if it will bug me for years for doing so instead of just getting one meant for a double. Great deal on a Shimano 3x is tempting me. I could get a Nashbar pair meant for a double for the same price, but I'm tempted by the big discount on the Shimano 3x, but only if the downside isn't too great. Please advise. Thanks.