Originally Posted by
Phil_gretz
I answered a bored "no" to this question. Here is a chart that approximates the gear-inches for two of my road bike setups. Someone please explain to me why I would want to/need to use my big-big combination in favor of dropping down to the middle range of my lower chainring. Please?
Short, sharp-ish hills in a race is the classic scenario; I've dropped a chain trying to shift in the front under torque, while rear derailleurs just go shift. Being in the big ring also makes it quicker to accelerate over the top, too. On the other hand, the penalty for going big-big, assuming your chain is long enough and your trim works is basically negligible, and doing 30 seconds of big-big now and then isn't going to meaningfully affect chain wear.
If I have a long climb or I'm doing it in a leisurely style, of course, small ring, but that's not always the case.