Originally Posted by budster
I saw a good chart recently about this. Wish I could remember where. But it showed the whole "don't cross the gears" thing very clearly. Basically (for a 7 speed):
- Lowest Chainring: gears 1-3
- Middle Chainring: All gears
- Big Chainring: 5-7
Since I saw that, I mainly just leave it on the middle ring and shift the rear deraileur. On a big uphill, when I drop down to 3 or 2, my next shift down will be to shift to the low chainring; on a big downhill, I'll go up to 5 or 6, and then kick it up to Big. With a little practice it's become second nature.
I really liked budster's response. May I go out on a limb of my own? Even if only to show another perspective. I'm a hill-country Cyldesdale, gearing really matters to me. I've plotted the gear-inches for the various combinations and identified my optimum sequence -- I don't always use it, but I can tell what it is and if I'm deviating from it. Forrester talked about these calculations in Effective Cycling.
The chart below identifies my gear-inch (gi) possibilities and color-codes the sequence I try to use. On my 21-gear bike, there are really 10 pragmatic gear combinations.
You can see that it follows Budster's general pattern. This is a Trek1100 with non-standard cassette and chainrings. The Red X's identify combinations that I can't select because there's not enough chain. You'll also see that the shift from 27 gi's to 39 gi's involves shifting up on the chainring and down on the cassette.
I also really liked HelmetHead's post about Cadence. I just try to produce 85 rpm regardless of slope, and then I move within my optimal shift pattern to stay at 85 rpm.
I hope nobody minds the anal-retentive perspective, but gear patterns and cadence have really helped my riding. I think contemporary bikes are complex machines and if we're going to climb hills and ride distances, maybe the minutae matters. YMMV.