re 8 vs 9, yes it is only 1 more, but your example of 8sp 11-32 and 9 sp 11-32 is one I am familiar with. In our household we have both and all I can say is that when you ride bikes that have closer ratios, you really get to like it.
the 8sp 11-32 has a 20% jump in there, between the 15t and 18t, which is a big jump. I rode a 8sp 11-28 for a long time and now have a 12-25 on that bike, with a 12-13-15-17-19-21-23-25 which has closer % between shifts, which is just so nice.
I realize that a 12-25 isnt much use while touring, unless its on a bike with a 42/32/22 which gives a 22 g.i. low, but really my point is that having closer jumps is always going to be attractive and has real world advantages, easier on the legs and knees, nice in headwinds or long drawn out climbs where sometimes you are too high, then too low.
I guess I look at increased speed in back as a real plus, and for me having closer ratios are a priority and a real world advantage for my legs when you have a bunch of extra weight on a bike in a touring situation.
As I've gotten older and more gearing nerdier, I'll prefer to have a smaller crankset, but which allows a tighter cassette for the vast majority of riding speeds, in the 15-25kph range--as this is where it will be easier on your legs and knees and you will be faster overall at the same time (but still having a crucial low gear inch that of course depends on your load and terrain you'll be in).
here are three charts of three bikes in our household with various gearing setups, specifically look at the percentage jump between shifts.
I agree with you on the tight spacing being very nice. But while touring, 90 percent of the time I am in the range of 50 to about 90 gear inches, thus I want to have the really tight gearing in that range. I need the low gears for hills, but I am content to have wider gear ranges on the hills because I spend so little time in those lower gear ranges.
I use a 52/42/24 road crank. The 52 and 42 gears are almost exactly one and a half step gearing plus the 24 granny. I do not use the two most cross chained gears on each chainring (when on smallest chainring, do not use the two smallest rear cogs, when on the middle chainring do not use the smallest and biggest cog, etc.). Thus, my 8 speed cassette with a triple gives me a total of 18 gears.
This graph is my 18 gears plotted up using Schwalbe 559X40mm plain Marathon tires. The key on the right shows which chainring is used for each gear. The numbers are gear inches.
I did one tour with a 46T outer chainring instead of the 52 to try half step gearing plus granny. That is graphed below. This gave me one more gear in the gap of 51.1 to 59.6 and I lost a little on the high end.
Around home I prefer the 52T outer chainring over the 46T, those two highest gears above 110 gear inches are really nice on long shallow downhills. But for future touring I expect to switch to the 46T outer chainring because I like to have that extra gear in the gap between the 51.1 to 59.6 gears. And when touring with a big load in my panniers, I am less likely to fully enjoy a fast downhill ride, thus while touring I rarely use the two highest gears of 110 or more gear inches.
I did this spreadsheeting and graphing myself because I wanted a way to graph up different gearing without including the cross chained gears. Everybody else's spreadsheets for gearing included the cross chained gearing.
I mentioned that I do not use 6 of my most cross chained gears, but by coincidence, I find a lot of redundant gears (duplicates) in those gears too, so by limiting myself to oly 18 of my total of 24 gears that I am not losing too much.
First photo is the drivetrain with 52/42/24 road crank with granny.
Second photo is on a different bike, the 46/42/24 for half step plus granny.
