I was looking for something with some google searches and found a very interesting article comparing friction on a 1X and 2X system. Not directly comparable to the discussion here, the 2X system had 53 and 39T chainrings. But, some very interesting results on how much cross chaining and sprocket size and chainring size affected friction losses. Both systems were 11 speed. One big result was bigger chainrings and bigger sprockets were more efficient. We all knew that already, but to some degree it was more important than cross chaining which surprised me.
In the big picture, I do not think the friction losses would be noticeable to a non-racer, I certainly can't feel the difference in losing a few watts by having my dynohub powered lights on compared to off. So, if one gear consumed a few more watts than another, I doubt I would notice it. But, I still found it interesting.
Article here, second link is a blow up of the graph:
https://www.velonews.com/2019/05/bik...etrains_493185
https://s27394.pcdn.co/wp-content/up...08.29-AM-1.png
I just did a quick look at 11 spd parts
seems that chains are just a bit more than 9, 10 spd,
some cassettes though are pricey, from 100-200-300 clams each
here's a question--does 11 spd stuff chains, etc, last a LOT less than 9 spd stuff?
We only have one 10 spd bike in the family, so dont even have that experience yet, not replaced the chain yet.
Ive generally gotten about 5000kms out of 9 spd chains, similar or a bit more for 8 spd, similar or a bit more for 7 spd---but of course, drivetrain cleaning, maintenance, how you ride, how strong you are, how heavy you are, ---- ALL play a huge factor in this
-how much does chain angle affect chain life--although Im sure chain condition, ie clean or not, plays a big part here too.
and to finish, I still see my triple 9 or 10 spd as the perfect setup for touring WITH A GOOD LOAD. Mid ring for most of riding, large ring for downhills tailwinds, and granny for climbing.
I use all speeds in back regularly, I use all three chainrings regularly (but not changing chainrings so often its a pain in the rear)
the cost of replacement stuff is not expensive
the few extra pounds (if that) of an extra cable, fd, fd shifter and two more chainrings IN MY CASE, being a light little bugger, is nothing....especially nothing compared to how I use my bike, ie loaded up for long trips, carrying extra food, water etc
My two derailleur touring bikes and my rando bike all share the same Sram eight speed 11/32 cassette (11/12/14/16/18/21/26/32), Rando bike has a road triple with stock rings of 52/42/30. The derailleur touring bikes started with the same road triples, but I changed the inner and outer rings so it is now half step plus granny, 46/42/24. I built up those three bikes, so the component choices were mine alone.
On those three bikes I use the six (out of eight) sprockets that are least cross chained with each chainring, thus each of those bikes has 18 gears, I do not use the full 24 that mathematically exist. And when I built up the bikes I ran the numbers to make sure that all 18 gears were useable and non-redundant without any big gaps.
I am totally happy with 18 gears, do not need more. My folding bike also uses the same eight speed cassette, helps keep my inventory of spares much smaller. (And my Rohloff bike uses the same eight speed chains, makes inventory even more manageable.)
My two year old road bike has a compact double and 10 speed cassette, I bought this bike complete, so I did not chose any of the components that came on it. But I made one change, it had a 13/29 Campy 10 speed cassette, I wanted a slightly higher high gear for downhills so I fitted a Miche 12/29 cassette instead. When you remove the redundant and cross chained gears you end up with about 14 usable gears, the upper seven are on the big ring and the lower seven gears are with the small chainring. I like the bike, I like the ride, I like the gearing, BUT, for the two brevets I rode this year, instead of the road bike, I used the rando bike that I built up with the eight speed cassette and triple because the wider range on that bike works better on the hills on the brevet routes. I also find that the high range of big ring gears and low range of small ring gears on the road bike means if I am in that middle zone which is a slight uphill, shifting the front derailleur means that I then have to make lots of shifts in the rear.
You raised lots of questions on what lasts longer and which is more efficient. Other than the article I cited above I have an observation from a tour I did a couple years ago. When I was touring in Florida which is flatter than a pancake, I think I was on the 16 and 18T sprockets 95 percent of the time. Around home where there are more hills, that probably drops to 80 percent of the time I am using those two sprockets. Thus, an eight speed cassette the way I use it might not last as long as a cassette with more sprockets because if I had more mid range sprockets in say a 15 to 19T range I would spread the wear across more sprockets. Bottom line, six of my sprockets will have a lot of lifespan left when I have to replace the cassette because two sprockets were badly worn.