Comparing 1x vs. 2x by the numbers.

[Retrorockit]

Having modded my old 3x8 XC bike to 1x11 using a Zee M640 derailleur intended for 2x10s DH bikes. I wondered what if anything I was missing out on.
I ran both setups at Sheldon Brown's Bicycle Gear Calculator.
https://www.sheldonbrown.com/gear-calc.html
42x11-42t 11s top gear = 26.5mph @ 90rpm, and 6.9mph @ 90rpm in the lowest gear.
using 42t,32t 2x, and 11-32t 10s cassette top and low gears were the same.
So the capacity of the derailleur seems to be equal at both ends. Both cassettes used the same top gears, so no advantage in this case for closer ratios at higher speeds.
But I did test a much tighter 11-28 cassette with wider spread chainrings rings in the front. This provided much closer gears at the top end, and also closer gears at the bottom too. 2x gives more clearance for bigger front ring to the frame.
So road bike type gearing at the top is possible with that type cassette
My Front Freewheel Mod made 1x the best option for me due to chain management concerns favoring a Narrow/Wide chain ring and SS cage derailleur. My relaxed pace and flat terrain favor 1x also.
So I would say 2x is still valid if you go narrow on the cassette and wide on the chainring sizes.

 

[Frankenorange]

Just when you think it can't be possible to have another 1x 2x thread on the internet, it happens.

 

[Uncle Grumpy]

I wondered what if anything I was missing out on.

Probably something a lot of people wonder about, to be honest.

So I would say 2x is still valid if you go narrow on the cassette and wide on the chainring sizes.

I noted the industry went from:
3x9
2x10
1x11
The industry seemed to lose a chainring and add a rear sprocket. As such, I really thought 0x12 would have been the next logical step.

Anyway, over the years I have run the following gearing on MTBs...

3x7, 3x8, 3x9, 2x10, 2x9, 2x10, 1x10, 1x11, 1x12 and 1x1.

In my MTB fleet I still have 3x7, 3x8, 3x9, 1x10, 1x11, 1x12 and 1x1.

My conclusions, after extensive testing of various drivetrain combinations over the years, are as follows:

1. I like riding bikes.
2. Don't overthink it.
3. See No.1.