I have always felt some drivetrain drag since switching to 1x on my MTB.
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I’d gladly take a few watts to not worry about dropping a chain with a 2x on my MTB. I did 1x on road for a while, but I’m back on 2x there.
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Ran 2x for a long time on the MTB, I can’t remember any dropped chain issues…but I was always anal about keeping it well adjusted and replacing everything when it started to show wear. I just put Eagle on my bike and man when I look down at the angle of the chain when I’m in the 50 tooth…its pretty extreme.
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It’s a shame they didn’t run the test with Sram Eagle. That’s what alot of mtb’s are shipping with these days.
Eagle XX1(1×12) vs XTR(2×11) is what I’d be really interested in.
I did some intervals on my Kickr a while back and compared variations between my PM data in various gears at 250w. Essentially, the results were pretty consistent in the highest and middle gear. The 50 tooth gave me back an extra 5 watts for some reason.
At the time I figured it was something to do with the Kickr turning at a lower speed. After reading this article I’m thinking it might’ve had more to do with pairing of 34/50 teeth.
I can’t say I’ll be rushing back to my Shimano 2x11 anytime soon. It’s much nicer when you can simply focus on riding, instead of trying to remember gear combinations.
Brakes, dropper, lock out and one gear selector is easy to do on auto pilot. I still get those wrong sometimes. 
Thanks for sharing.
My SRAM eagle 1x drivetrain is for sure higher friction vs my 2x road bike.
One very noticeable difference is much higher chain tension in the 1x.
I’ve never had a dropped chain on my MTB, however. And I’ll take extra chain tension for that.
I stuck with 2x forever but I’m so impressed with the 1x Eagle I cant imagine ever changing back even at the cost of a few watts.
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Practically speaking, there is also the issue of dropper posts and lockout levers.
A 2x with a dropper and a lockout lever is a very crowed cockpit.
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Intuitively, once you know that the largest factor in friction variation is chainline, it stands to reason that more chainrings in the front can reduce the average lateral distance between the active chainring and cog - assuming you avoid the extremes (which you can’t do on a 1x). And lower lateral distance means less lateral load on the chain, which means less friction.
Boy, I’d love to spend some time with that test equipment… Nice toys.
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I wonder once everything starts going electronic (AXS), if MTB’ers will have more options without adding clutter.
Although I’ve had a 1x11 on my Fat bike since 2013, my XC bike was 2x10. Just went to Eagle and the the first thing I noticed was the decrease in cognitive load when I took it racing. I liked the 1x12 performance when out riding with it before but did not expect the lagniappe on race day.
Been there. The local mtb club even created a meme about mine. The other downside was that I had top mounted dropper lever so I sometimes grabbed brake while trying to push the lever. 1x12 and a below mount dropper and no remote fork lockout is so much better.
I had to look that one over, I thought it was a typo. Learn new stuff every day!
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“Courteau” fits right in Louisiana. 
In the very very very northern part of it, yeah.
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It really is. I have 1x11 and when I was adjusting the derailleur after installing all the parts, there is a noticeable clanking sound when in the 32x42. The bend in the chain is quite visible.
