I’m not a fan of 1-by drivetrains for mountain bikes (1-by, also called 1x, use a drivetrain with a single chainring matched to a multiple-cog cassette). I understand why the bike companies forced the technology on riders as the best thing since, well, the derailleur.
The 1x system eliminates the pesky performance and design issues of a front derailleur (always the drivetrain’s weak link) and the derailleur elimination increases the profit margin (do you remember getting a discount on 1x bikes because a $400 part was removed?). Another benefit (for bike companies, not riders) is simplified frame design and manufacturing. Punting the front derailleur allows designers to tighten up rear wheel tolerances and reduces manufacturing costs by skipping the derailleur mounting system completely. So 1x is a win for bike companies.
I never warmed to the system because I’m not a racer. I’m just a regular schmo who trail rides (like 99.3% of mountain bikers). I like the instant leg spin when the chain drops to the smaller chainring and the big torquey feel when pushing the chain to the big ring. These jumps allow a rider to attack an unexpected climb or increase speed on a descent without clicking a sifter 10 times.
VeloNews just published a great story by Lennard Zinn comparing the friction difference between a 1x and 2x drivetrain. It is not the same reason I dislike the 1x system but it gives my argument new ammunition. Plus, it might even change the mind of the .007% (racer types) who believed the 1x system was more efficient.
I’m going to nurse my 2x drivetrain as long as I can and resist the 1x movement. Heck, I still miss the 3x drivetrain except for how often they dropped the chain.