We are now selling Wolf Tooth Components, a local outfit that produces a line of innovative, high-quality chainrings and cassette cogs. Wolf Tooth components are intended to convert 10sp drivetrains to elegant single-chainring configurations. You may be thinking that single-chainring drivetrains are nothing new, but Wolf Tooth has elevated this type of configuration to a new level. I'll get to the details below.
Here's my Moonlander with a Wolftooth drivetrain.
Notice the big black cog on the cassette. This is the 42t Wolf Tooth GC cog on an XT 10sp cassette. Installation requires removal of the 17t cog from a Shimano XT M771 11-36 cassette, and then install with the 42t cog in back.
With the 42t cog, this cassette now has a nearly 400% gear range.
The front end of the drivetrain includes one of the Wolf Tooth Drop Stop chainrings. The one I have is a direct mount on a SRAM/Truvativ X9 crank, but these rings are available in various bolt patterns too. The Drop Stop feature is an alternating thick-thin tooth profile that mates nicely to the alternating thick-thin gaps in the chain. This makes it difficult for the chain to fall off in the rough stuff.
By the way, this crank is not intended for the effective width (190 mm) of the rear hub on the Moonlander. By using Wolf Tooth's BB30 ring, the chainring is set further outboard for a better chainline and clearance for big tires. So I get good chainline and tire clearance with a slightly lower "Q-factor".
Plenty of chainstay clearance with the narrower crank!
A note on derailleurs: These Wolf Tooth cogs and rings are designed for Shimano and SRAM 10-speed mountain bike groups. The Drop Stop chainrings are intended for use with a derailleur that has a clutch mechanism to retard bouncy forward motion of the derailleur arm to prevent chain slap. Shimano calls this feature "Shadow +" and SRAM calls it "Type II". In our experience, the SRAM shifts much more smoothly than the Shimano with the modified 11-42 cassettes.