We've log a lot Gravel miles every year preparing for races and rides like Almanzo and Dirty Kansa, and we wanted share the tech and details of the 1x drivetrains we use. As with mountain biking, 1x allows you to eliminate the weight and clutter of the front derailleur and cable without giving up the gear range of a conventional double chainring drivetrain. After riding these 1x setups all for several years now, we are thrilled with the performance and will not be going back to a 2x drivetrain for gravel/CX bikes!
Below you will find some considerations on gear range, some help on chainring size selection, the best 1x Shimano setup, and the best 1x SRAM setup.
SRAM 10spd road shifters have the same cable actuation as SRAM 10spd mountain bike shifters so you can use a moutain bike rear derailleur with road shifters. The clutch on the rear derailleur will help prevent chain suck when the lube is worn off your chain and the also eliminate the annoying sound of the chain banging on the chainstay. A short cage derailleur works great with a typical 11-36T MTB cassette but a medium cage will be needed if you want the extra low range of a 40T or 42T GC. With respect to 11 speed, SRAM offers several 1x road/Gravel options that work great with our Drop-Stop® chainrings on your current crankset!
Now with our RoadLink you can use your 10 or 11 speed in a wide range cassette 1x application. The details of the Roadlink can be found here, and the basics are that this little engineering trick allows any Shimano road derailleur to work with up to an 11-40 cassette in a 1x applications! As with the SRAM, sometimes we run an 11-36t casette, but with hilly courses we pull out the 11-40. With 10 speed, this means having a standard 11-36 cassette and also our GC40 cassette and 16t cog available. With 11 speed, there are stock 11-36 (only SRAM, but works great) and 11-40 cassettes. Note that Shimano does not offer a Road/CX clutch solution, but for Gravel and All Road use the chain retention of our ring with the non-clutch derailleurs is excellent. If you want extra security, a simple small chainguide can be added.