Converting a 2×10 Drivetrain to 1×10

If you’re like me, you’ve been drooling over the 1×11 drivetrains from SRAM–then reality sets in. Sure, the gear itself is expensive, but honestly it’s also a lot of work to convert your existing drivetrain. Not only do you have to replace the chain, crank, cassette, shifter, and derailleur, most folks will also need a new rear wheel hub to mate with the cassette–which means either a new rear wheel or at least a full wheel rebuild. Whoa.

I’ve been riding 1×9 on my hardtail 29er for several years now, and I love it–so much so that this bike is generally my go-to ride. But that has meant my fancy carbon Santa Cruz Tallboy just sat in the shed for most rides. I had to see if swapping out the drivetrain would convince me to ride the Santa Cruz more often.

The SRAM X0 2×10 drivetrain is really slick and I’ve run it in a few different configurations, swapping the group between both of my bikes. I’ve run X0 2×10 with grip shifters and even mated it with a Race Face crank. I love the carbon cranks, the meticulous machining on all the parts, and the solid derailleur and shifter action.

The problem, in my view, is that a 2×10 drivetrain is missing the most-used chainring: the middle ring. Sure, most of the gear ratios are still there compared to 3-by setup, but the problem is you’re constantly shifting the front derailleur to progress through those gears, particularly in the middle of the range. I love my 1×9 drivetrain precisely because there is no front derailleur to fiddle with, and the 2×10 actually requires extra front derailleur shifting.

Ok, sure, having to shift a front derailleur is a first-world problem, but once you go 1-by, you never go back (or something like that). So I had to see if I could convert my SRAM X0 2×10 drivetrain to 1×10.

The Parts

SRAM lists a 1×10 conversion kit on their website, which made the project seem simple. The kit (listed at $72 MSRP) is said to include a 32t chainring and guard. There’s no photo on the website, and I assumed there was a 32t chainring that could be attached to the inner chainring bolt holes while the guard would attach to the outer bolt holes. But it didn’t matter how it worked–my LBS couldn’t track down the part. Even QBP had never heard of it. Vaporware?

My next thought was to simply track down the necessary parts (chainring and guard) individually. The LBS wasn’t able to find the parts immediately, so I took to the internet and read good things about the custom parts from Homebrewed Components. I could have a 32t chainring machined with the proper bolt spacing I needed plus it looked like I could find a guard pretty easily. But due to popular demand, Homebrewed isn’t promising anything delivered sooner than 12 weeks out.

The next day I got a call from Mark at the LBS, and he had found a solution! North Shore Billet produces a 1×10 direct mount chainring (about $65) that’s compatible with SRAM X0 and X9 chainrings with a removable spider. Within a few days, the part was in my hands, and I swapped out the 2×10 spider on my crank and slid the direct mount chainring on board.

Spider removed from the standard SRAM X0 crankset.

Word on the street is a direct mount chainring is more efficient at transferring power because there’s no flex at the spider–every bit of power goes straight into spinning the shaft. I’m not a sensitive enough rider to notice the difference, but I can say it feels super solid on the trail.

Now, chain retention is an issue with any 1-by drivetrain, as I found out with my 1×9, which would drop chains like a ghost in the attic. On my 1×9, I run the XCX chain retention system, and it does its job flawlessly with minimal added weight. This time around, I also considered a type-2 derailleur with a clutch like the derailleur used in SRAM’s 1×11 drivetrains. SRAM offers 10spd type-2 derailleurs, and the X9 version is priced fairly reasonably ($116 MSRP). But I was too anxious to start riding, so I would decide later.

On the Trail

I took the bike out on a shakedown to really see what it would take to drop the chain. Extended stair descents, bumpy gravel road burners, and even launching the bike in the air didn’t budge the chain. I suspect the ramping (or lack thereof) and the thicker teeth on the North Wave Billet chain ring really help here… or I’ve just been lucky so far.

I’ve been riding my Tallboy 1×10 for several weeks now, and the revamped drivetrain has made a huge difference. My rear cassette is 12-36 which doesn’t have quite the low end like my 1×9 drivetrain (11-32), but having that 36t cog is nice on super steep stuff.

After riding 1×9 for several years, I haven’t found 1-by gearing to be too limited, even in the mountains of Colorado. Dropping down to a single chainring up front isn’t for everyone, but for many riders it might just scratch an itch. And with a simple conversion like this, you can always go back if you don’t like it!

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