Question: I currently have a Shimano XT 3x10 drivetrain. I’ve found I spend about 90 percent of my time in the middle ring. SRAM’s XX1 group is appealing, though I’d like to experiment with my existing drivetrain before replacing it. Any suggestions on how to proceed?
There is an undeniable appeal a to a single chain ring setup, provided it suits your riding style and terrain. Ditching one or more chain rings, a front derailleur, shifter, and the associated cable and housing not only sheds close to a pound, but also adds a bit of simplicity at a time when handlebars are increasingly cluttered with GPS gadgets, dropper post remotes and suspension lockout levers.
Here’s a brief overview of how to convert a double or triple chain ring setup into a reliable 1x drivetrain that, admittedly, lacks the range of SRAM’s XX1 group, but makes use of many of the components you already own.
Ditch the shifty bits
Remove your front shifter, front derailleur and all your geared chain rings. This includes your 32-tooth ring (if running a triple). While you can experiment with the 32-tooth ring you already have, it’s far from optimal for the intended application. Geared chain rings are designed with ramps, pins and tooth profiles that ease the chain’s transition from one ring to another—great for smooth and fast shifting, not so hot when you want the chain to stay put.
Acquire and install non-shifty bits
Chain retention is key to creating a reliable single-ring drivetrain, and your chain ring is your first line of defense again dropped chains.
A singlespeed-specific chainring lacks ramps and pins. Its teeth that are taller its geared counterparts, which aids in chain retention.
Tip: When installing your single chain ring, consider replacing the alloy chain ring bolts with steel ones. While heavier, they are stronger and better suited to the high loads placed on them.
There are a number of singlespeed-specific chainrings to choose from, and, thanks to the advent of SRAM’s XX1 group, several companies are now producing chain rings with alternating width tooth profiles, similar to SRAM’s X-SYNC technology. Matching the width of teeth to the inner width of the chain's plates greatly reduces side-to-side movement of the chain, thus reducing the likelihood of dropping it.
Wolf Tooth Components produces chain rings (shown) with alternating width tooth profiles in several common bolt circle diameters. e*thirteen was showing off similar prototype chain rings at this year’s Sea Otter Classic
While not a necessity, rings such as these can reduce the likelihood of dropping a chain. When used in conjunction with a rear derailleur with a clutch mechanism, such as Shimano’s Shadow Plus or SRAM’s Type 2, you may find you are able to successfully run your 1x drivetrain without a chain guide. For best results, consider running a medium cage rear derailleur as well.
A rear derailleur with a clutch mechanism, such as this Shimano XTR model, will keep your chain in check
Choose a chain guide
As mentioned above, some set ups may not require a guide at all. If you do find you need additional chain management, a simple upper guide should suffice for cross-country and trail riding. If you’re on a tight budget you can use your front derailleur as a chain guide by adjusting the limit screws to position it appropriately.
A guide such as this MRP 1x is generally sufficient for cross-country and trail riding
Resize your chain
Last and certainly not least: shorten your chain. Failing to remove links will result in excessive chain slap and poor shifting performance.
When sizing a chain, the general rule of thumb is “big-big plus two”, which is to say, size your chain by wrapping it around the largest chainring and largest cog on the cassette (without routing the chain through the rear derailleur), then add two links to get your ideal chain length.
The problem with this approach for single-ring drivetrains is that you will frequently find yourself pedaling in the “big-big” chain ring combination. This is to be avoided when running three chainrings, as it can stretch the derailleur to its maximum capacity. Try the following when sizing a chain for your 1x setup: wrap the chain around the chain ring and around the largest cog on the cassette (without routing the chain through the rear derailleur), but try adding four links, rather than two—you can always remove additional links if needed.
SRAM recommends sizing their XX1 drivetrain with four links of overlap, consider using this approach with your single-ring setup as well—you can always remove links if needed
Tip: If sizing a chain for a full suspension bike, consider sizing the chain with the suspension compressed to take into account rear axle movement, i.e., chain growth.
To sum it up:
Benefits of a single-ring drivetrain
- Less maintenance
- Less clutter
Recipe for a successful single-ring conversion
- Singlespeed-specific chain ring
- Steel chain ring bolts
- Medium cage rear derailleur with a clutch mechanism (Shimano Shadow Plus or SRAM Type 2)
- Appropriately sized chain
What do you think: Would a single-ring drivetrain be sufficient for where you ride?