When SRAM released their CX1 components in 2014, the purpose-built group delighted gearing-nerds (including yours truly) who had previously cobbled together road and MTB parts to come up with road-worthy 1x drivetrains. The Chicago-based company followed up with the 1x™ Wonder (11-36) cassette, and in April of 2015, SRAM announced the Force 1 and Rival 1 component groups which offered even more gearing options.
Over the past nine months, I’ve logged nearly 2,000 miles on SRAM’s 1x (pronounced one-by) road components. Starting with the CX1 group in late 2014, I added the aforementioned 1x Wonder cassette to the mix, and then in May of 2015, I upgraded to the new Force 1 components. During this period, I tested four different X-SYNC™ chainrings (38t, 40t, 42t, 44t), three different cassettes (11-32t, 11-36t, 10-40t), and two X-Horizon™ rear derailleurs (medium- and long-cage). Braking duties were handled by Force hydraulic discs. Wheelsets tested included Rolf Prima’s VCX Disc and Zipp’s new 30 Course tubeless hoops.
Why would someone want only one chainring? According to SRAM, 1x road drivetrains are quieter, more secure, and offer a the rider a more simplified user experience. Getting rid of the front derailleur and second chainring also leaves more room for fat(ter) tires and fenders. An added benefit is that 1x drivetrains are easier to clean and maintain.
If you’ve spent any time riding a geared bike on dirt or gravel roads, you’re probably familiar with the sound of the bike’s chain slapping against the chainstay. It’s certainly annoying–and what’s worse–it can be the last sound you hear before the chain jams between the tire and chainstay. After riding thousands of offroad miles on bikes with 2x drivetrains I didn’t realize just how noisy they were until I started testing the SRAM 1x drivetrain. My Force 1-equipped Salsa Vaya was eerily quiet on the local trails. With chainslap all but eliminated, the only noise came from the bike’s tires crunching on loose dirt and gravel.
With conventional 2x drivetrains, the front derailleur does double-duty as a chain retention device. Even then, many riders rely on some type of chain catcher/keeper to prevent the chain from jumping off the small chainring. Having seen my share of dropped chains over the years, I was somewhat skeptical that SRAM’s X-SYNC chainring would be able to keep the chain securely in place. It turns out that my fears were completely unfounded. After logging nearly 2,000 miles on SRAM 1x, I’ve never a dropped a chain. It hasn’t been for lack of trying, either. I’ve bunnyhopped curbs, hit expansion joints at 30+ mph, and launched the bike off dirt kickers. Not once has the chain fallen off.
For most riders, shifting gears is a pretty simple process. Sure, things have become easier with the advent of integrated brake/shift levers, but the basic concept remains the same. One lever moves the rear derailleur, and the other lever controls the front derailleur. Rocket science it is not. Could removing one of the shift levers really change the user experience? It’s very subtle, but the answer is yes. The next gear–whether it’s higher or lower–is always just one shift away. You no longer have to worry about whether you should be in the large or small chainring because it’s simply not an option. If you do find yourself suddenly needing a much easier gear, you can shift up to three cogs in one sweep with the Rival 1 and Force 1 levers.
Will 1x drivetrains make 2x (and 3x) setups obsolete? The answer is, it depends. If your riding style or terrain demands a wide gearing range and small gaps between the gears, a 1x drivetrain may not be the best choice. While SRAM’s XG-1180 cassette offers eleven gears with a 420% spread, the gaps between gears are greater compared to a drivetrain with 50/34t chainrings and an 11-32t cassette. For commuting and non-technical off-road use, I found the combination of a 42t chainring and 10-42t cassette to be more than adequate (and quite enjoyable). That said, my 2x-equipped bike was usually a better choice for fast, hilly club rides where the smaller gaps between gears enabled finer adjustments to cadence (and speed).
Whether you’re converting an existing bike to 1x or building one up from scratch, be aware that SRAM’s XG cassettes (the ones with 10t cogs) require XD-compatible rear hubs or drivers. Most hub manufacturers offer XD drivers, but some wheels will require re-dishing after swapping freehubs. Also note that a standard 114-link chain may not be long enough for certain gearing combinations or frames with long chainstays. When testing an 11-32t cassette, 40t chainring, and medium-cage derailleur, a standard-length chain was all that was needed. Moving up to a 10-42t cassette, 42t chainring, and long-cage derailleur, however, necessitated adding a few extra lengths to the PC-1170 chain.
With the Interbike trade show right around the corner it will be interesting to see how many 2016 bikes are spec’d with SRAM’s Rival 1 and Force 1 components. Some manufacturers–including Marin–have announced models with 1x drivetrains, but will more follow? Stay tuned for GRAVELBIKE’s coverage of Interbike and reviews of more 1x-equipped bikes.
Disclosure: SRAM provided review samples for this article, but offered no other form of compensation in exchange for editorial coverage.