It’s been nearly 18 months since we first spotted SRAM’s one-by drivetrain. At that time it was a simple 1×10 design, its only distinguishing feature a redesigned, XX1-style chainring. Since then, we’ve watched what we now call CX1, formally unveiled this week, evolve on some of the fastest cyclocross racers’ bikes.
The SRAM CX1 drivetrain sports many of the same technologies as the wildly popular XX1 and XO1 mountain bike drivetrains. Current SRAM 11-speed road group owners can upgrade to a CX1 system for $366, assuming the rider is already using a compact, 110 BCD, cranks, by replacing only the rear derailleur and the chainring. The bigger the chainring, the more it costs, as the machining that goes into it is time consuming. The total cost of the CX1 group is set to be about $100 less expensive than a Force 22 drivetrain — not counting brakes on either group.
PHOTOS: The evolution of SRAM CX1
The new group should start showing up on complete bikes in May, and will be available in the aftermarket in June or July. By May, we would expect to see the CX1 drivetrain paired to hydraulic disc brakes and levers.
At the time of our test ride, SRAM employees said they wished they were launching the group with hydraulic brakes, but as we all know, the recall of the SRAM HydroR brakes in December made that impossible.
SRAM Force CX1 Rear Derailleur — $235
At the heart of the CX1 group is the X-Sync chainring and the Force CX1 rear derailleur. The Exact Actuation of the rear derailleur makes it cross compatible with 10- and 11-speed SRAM drivetrains, but not cross compatible with XX1 and XO1 rear derailleurs, as the mountain bike rear derailleurs require a different amount of cable pull.
The Force CX1 rear derailleur shares the X-Horizon, Roller Bearing Clutch, and Cage Lock technologies with the mountain bike rear derailleurs. The Force CX1 derailleur is available in a short-cage and mid-cage version. The long-cage version is compatible with the larger range cassettes.
The Force CX1 rear derailleur costs twice as much as the Force rear derailleur. It does sport more technology than you’ll find in another mechanical road rear derailleur, but the price still seems rather high.
SRAM X-Sync Chainrings — $126-$152
The X-Sync chainrings are compatible with all compact cranks. Just like the XX1 chainrings, the cyclocross chainrings use taller, squared off teeth, and a wide-narrow pattern, a technology SRAM calls X-Sync. The taller teeth engage the chain earlier and the wide-narrow patter is intended to mirror the chain.
The rings are available in five tooth sizes: 38, 40, 42, 44, and 46. CX1 cranks will be sold in GXP and BB30 cranks for $148 and $182, respectively. The CX1 cranks will be sold without any chainrings.
SRAM Force CX1 Left Brake Lever — $113
The SRAM Force CX1 left brake lever is quite simple. SRAM employees admit that the CX1 brake lever is simply a Force left brake/shift lever with all of the shifter internals removed — something that single-ring cyclocross racers and singlespeed riders have been doing for years to SRAM levers.
Chain and cassettes
The Force CX1 group calls for the rider to use the same 1170 Force-level cassette and chain. The 11-26, 11-28, and 11-32-tooth cassettes are all compatible. The long-cage rear derailleur is compatible with all three cassettes, while the mid-cage works with just the 11-26 option. Riders can easily swap between cassettes with different ranges, as the rear derailleur’s b-limit screw is adjusted in the 11 tooth cog.
The recommended chain for Force CX1 is the PC1170. The XX1 chain is also compatible and is a more durable chain, at a slightly higher price.
First ride reactions
We spent some time on a 42×11-28 setup back in February. The first thing we tried to do was bunny hop and run off as many curbs as possible, anything to try and pop the chain off the chainring. We were unsuccessful. Even when riding on a rough road, we couldn’t hear any chain slap. Bringing a roller clutch to cyclocross is a fantastic advancement.
The shifting is crisp. In our one ride, we noticed the shifting actuation to be as crisp if not more so than a Red 22 drivetrain. The rear derailleur’s roller clutch keeps everything quite tight, and it’s felt in the shift paddle.
The left lever has an unfinished feel to it, as there’s a large hole left behind the brake paddle, where the shifter internals used to be. SRAM product managers are aware of this shortfall, and hopefully it will be remedied down the road.
We found the gearing to be adequate for the roads were on, but cyclocross is a different story. The 42-tooth chainring is likely to be spec’d on most CX1 bikes this year, and we fear that many amateur riders will find themselves over-geared. At the 2014 USA Cyclocross National Championships, Ryan Trebon (Cannondale-Cyclocrossworld.com) rode a 44-tooth chainring. However, at the 2013 Clif Bar Cross Vegas, Ben Berden (Raleigh-Clement) rode a 42-tooth Shimano chainring paired to a 12-26 cassette, and if that chainring is good enough for Berden on the fastest course of the year, it may be a bit of a tall gear for the average rider. If we were ordering a group for our cyclocross bike, we would opt for a 40-tooth chainring paired to an 11-28 cassette.
We look forward to testing the Force CX1 group extensively in the coming months and hopefully a road version in the future.