Review: SRAM Force CX1 drivetrain with HydroR disc brakes

For pure cyclocross racing, you'd be hard pressed to find a better set-up

Cross Disc Parts
Up And Away

The weight penalty of disc brakes is lessened by the single chainring set-up with no front derailleur.

Editor’s Note: This article is part of our Cyclocross Race Bike Shootout series, which also includes reviews of top competition steeds from Trek, Jamis, Specialized, and Van Dessel, as well as tests of several wheelsets and ’cross tires.

The Lowdown: SRAM Force CX1 drivetrain with HydroR disc brakes

I was skeptical at the outset of my test time aboard SRAM’s Force CX1 single-ring drivetrain paired with the company’s hydraulic road disc brakeset, wondering if a 1x set-up would provide a wide enough gear range for cyclocross racing, and questioning how well SRAM could overcome the problems that befell its first iteration hydraulic brakes, which were recalled due to cold weather failure issues. But those worries have been eased. While not perfect, both drivetrain and brakes have proven to deliver reliable race day performance. Indeed, SRAM’s CX1 drivetrain paired with HydroR disc brakes would be my top choice for competitive ’cross racing — and could well be capably used for other applications such as gravel grinders, triathlon and even some criteriums. Check out the full review below to learn more about this dynamic modular system that’s convinced me to drop the front derailleur for good. And read about what improvements SRAM may have in store for both the drivetrain and brakes on page 2.

Thick Thin

The X-SYNC chainring teeth are designed to keep the chain securely in place — and shed mud better.

Stat Box: SRAM Force CX1 Drivetrain
Cassette: SRAM 11-32 or 11-36 Chainring: X-SYNC 38, 40, 42, 44, or 46t
Chain: SRAM PC-1170 Cranks: SRAM Force CX1
Levers: SRAM Force CX1 hydraulic Weight: 1150-1348 grams
Rear derailleur: SRAM Force CX1 MSRP: $874-$942
Front derailleur: Not applicable Rating: 4.5 Stars 4.5 out of 5 stars

Pluses
Minuses
  • Lower overall system weight
  • Bigger gear jumps
  • Improved chain security
  • Heavy rear derailleur
  • 1:1 shift actuation
  • Exposed shifter internals
  • Easy upgrade
  • B-limit screw adjustment finicky
  • Clutch derailleur ideal for cyclocross
  • Soft chainring bolts
  • Roller bearing clutch controls chain tension
  • Taller gearing compared to 2x systemss
  • Cage lock for faster wheel changes
  • Reduced maintenance
  • Improved hood ergonomics
  • Individual reach adjust
  • Reduced chain slap
  • Simpler operation
  • Exceptional mud clearing
  • Durability

Stopping Power

We like the extra power and modulation provided by the 160mm rotors. Now if we can just get Zipp to make us a set of tubeless ready thru-axle equipped wheels.

Stat Box: SRAM Force HydroR Disc Brakes
Levers: SRAM Force CX1 hydraulic Weight: 902g (levers, calipers, hose, rotors)
Calipers: SRAM Force CX1 hydraulic MSRP: $851 (rotors not included)
Pistons: 18mm front/ 18mm rear Rating: 4 Stars 4 out of 5 stars
Rotor: SRAM Centerline 160mm

Pluses
Minuses
  • Vastly improved braking compared to cantis
  • Weight
  • Allows for wider tire clearance
  • Boxy hood shape
  • Improved hood ergonomics
  • Brake bleeding complexity compared to cantis
  • Lower hand force required
  • Price compared to cantis set-ups
  • Individual reach adjust
  • Alloy caliper with stainless steel backed pads and stainless hardware
  • Fully sealed system
  • Tall hoods easier to grip
  • Easy to install and bleed

Full Review: SRAM Force CX1 drivetrain with HydroR disc brakes

Like a lot of people, I was skeptical at the outset of my test time aboard SRAM’s Force CX1 single-ring drivetrain paired with the company’s hydraulic road disc brakeset. As a mid-pack cat. 3 racer with a fairly low genetic-ability ceiling, I wondered if a 1x set-up would provide a wide enough gear range. As a follower of the cycling gear industry, I questioned how well SRAM could overcome the problems that befell its first iteration hydraulic road brakes, which were recalled at the beginning of last year.

Test Rig

We draped our SRAM CX1 and HydroR parts on the highly capable Van Dessel Full Tilt Boogie carbon cyclocross frame.

Flash forward about four months, and those worries have been eased. While certainly not perfect (what is?), both the drivetrain and brakes have proven to deliver the kind of reliability and performance that heretofore had been the hallmark of SRAM’s primary competitor in this space. For pure road applications, I’d still choose Shimano over SRAM when it comes to shifting and braking. I just think it works better. But for cyclocross racing, I’d flip that statement around. SRAM Force CX1 with HydroR disc brakes, in my opinion, is the top choice. And that statement holds whether you’re name is Jeremy Powers or Joe Schmo.

Clutch Addition

The SRAM Force CX1 roller bearing clutch helps maintain critical chain tension.

Security is Job No. 1

If you’ve raced more than a handful of ’cross races you’ve invariably encountered the dreaded dropped chain. It usually happens at the beginning of a race, putting you so far off the back you feel like dropping out. Or chain leaves chainring teeth sometime early in the last lap when a sure-thing top 5 turns into, I think I made the front half. Whatever the case, it sucks.

In the past, whether you were running a traditional 2x set-up or an old school 1x, your best defense against this malady was all manner of chain catchers, guides and watchers. Some worked better than others. None was a perfect solution. Enter the star of the SRAM Force CX1 show, the X-SYNC chainring. Utilizing the same thick-thin tooth pattern that’s all but killed the front derailleur in the mountain bike world, SRAM has created a secure chain-chainring interface that’s essentially eliminated dropped chains or the need to baby sit said chain with the aforementioned add-ons. The shape of the teeth help reduce side to side motion of the chain.

Working in concert with the X-SYNC chainring is SRAM’s Force CX1 rear derailleur with its roller bearing clutch. I wont delve too deep into the technical minutiae, but it’s basically the same rear mech used in SRAM’s wildly popular XX1 and X01 single-ring mountain bike drivetrains. Chain tension changes based on current gear selection, as the clutch takes up or lets out chain slack, keeping tension constant.

To you and I that means chain security — and peace and quiet. Gone is the whack-whack chain slap so common when rambling over bumpy terrain during a ’cross race. It’s a profound and welcome silence. So is not dropping your chain, which has happened exactly zero times during our SRAM Force CX1 test session, which included numerous races, hard-charging test rides, and some of the world’s sloppiest dismounts and remounts, when our bike was bouncing around like a kid in a jumpy castle. Still no chain drops.

All You Need

For us, the 11-32 cassette combined with a 40-tooth chainring was the ideal ‘cross race day set-up.

Right Gear for the Job

But all this chain security is meaningless if your gearing is so tall you have to dismount and run every time the course tilts slightly upward. That was certainly my biggest concern. I’ve never been a big power guy, and figured a 1x set-up would leave me turning squares — or just running a lot.

Not so. Just like with its XX1 MTB platform, SRAM has engineered enough gear spread into the CX1 system that just about any amateur level racer can set it up with enough variance to assure that pedaling — not plodding — is primary mode of race transportation.

Up front, CX1 users can choose chainrings with 38, 40, 42, 44 and 46 teeth respectively. The more teeth the taller the gear. I started out on a 42t, but quickly slotted back to a 40t so I could spin easier. Whatever chainring you choose, it’s paired with SRAM’s 11-speed cassette, which initially was limited to an 11-32. That combination of the 40/32 was plenty for just about any obstacle faced on the ’cross course, and I’d advise any amateur starting out on a 1x system to begin there and adjust accordingly. If you’re a spinner, fall back to the 38t. If you like grinding, the 42t chainring might be the way to go.

If you’re reigning national champion Jeremy Powers, the 44t is the choice. “I ran a 42 once this year because I was feeling sick and got out-sprinted at the finish because I didn’t have enough gear,” Powers told RoadBikeReview. Most people don’t have to worry about such things.

It’s also worth noting that in December, SRAM added an 11-36 cassette to its CX1 product mix. This is more gear than most people will need for cyclocross racing, but it opens up other interesting possibilities which are addressed on page 2 of this review.

Powerful Endorsement

Reigning U.S. national cyclocross champion Jeremy Powers is a vocal advocate for SRAM’s 1x drivetrain.

Weights and Measures

Depending on how you add SRAM Force CX1 to your life, the system will either increase or decrease the weight of your bike. And this speaks to another of the group’s upsides: modularity.

You can opt to swap on a full CX1 group plus hydraulic disc brakes, which will obviously be heavier than a traditional cantilever brake set-up. (Powers says his canti race bikes are about a half pound lighter than his disc steeds.)

You can also just add the X-SYNC chainring and CX1 rear derailleur to an existing 10 or 11-speed SRAM drivetrain, which would likely shed weight because you’re eliminating the front derailleur and a second chainring. The X-SYNC chainrings even come with the spacers to compensate for your missing old inner ring. Or you could try something in between, say adding a set of Red HydroR levers instead of Force, and Red crankarms (both of which would be lighter, but more expensive).

Whatever the case, all the X-SYNC chainrings are 110 bcd, which allows for all this swapping as long as your starting point is an existing SRAM 10- or 11-speed drivetrain. And if you’re going from a 2x to CX1, you can even strip out the internals of the left-hand shifter, since it will no longer have anything to shift.

Big and Beautiful

Though a little on the heavy side and finicky to set up, the SRAM Force CX1 rear derailleur does a solid job of moving the chain up and down the wider cassette and maintaining chain tension.

What’s Not to Like

Arguably the No. 1 thing you need to know is that by forgoing a second chainring and using a cassette with a wider gear spread, you’ll encounter bigger jumps between some gears. This wasn’t a huge issue during our test time, but there were certainly a few instances when the proverbial porridge was too hot or too cold but never just right. Whether it was grinding up a hill or trying to close a gap during a flat section, it sometimes felt like the gear I was in was too hard or too easy and the next one up or down was just the opposite.

But that’s the nature of the game when for instance you switch from the more tightly spaced 11-28 cassette (which has cogs of 11, 12, 13, 14, 15, 16, 17, 19, 22, 25 and 28 teeth) to an 11-32 (which goes 11, 12, 13, 14, 15, 17, 19, 22, 25, 28 and 32). Depending on what you were used to before, sometimes you’ll miss that 16 or 21 or 23, and there’s nothing you can do about. The good news is that if you’re like me, you’ll soon forget about what you’ve given up and get used to spinning a slightly different cadence.

Another rub on SRAM CX1 is rear derailleur adjustment. It can be a little finicky, and as one pro level mechanic put it, “There always seemed to be a compromise between great shifting on the top of the cog and great shifting on the bottom, but never perfect in both.”

This is tied to adjustment of the B Limit screw. SRAM recommends 1cm of clearance from the top of the pulley to the largest cog, but with an 11-32 cassette, that can cause the shifting in the lower cogs to be a little sluggish. It’s not like it doesn’t work, but in my experience it certainly could be a little more crisp. Edwin Bull, owner/operator of Van Dessel Bikes, which provided the full carbon Full Title Boogie cyclocross frame for this test, says he too is a big fan of SRAM Force CX1, but agreed that it can be a “little loud in the larger cogs.”

We broached this subject with Nate Newton, SRAM’s road technical marketing rep, and he admitted that overall he’ll spend more time adjusting the rear mech of a CX1 system versus a 2x rear derailleur.

“What I’ve found works best is to start by making sure the derailleur hanger is dead on,” Newton explained. “Then I dial out the B limit screw reasonably far because the system usually runs well with a big B gap. So I dial it out far enough that when I am going onto bigger cogs I am not going to have clearance issues with the top pulley going into those cogs. Then once I am on largest cog I dial the B gap back in until I am really getting a smooth shift off that largest cog.”

Newton adds that it’s also key to have set up the high limit correctly at the other end in the 11-tooth cog. “If that limit is set properly I can run reasonably low tension,” he continued. “This is something that applies to just about all SRAM derailleurs. If you get the high limit set right you can run much lower cable tension than you can with competitor’s groups. I think sometimes that’s something people forget. So dial in the B gap so the shift off the 32 is good and that tends to clear it up all the way through the cassette range.”

ATV

Our cyclocross bike has turned into our go just about anywhere bike.

Our pro mechanic also took issue with the openness of the HydroR shifter internals. “After any really dirty or dusty race, we’d have to flush out the shifter with WD-40 to get them to work correctly. They jammed up pretty easily.”

SRAM’s Newton said he wasn’t aware of this issue, adding, “We feel like our shifters with the way the rubber hood covers them, are more closed than our competitor’s product. But super muddy cyclocross is super muddy cyclocross.”

Fair point — and in our experience, which was limited to a very dry amateur ’cross racing season in Colorado, shifting performance held up admirably without much TLC beyond the occasional garden hose spray down. But if your ’cross arena is frequently drenched in muck and mud, it’s something to think about.

Continue to Page 2 to read about our test impressions of SRAM’s hydraulic disc road brakes and hear what SRAM may be planning for the future »
About the author: Jason Sumner

An avid cyclist, Jason Sumner has been writing about two-wheeled pursuits of all kinds since 1999. He’s covered the Tour de France, the Olympic Games, and dozens of other international cycling events. He also likes to throw himself into the fray, penning first-person accounts of cycling adventures all over the globe. Sumner, who joined the RoadBikeReview.com / Mtbr.com staff in 2013, has also done extensive gear testing and is the author of the cycling guide book "75 Classic Rides: Colorado." When not writing or riding, the native Coloradoan can be found enjoying time with his wife Lisa and daughter Cora.


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