Cranksets from FSA, Truvativ and Race Face
By James Sharp

Cranks take a beating. Think about it, they are subject to the forces involved in pedaling, cornering, landing, bouncing through rock gardens, and running into stuff—often rock-stuff. Throughout all of this, we expect them to keep coming back for more. We expect them to not break. We expect them to not creak. We expect the bearing in the bottom bracket to not wear out. Pretty high demands, no? As far back as 1993, when the mountain bike boom was beginning to hit big time, Alex Pong and his company Magic Motorcycles took a clean slate approach to the crank/bottom bracket problem and came up with one of the most amazing pieces of workmanship ever to grace a mountain bike. They were light, and they were strong. They had the bearing located outside the bottom bracket shell so that they could utilize larger diameter ball bearings. They were almost $700. A few sets still float around, Cannondale bought Magic Motorcycles, but the idea was ahead of its time. Bullseye took another approach. Known for their hubs and BMX components, they made a two-piece crank, as apposed to the three-piece type that ruled, and still rules, the roost. The bottom bracket spindle was permanently attached to the drive side crank arm. The non-drive side arm attached to the splined spindle via pinch bolts. The cranks were Cro-Moly and while the design was stiff, it wasn’t that light and that, coupled with some tolerance issues, kept them from taking off. Why do I dredge up some long gone cranks from little known companies? The technology that they pioneered so many years ago is now charging full steam at the mountain bike market today.

Two piece cranks were brought back by Shimano in 2002 with the introduction of a new Dura-Ace group. 2003 saw XTR get the technology, dubbed HollowTech II, and last year the venerable XT crankset got the same treatment. This year, it trickled all the way to the LX group. Other manufacturers—Truvativ, Race Face and FSA, among others—were using ISIS splined bottom brackets at the time. The ISIS spline was in response to Shimano’s own proprietary splined bottom bracket. Moving to the ISIS splined interface was supposed to ease installation and improved the rigidity of the crank arm/bottom bracket interface and create a, generally, more reliable solution to the square taper that has been the norm for many decades. They used larger diameter spindles to create a stiffer pedaling platform but had to sacrifice the size of the bearings. This lead to premature wear and a fairly short lifespan in some of the ISIS bottom brackets. Fast forward to the 2004 InterBike trade show and every major crank manufacturer had a two-piece crank with bearings housed outside the bottom bracket shell.

The reasons for this are three fold. First, it allows bigger bearings for improved life. Second, it places the bearings farther apart, making the whole bottom bracket/crank package stiffer. Third, it allowed the bottom bracket spindle to be a much bigger diameter tube. Add all three improvements together and you get a crankset that is leaps and bounds more rigid than the previous generations. There is another benefit to consumers. What is the one part that really wears out on a traditional bottom bracket? The bearings. When you buy a new bottom bracket, you get the bearings and the spindle along with every other part. All you needed was the bearings. With the new system—what Truvativ calls Giga X Drive, FSA calls MegaExo and Race Face calls X-Type—the only thing you replace are the bearings; much cheaper than the old way.

In order to get a feel for this new technology, we rounded up the best XC cranks on the market that Shimano doesn’t make and put them head to head. From Race Face we have the Deus XC, from Full Speed Ahead (FSA) we have the K-Force MegaExo and from Truvativ we have the Stylo Carbon. That’s one all metal, one full carbon and one carbon/metal mix, respectively.

Truvativ Stylo Carbon
Race Face Deus XC
FSA K-Force MegaExo
Conclusion

Truvativ Stylo Carbon
Truvativ’s Stylo Carbon is the top of their cross-country line. It’s the lightest one they make, and the most advanced. The arms are made of a forged aluminum spine that is then wrapped with carbon fiber which is then cured under pressure. This provides two main benefits. First, it locates the spindle and pedals accurately during the construction process. Second, carbon fiber, though very strong, tends to fail catastrophically. Having an aluminum backbone greatly reduces this possibility. The carbon fiber makes the arms very stiff. The chain rings are made of 7075 aluminum and the bolts are alloy. The crankset, with the bottom bracket—all weights will be with the bottom bracket in this review—weighs 848 grams. The cranks are available with 170 and 175mm (tested) arms.

Installation of the Stylo Carbon was a breeze. Unlike the other two cranks, and unlike Shimano’s Hollowtech II, the bottom bracket uses only two spacers, one on either side of the bottom bracket shell. These allow the bottom bracket to work with either a 68mm shell (both spacers) or a 73mm shell (no spacers). With the other brands, there is a third spacer that is not used when the bike calls for an E-type front derailleur. Truvativ’s instructions don’t mention the use of an E-type derailleur, so while you could leave out the drive side spacer with a 68mm shell, you would be out of luck on a 73mm bottom bracket shell. As I stated, however, installation was a piece of cake, install the bottom bracket bearings—you did buy that new wrench for this job didn’t you?— then slide the drive-side crank arm in place. Line up the non-drive arm on the bottom bracket spindle splines and tighten the bolt. Unlike square taper bottom brackets, grease everything. The bolts, the splines, the spindle—if it has threads, grease it. If it slides into, or clamps around metal, grease it. Once the non-drive crank arm bolt is tightened to 35-40 ft-lb off you go.

Right away you’ll notice that these are stiff cranks. Much of that stiffness, however, is due to the external bearings on the bottom bracket. In fact, because all of the cranks in this review have the same bottom bracket configuration, it was difficult to tell the stiffness apart. Truly you have to ride this style of crank back to back with a traditional set up. If you do, you’ll be amazed at the improvement.

We found the Truvativ rings to shift very well. Even shifting under load—not something that you should do, mind you—we didn’t experience any chainsuck or hang-ups. The alloy chainring bolts are 5mm on one side and 6mm on the other. This makes them very easy to tighten, no need for a funny slotted screwdriver to hold the backing nut in place. The spider is bolted on with Torx screws, but we never felt the need to touch them. The spider never creaked or showed any sign of loosening up. The Truvativ Stylo Carbon’s retail for $399

Truvativ
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Race Face Deus XC
The Deus XC was the best looking crank out of the box. The polished silver crank arms and polished and burnished chain rings were jewel-like. It was a shame to put them on a mountain bike and get them banged up, dusty and muddy. But, taking one for the team, we mounted them up and beat them up like the rest of this group.

The Deus XC is the successor to the venerable Turbine LP. At 815 grams it’s the lightest aluminum crankset Race Face has ever made—and the lightest crankset in this review! Just because it doesn’t feature carbon fiber doesn’t put it at a disadvantage in that department.

The Deus XC is made out of a proprietary aluminum that Race Face calls Optim-Al. The cranks are partially extruded and then CNC machined into their final form. The chain rings are pinned and ramped for crisp shifts. The crankset is available with 170, 175 (tested) and 180mm arms. The spider and drive-side crank arm is one piece. The chain ring spacers are integrated to the spider, allowing for shorter chain ring bolts—a small weight savings, but when you are splitting grams, every bit counts. Unlike the other cranks reviewed, and unlike Shimano’s cranks, the Deus XC attaches the bottom bracket spindle to the non-drive arm. This way if you manage—somehow—to damage the spindle, you will be replacing the less expensive arm as well.

The bottom bracket features 3 spacers - 1 non-drive side and 2 drive side. This allows for the use of an E-type front derailleur without a hitch. As with the other bottom brackets in this review, you’ll need a tool similar to the Park BBT-9 wrench. The bearings are similar to the others in this review, also.

Installing the Deus XC turned out to be a bit on the difficult side. First of all, the cranks are thicker than the others in this test and the Jekyll test bikes had to be spaced just right—with the included washers—in order for the crank arms to clear the non-drive swing arm. This wasn’t an issue on our hardtail test bike, though. Second, these were the hardest to get the arm seated on the bottom bracket spindle, even with sufficient grease—and more than sufficient grease. There were so difficult to tighten, that the 8mm hex bolt started to round out on us. I’d be leery of taking these on and off very often since I don’t think that the bolt could take it. Once installed, the cranks seemed to bind a bit and didn’t spin freely. We experienced the same thing with the FSA and both cranks needed time to break in.

The chain rings, as noted, are pinned and ramped and shift well. However these were the only cranks that we had a problem with chain suck. In fact, at one point it was so bad that we bent a tooth on the inner ring, with a new chain and new crankset to boot. Once that tooth was bent, chain suck was horrible, as I am sure you can imagine, until we discovered the tooth and bent it back. It bent surprisingly easy but once back in place hasn’t given us any grief. Other than the inner rings bent tooth and the installation headaches, the crankset did its job well, though the chain and teeth didn’t seem to mesh perfectly. Normally, we chalk this up to new rings and an old chain, but in this case we installed a new chain at the same time as the Deus XC install. The Deus XC survived numerous beating with minimal scratches and dings. At $319 they are the cheapest, by far, in this review. Hmmm... cheapest and lightest, maybe there’s room for aluminum after all.

Race Face
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FSA K-Force MegaExo
Like the other cranks in this review, the K-Force MegaExo is top-of-the-line. The workmanship is top-notch down to the littlest details. The liner that keeps water out of the inside of the bottom bracket is made of aluminum with O-rings to seal out water and grit. The arms are carbon fiber, with the drive side arm and spider being of the monocoque variety—no bolt on spiders here. The Cro-Moly spindle is bonded to the drive side arm. The rings are ramped and pinned and are made of 7075 aluminum—a standard grade for this application. They are held in place with alloy bolts, but unlike traditional bolts, these use a Torx driver, T-30 to be exact. FSA is kind enough to include the Torx wrench, but doesn’t include the wrench for the bottom bracket. (So far Shimano is the only one that does.)

Like the Race Face bottom bracket, FSA’s uses three spacers—one on the non-drive side and two on the drive side, making the K-Force MegaExo E-type derailleur friendly. All of the spacers are machined aluminum except for the crush washers that are used to make sure you tightened enough. We did experience a bit of drag when the cranks were first installed, but it went away during the first ride. The bottom bracket uses the same wrench that the other cranks do in this review, and the bearings are the same size, though they may not be completely interchangeable.

The FSA rings shifted very well. We never experienced any chain suck or grinding shifts. In fact, if anything the rings let go of the chain too easily, every time I would lay the bike down—whether crashing or otherwise—the chain would fall to the next smallest ring. I never lost the chain while riding though, so having it fall when the bike was tipped over was a trivial, but interesting, occurrence.

We were a bit concerned about the durability of the carbon arms since abrasion resistance isn’t what carbon fiber is known for, but my concerns were unfounded. We managed to bang the K-Force pretty good against some rather jagged rock and they came away with only surface damage. FSA puts a rather tough clear coat over the delicate fibers. Not only were the arms durable enough, they proved to be plenty stiff as well. Frankly, all three cranks were plenty stiff. So stiff, that discerning a difference among them wasn’t possible. We’d need some serious lab equipment to do it; our specially calibrated legs weren’t up to the task.

Really, the only area where the K-Force MegaExo cranks fail to shine is at the cash register. They are By far the most expensive cranks we have ever ridden. At $499, they cost more than the pricey XTRs. That is the price you have to pay to get the spider and drive side arm one piece. Granted, the level of craftsmanship is evident in every aspect of the crankset and bottom bracket. These cranks exude quality, and they should for that much money. You do feel like you are getting really high-end cranks and that goes a long way toward reducing buyers remorse. Though lightweight, at 850 grams, they aren’t the lightest.

Full Speed Ahead (FSA)
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Conclusion
Now comes the hard part. All three cranksets— Truvative Stylo Carbon, Race Face Deus XC and FSA K-Force MegaExo—are very, very good cranksets. They are all stiff, they all shift well and they all look great! Truly, you could almost just go with what material you liked best, or what your wallet could handle and you’d be fine. But my job is to pick a winner, and hard as that might be, I’ll do it!

Frankly, I feel that, for my money, I’d buy the Truvativ Stylo Carbon. Why? Well for a number of reasons. First of all, it was as easy to install as the FSA, and a lot easier than the Race Face. I am concerned about the fact that we were able to start rounding off the bolt, even using the correct size hex wrench that was in good condition. And we didn’t over tighten the bolt either.

Second, the shifting was as good as all the others and we didn’t experience any chain suck. Here again, the Deus XC lost a bit. I was very surprised by the ease that we bent a tooth on the small ring; the durability seems to be lacking.

Finally, the Stylo Carbon, while expensive, no doubt, is $100 less than the FSA. Really, they both are very, very good cranks, but I’d save the C-note and spend it on other components. The shifting is the same, the durability is the same, there was no noticeable difference in stiffness and the weights are within grams of each other. If you can’t afford either carbon crank, or you just want the lightest, then the Race Face is your only choice, but I’m not that much of a gram counter and would rather have easy installation and durable chain rings.

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James Sharp is a contributing editor for GearReview.com specializing in mountain biking. He has been known to pedal in squares, but tries not to.