My impetus for testing the Carbon-Ti X-Lock thru axles was two-fold. First, I destroyed the Maxle on my Niner, so I needed a replacement. Second, if I can shed grams with no (or negligible) loss of performance, then I’m game. After consulting with the folks at Fair Wheel Bikes, who sell several brands of lightweight tooled thru axle and skewers, Carbon-Ti was the choice. They sent the rear 142x12mm X-Lock, and Carbon-Ti provided the RS 110x15mm thru axle to fit the Rockshox RS-1 suspension fork up front.

Gram for gram, after rotating mass, reducing unsprung weight can make the most noticeable difference in a bike’s performance. As Galileo and Newton observed, an object at rest wants to stay that way, and the heavier the object, the higher the force required to move it. So, reducing the weight of anything on the lower side of your suspension will speed up its reaction time and let the springs better do their job.

So, if you’re gonna replace a thru axle, might as well use that opportunity to cut the parts’ weight almost in half…


Carbon-Ti X-Lock lightweight alloy thru axle replacing broken maxle

Rockshox’s Maxle is spec’d on a huge variety of bikes. I have several of them in my own stable, and we’ve tested a great many more with that part. In most cases, they work fine. But on my Niner RIP9, there was something askew. I could have been the wheels, or a slight frame misalignment. Most likely, it was some combination of the two, but it was just enough to cause a very, very difficult insertion. That should have been enough of a warning sign, but I ignored it, hammered the axle into place and muscled the lever around and around until it was close enough to clamp it. That was fine, until it was time to remove it. And this this happened:

Carbon-Ti X-Lock lightweight alloy thru axle replacing broken maxle

Carbon-Ti X-Lock lightweight alloy thru axle replacing broken maxle

Assuming this ever happens to you, you’ll obviously need a replacement. Or, assuming you’re considering your options for making your bike lighter, the Carbon-Ti X-Lock alloy thru axles make a decent argument in the grams-saved-versus-dollars-spent conversation.

Carbon-Ti X-Lock lightweight alloy thru axle review and actual weights

The X-Lock axles are made for Rockshox and Fox forks (Boost, RS-1 and Regular) and rear axles to fit Syntace X-12, Scott, E-Thru and Maxle replacements, plus Maxle Boost and 150mm. They come in red, black, gold, blue, silver and two shades of green. Retail averages €76-85 / $70-85.

Carbon-Ti X-Lock lightweight alloy thru axle review and actual weights

Compared to the Maxle, the Carbon-Ti X-Lock saves 39g for an RS-1…

Carbon-Ti X-Lock lightweight alloy thru axle review and actual weights

…and 40g for a rear 142×12 Maxle. That’s less than half the weight, for a savings of 79g (0.174lb) on the bike.

Carbon-Ti X-Lock lightweight alloy thru axle review and actual weights

But the weight savings are only part of the benefit. The tooled design is also much narrower and sleeker, giving your bike a cleaner appearance and reducing the likelihood of anything snagging the dropout (or the dropout snagging a rock). The downside is you may need to pull out your mini-tool to fix a flat, which will add a couple minutes to the process.

Carbon-Ti X-Lock lightweight alloy thru axle review and actual weights

I was concerned that a lightweight axle might have an outsized impact on a fork like the RS-1, which relies heavily on overall axle system stiffness to help keep the bottom of the fork in line. After all, the lowers spin freely and independently of each other, which is why Rockshox introduced their Torque Tube oversized axle/hubs and Torque Cap oversized endcaps. Fortunately, the Carbon-Ti axles worked fine, maintaining the RS-1’s overall stiffness. I couldn’t tell any difference between the stock Maxle and the X-Lock.

Carbon-Ti X-Lock lightweight alloy thru axle review and actual weights

Out back, particularly on the Niner’s unified rear triangle, I didn’t have any concern about loss of stiffness.

Carbon-Ti X-Lock lightweight alloy thru axle review and actual weights

But the smooth appearance was much appreciated. I ended up putting them on both ends of my Niner JET9 RDO and on the rear of the RIP9. For a weight savings of more than half, there are certainly more expensive ways of dropping weight. Considering there’s no loss of stiffness and a potential improvement in suspension performance, the X-Lock thru-axles are a win in my book.

Available from Fair Wheel Bikes in the USA, or direct from Carbon-Ti in Europe.

UPDATE: Rockshox’s product manager chimed in to say they’ve tested a Maxle Stealth with the RS-1 and found that it started backing out and could come loose during a ride, which is why they haven’t made one for this fork. They have not tested the Carbon-Ti model, and I have not had any issues yet, but perhaps worth checking it before riding should you upgrade.


  1. RockShox doesn’t even recommend their own tooled Maxle stealth thru-axles for the RS-1 (as you mentioned, not enough clamping force). I sure wouldn’t want to use an aftermarket option.

    Probably a fine option for all other (99.999%) of thru axle applications though.

    • The author never said these reduced rotating weight. He said “Gram for gram, AFTER rotating mass, reducing unsprung weight can make the most noticeable difference in a bike’s performance.” So, according to Tyler, unsprung weight, which is what this replacement axle is, comes second after rotating mass.

        • I read it again, but don’t see any mention of axles rotating. Can you point out a specific passage where he claims axles rotate? All I say is talk of “unsprung weight”, and not rotating weight.

        • I’m the first to criticize BR for technical sloppiness like J describes, but like Tim, I just don’t see it here. Tyler, the author, points out that the sliders will rotate freely in the uppers with no hub in place. That’s absolutely true for most inverted forks, including Tyler’s RS-1.

          Is it possible that J doesn’t realize that this is an inverted fork and therefore misunderstood Tyler’s comment about how “the lowers spin freely and independently of each other?”

          If you want to criticize technical competence vis-a-vis this article, how about the fact that Tyler hammered in a through-axle that clearly wasn’t fitting? I think he may have literally hammered it (maybe with a mallet?). He managed to strip a bunch of anodizing off the axle, and the fact that he exerted enough force to do so mechanically means something was very, very wrong.

          Oh, and he crushed the QR end of the through axle.

          The fact that the Carbon-Ti replacement went in smoothly implies that the wheel was somehow misaligned with one or both dropouts, and rather than check the alignment and fix the problem, Tyler just applied a hammer to the problem.

          I spent a decade and a half, off-and-on, turning wrenches in a shop (I’m now a mechanical engineer). If a customer came in with a broken through axle and told this story, the mechanics would have waited until he was out of earshot and had a nice, long laugh at his hamfistedness. And then his story would have become the sort of shop lore you hear after closing when the beers get cracked open. It’s not honorable to laugh at customers like this behind their backs, but it totally happens.

          But Tyler doesn’t claim to be either a mechanic or an engineer. He claims to be a journalist. Journalists need to get the facts of the story right. As far as I can tell, he got the facts of this story right. He’s on solid ground as far as I can tell.

          • JasonK – Thanks (I think) for the response. No, thru axles don’t spin. Regarding the damaged Maxle, I believe it may have also (or primarily, even) been that the hub’s axle bore was out of spec and too narrow, or (more likely) the surface treatment was just ever so slightly too thick, which made it very difficult but not impossible to get the Maxle all the way in.

            But it would go in, and I needed to use that particular set of wheels at the time, so I provided a little incentive for it to reach the threads, at which point I could muscle it around until tight. No, I don’t recommend anyone else do this, but given the choice between riding or not, I suspect some riders would do the same thing. The outer face was damaged during removal because it was so tight that turning it via the lever required more force than the metal could stand, so it started breaking. That, in turn, made it even more difficult to remove, hence all the scratching and complete carnage.

            Yes, I’m sure the shop guys and girls would get a real kick out of this, but sometimes the end result can’t be predicted so we move forward.

  2. “So, reducing the weight of anything on the lower side of your suspension will increase its reaction time.”

    No. Reducing the weight will DECREASE reaction time, i.e. make it respond more quickly.

  3. Tooled axles are generally preferable to lever operated as they’re much less likely to get loose on their own, lighter and minimize chance of catching stuff on the trail.
    You’re carrying tool anyway, so no point in carrying 3 versions of it.

  4. So it weighs the same as the SRAM stealth options, costs twice as much. May be a win in your book, can’t say the same for mine…

  5. I can say that I had used the Fox Kabolt on my Float 34 Fork and was using a torque wrench to tighten it down properly and after about 2 months of constant wheel removals to transport my bike, it finally broke the tabs on my fork lowers that the little adjustment dial sit in. Just saying that with a QR15 axle you aren’t putting stress on those tabs because you get the clamping power from lever and not screwing in the axle to torque. Have you ever had any problems like this?

  6. I much prefer tool required axles. My x fusion metric axle is 110x20mm and is lighter than any tool free 100×15 axle. Or should I say 110×15 boost since that’s the new standard. So I guess if 110×15 is boost, 110×20 is boost+?

  7. Close to a 1/4 lb weight saving is pretty significant in my book. And it’s unsprung weight. I was really interested if the light weight would compromise rigidity but it doesn’t appear so. Any possible way to get an engineering company to test the strength of at least the rear axles (OEM vs Carbon-Ti, torsional load)?

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