Hunting for the last spots to save weight? Try those heavy arse alloy thru axles that keep weighing you down. Holding you back. Keeping you from glory. German upstart Aserra has the answer with their carbon fiber and titanium thru axles starting at just 19 grams.

And these aren’t just lightweight parts without concern for safety. We spoke with them at length about the design, and they’re coming from a guy who makes custom titanium bolts for high end sports car owners seeking every last way to spend their money. Er, improve performance. The point being, he knows how to make parts that won’t break under pressure, and that track Porsche is going to stress a component more than you are. So, 19g thru axles…

aserra carbon fiber and titanium thru axles for road and mountain bikes are the worlds lightest bicycle thru axles

The 19g weight is for a 12×120 front thru axle. Don’t have a 12×120 bike? Yes, you probably do. They measure the actual length of the axle, and each one is custom made to fit the exact application it’s sold for. Which means when you install it, the threads will go all the way to the edge of your frame or fork, maximizing contact and support. Weights go up to 28g for the biggest 190mm rear axle.

does anyone make carbon fiber thru axles for road and mountain bikes

Those weights are particularly impressive considering the titanium he’s using is about 40% heavier than alloy would be. The Ti inserts run deep enough to handle the shear forces where it sits inside the dropout. They use automotive bonding agents with insertion ports to ensure adequate glue gets where it needs to go. Hex drilled tool ends offer the highest precision tool interface.

what are the lightest thru axles for a road bike and mountain bike

It’s a hollow carbon shaft, with sealed ends so they won’t fill with dirt. Available in many lengths, with all the popular thread pitches. And different finishes. Retail is €99.50 per wheel.

Aserra.de

16 COMMENTS

  1. >Those weights are particularly impressive considering the titanium he’s using is about 40% heavier than alloy would be
    What do you mean? All metals used in bike parts are alloys. This is u professional and propagates such usage further.

  2. Shouldn’t there not be significant shear forces on the axle?

    Which brings me to my second point. How does one ensure these stay tight. The benefit of a normal steel QR was that the 9mm rod would get stretched under tension and help hold the system and prevent loosening.
    Thru-axles largely stopped this as the Al tubes were too big to stretch (and Al is horrible for that).
    This is why a lot of screw-in TA’s (i.e. RWS) loosen over time and require periodic checks (my mtb rear without a quick release lever will go loose over time, whereas my front with tension lever doesn’t – assume all those linkages and cams act as a spring like the 9mm rod use to)

    Given CF tensile strength, how do these perform? I’d assume little to no stretch at normal tightening levels.
    Therefor, whenever there is some flex in the frame/hub, these can unload and go loose. And if they do get loose, should I worry about a crack at the insert-tube interface which will bite me later.

    • For standard quick releases, it was stretch (of a 5mm rod, not 9mm) plus the fact that the cam went over-center. While some thru axles incorporate a cam, some of those (lookin at you Formula) really suck. Sufficient torque should keep them from backing off, but torque specs very widely. I’ve seen 10Nm, I’ve seen 20. Larger axle faces could help too.

      • Although the cam went over center, the other end was threaded and technically free to back off. The over the center cam design just kept the cam from popping open.

        Bolt joint integrity is primarily accomplished by bolt stretch and elastic compression of the clamped surfaces. Higher torque helps accomplish that as you are imparting strain via increased bolt tension. Most bolted joints don’t need it but critical ones will specify a bolt free stretch length to ensure adequate spring effect, along with more precise tension methods than torquing.

        Larger axles faces may actually hurt torque retention if the interface flexes, which is likely given the lightweight nature of bikes. Although it could stiffen the interface enough, which is what TA’s are for after all. In the end, TA works, but they do seem to need more (very easy) maintenance. I don’t know of any improvements that are without at least some downside.

        • Anytime you thread aluminium into aluminium on a bike it has a habit of working loose. I fully expect the Ti threads here will be of big help. Just make sure you,ve got some anti-seize on there, you don’t want to break the thread off a three part axle, or strip out your frame or fork.

  3. The weight savings of these vs light aluminum ones from Extralite, Carbon-ti, or even Robert Axle Project, standard Specialized, Maxle Stealth, is little to none.

  4. The Maxle that came with my Reba fork weighs all of 35g. The list of things that I would spend 100 euro on before buying a lighter thru axle is virtually endless.

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