Friday Group Ride #317

Friday Group Ride #317

Greg says “thraxle,” which sounds like some sort of insect anatomy term, but it’s (just barely) short for thru-axle. Never mind that a conventional 9mm skewer is also a thru-axle, the term refers to the new bolt-in 12mm and 15mm axles that have been standard on mountain bikes for several seasons now but may only recently be reaching critical mass on mixed-terrain and even road bikes. Watch new fork offerings to find out for sure whether we’ve reached tipping point, but I suspect we have.

Why is this happening? Well, as disc brakes proliferate, thraxles provide the advantage of greater lateral stability, i.e. less wheel flex, so that rotors remain centered in their calipers. Disc wheels set up with the older QR system do seem to have more brake rub than wheels with the new axles. If discs are the first domino, then thru-axles are the second.

All of this is converging on mixed-terrain and road bikes now, because riders have come to see how much more confidently they can descend big mountains with disc brakes. The idea that discs are the ideal braking system for carbon rims is a bit of a red herring, I think, since carbon rims haven’t entirely trickled down to the average roadie yet. But even on alloy rims, the advantage on those big drops has convinced more and more riders to go disc.

Thraxles also serve those who fetishize stiffness. I’m not one of them, but I don’t argue with them about it either. Thraxles are stiffer. Do you want that? Maybe. Maybe not.

There is an element here, too, of  product liability reduction, as manufacturers work their way through the massive quick release skewer recall.

Of course, part of the challenge of moving to a new axle platform, and the main source of my frustration, is that it synchronizes with so many other standard changes (e.g. tapered forks/headsets, electronic shifting, press fit BBs, etc.), so that our parts bins and spare wheels become vestigial to the whole process of upgrade and afterlife (one of my favorite hobby horses). Another challenge is settling on a standard, 12mm or 15mm, until some a-hole decides 13.5mm is best. You know that’s coming.

This week’s Group Ride asks, do you thraxle? Do you own a disc brake bike that isn’t a mountain bike? Or, are you disc-skeptical, and thus thraxle-opposed? Is this just the industry selling us something new? Or slowly solving a real problem, answering a real need?


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  1. Andrew

    1) I have not thraxeled. But I would be willing to thraxel, with a kind and supportive guide. But only in states where thraxeling is allowed.
    2) I own a (gravel) road bike with Hy/Rd disc brakes. But no thraxels. It brakes fine. So does my road bike with calipers, even in the rain. That one doesn’t have thraxels either. The disc brakes are most worth it in the winter, because they don’t ice up and I can fit studded tires.
    3) They’re always trying to sell you something new.
    4) I’m sort of a disc agnostic. They work fine. I have never had a problem with calipers or cantilevers on road, mountain or gravel.

  2. Fuzz

    My new Roubaix came with 12mm thru axles. I absolutely love them compared to a QR. No more lawyer tabs and fussing with the QR, trying to figure out how tight to make it. Just spin it on and spin it off, and there are no axles in the way when you are sliding the wheel in and out. The rigidity ensures the rotors never rub. If it were an option, I would choose them with or without discs, for any bike.

  3. Alex Hillis

    I have a steel Waterford CX bike with discs. It was built in 2011, so I’ve got standard QRs instead of a ‘thraxle’. I don’t feel likeI need anything stiffer, but I’m also not racing. I’ve also yet to experience any brake rub under power, in part I think to the great adjustability of the Avid BB7 SL road calipers I user. And since I use the same frame for touring (outfitted with a front rack & frame bags), I’d feel much better about my chances of finding a QR in a local shop wherever I am than a thraxle if something goes wrong.

  4. Ransom

    I very nearly thraxled (and discussed discing but decided to discard) on my new build, but opted for the lighter weight and at least apparent simplicity of standard brakes and QRs for a nice-weather road bike, even though I do live in an area with Hills (and even Mountains).

    I wish my ‘cross/commuter/rain bike was equipped with discy thraxles (if only because I suspect the thraxles cut down on disc-ticking), and am happy to have them on my mountain bike, even if I did have to go buy an adapter to put it on my friend’s fork-mount roof rack.

    Speaking of stiffness, I don’t suppose anybody’s addressed in any depth the stiffness/compliance possibilities of getting equivalent handling out of a more compliant fork via thraxles, not entirely unlike the way the axles keep the fork legs in unison on motorcycles…

  5. hoshie99

    I got my second ever cross bike in 2012 and the frame is disc compatible. Instead of upgrading the fork , wheels and brakes to discs, I switched my cantis to mini vs (TRPs) last year which have plenty decent stopping power.

    So would I disc and thraxle? Yes, if I were investing now. For off-road or mixed terrain bike, in the hot dry skree and major peaks and descents of SoCal, I can see that advantage of discs and thru-axles. I certainly experience the benefits on my mtn bik. On a pure road bike, not seeing the need as much yet


  6. Rod Helm

    I have thraxles on three different mountain bikes, two of which are rigid (one fat). For off-road use, I consider thraxles superior in all respects to the old 9 mm QRs, particularly with respect to steering accuracy, but also for the elimination of any worry of a wheel coming out of the fork. That said, I have two disc brake gravel bikes with robust steel forks and QRs. I’ve never had an issue with rotor rub on either, and they have been raced and ridden hard over rough terrain. My next gravel bike will have thraxles, but I think they’re only necessary in non-mountain bike applications when the frameset is lightweight to the point of needing reinforcement to avoid excessive flex.

  7. Nik

    My mountain bike (with disc brakes) has QRs and my road bike (also disc brakes) has a thru-axle.
    The cheap crappy QRs that Specialized used on the mountain bike were so bad (external cam) that I had to buy some proper Shimano XT QR skewers. That helped a lot.

    I prefer the thru-axles because I can remove a wheel and put it back without worrying about the disc rubbing on the pistons due to some slight misalignment. On the bike with QRs, there is a good chance that the disc will go “zing zing zing” after removing and reinstalling a wheel.

  8. jim

    When I built up my new bike, it had a tapered head tube but I wanted to reuse my old Wound up fork. Luckily there is a Chris King headset that supports this. My bike is thru-axle on the rear and QR on the front. The Wound up is plenty stiff and the disc brake never rubs. The thru-axle is definitely an improvement on the rear. I suspect the full carbon forks benefit from thru-axle.

    Standards change and mix-and-match only lasts so many generations. When the woundup gets to a ripe old age, I’ll probably go with a Whiskey fork or equivalent and will switch over to thru-axle.

  9. Champs

    Tires and rims already have a purpose. Why wear them down for braking when a simple rotor would do that single task very well?

    We are not an exclusively disc brake household, but all of the wheels are QR. That was fine until The Hybrid From Hell came along and multiple mechanics struggled to get the rub out after taking the wheel off and putting it back on again. Since then I have figured out its nuances, but never again will anything less than TA be accepted.

  10. Andrew

    I’m pretty sure that’s why bicycle through-axles/thru-axles/thraxles were devised; to better constrain together the travel of the two sides of the fork on mtb suspension. Particularly for top-end downhill bikes when “upside-down” fork designs came in to use.

    It’s an interesting question though; could “noodly” rigid forks be improved with a through-axle system? The engineer in me says through-axles would only be of benefit when the fork was under loads that misaligned the dropouts. Either sideways loads bending the fork legs to the side, or twisting loads pushing one fork leg backwards (and the other bending/resisting forwards).

    For sideways loads (such as cornering forces) I suspect better structural performance for weight would be achieved with stronger fork legs. Which would also improve rigidity against twisting loads.

    The only significant twisting loads I can think of that would occur on a rigid fork is the torque applied by a disc-brake. (which is why through axles are also spec’ed on “normal” suspension forks where the bridge between the fork sliders ties them together for suspension movements.)
    Now, what were we talking about again?

    1. Stephen Barner

      If we make a comparison to distance, the design goals of marketing and reduced liability are arms length for through-axle systems on road bikes, while those of ride improvement are somewhere on the other side of the planet.

  11. Lyford

    My mountain bike has a QR fork and thraxle rear. I seem to be constantly chasing small disk rubs in the front after removing/reinstalling the wheels while the rear is fine. Going to a 9mm ratcheting skewer helped. I’d need a lot of persusion to buy a new bike with disks that did not have thru-axles.

  12. Aaron J. Humphrey

    My disc road bike had a bit of flex which created a bit of disc rub. I built new wheels with 9 & 10 mm thru axles (DT ratcheting skewers) and have been very pleased with the result. Since they work in standard dropouts, there is a pathway for older disc frames to get a benefit. As far as I know, only DT and American Classic road hubs are able to use adapters to change from traditional skewers, or at least that’s as far as I looked. Those plus TRP Hy-Rd brakes have been great on pavement and gravel.

  13. Jeff

    We built a tandem last year and went thru-axle because it should be (but no real data) more robust. Tandems have increased rider weight and larger rotors so it makes sense. We are on 15mm but someday may wish the 12mm stuff had sorted itself out.

    For single I am waiting for flat mount be widely available and decide what to build around.

  14. W

    I have 3 thraxle bikes and 3 qr bikes. Discs work better then rim brakes–end of story–therefore thraxle is the way to go.

  15. Craig P

    I have two road bikes with disc brakes and QR’s. I really don’t notice any disc brake rub on either. I feel it’s sort of a non issue on my bikes anyway. I’m going to ride the hell out of them for the next ten years!

  16. bryand

    I do not thraxle. I live in Vermont and ride plenty of mountains or even just punchy very steep hills. My road and cyclocross bikes all have rim brakes; I have several very nice wheelsets that aren’t thraxle either. and I’d like to continue using them. I am looking to purchase a (most likely custom because it doesn’t exist at retail) new frame that allows for fenders, shorter chainstays and conventional brakes without being a “gravel grinder”. My mountain bikes have had hydraulic discs for years, yet no thraxles. My roof rack on my car is still conventional QR too

    I don’t feel like I’m a luddite, but as a guy in his mid 40s who still goes pretty good I just don’t feel that everything needs to be stiffer or overbuilt in order to be “better”.

  17. Shugg McGraw

    Just bought a Focus Cayo Aluminium Disc 105 2016 (I liked the name). It has fantastic thraxles. No idea if it is stiff or not or what that means. It is just very satisfying to fit the wheel in a binary way. It’s in or it’s not. Very neat.

  18. Tom in Albany

    This thraxle discussion reminds me of the time my cousin popped a wheelie and his front wheel fell out. It ended suddenly and with a thud…

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