Ever wonder why are thru axles different for every bike?

Why they’re different for road, gravel, cyclocross, mountain and fat bikes?

What’s the different between thread pitches? Why some are wider than others? The pros and cons of different designs?

All those questions and more, answered in this video with the pros at Robert Axle Project! We cover the complete range of thru axle options for all types of bikes, and explain why there are so darn many options!

Here’s what you need to know about Thru Axles:

  • Every frame and fork needs a thru axle with the correct length and thread pitch
  • Robert Axle Project makes replacement thru axles for most types of bikes, contact them for the right model for your frame or fork.
  • Or use their Axle Finder on their website.
  • They also make thru axles that let you attach trailers and stuff to your bike.
  • Finer thread pitches (like 1mm) take longer to thread in, but hold more securely.
  • Courser thread pitches (like 1.75mm) tighten faster, but won’t hold quite as tight.
  • Some bikes, like Trek’s Split Pivot full suspension bikes, use thru axles that are up to 50mm longer than the hub dropout width.
  • Most every modern disc brake road, cyclocross and gravel bike uses a 12×100 front hub standard, and a 12x142mm rear hub standard.
  • Mountain bikes have a lot more variation, but most modern bikes are at least Boost 12×148 rear, with some getting 12×158 Super Boost. When mountain bikes first went to thru axles, the standard was 12×142, which was the same effective width as the Quick Release hubs they replaced.
  • Early cyclocross bikes borrowed the 15mm front thru axle diameter, but as disc brakes became more common on drop bar bikes, they all standardized to 12mm.

The most important thing to remember is that you need to order the correct length and thread pitch if you’re upgrading or replacing your thru axle.

Huge thanks to Robert Axle Project for supporting this video!


DISCLOSURE: Yes, Robert Axle Project chipped in financially to help produce us produce this content.


  1. With quick release there was something sticking out on the sides of the bike that took the impact if the bike lands on its side protecting the frame and drive train. With thru axle this doesn’t exist any more. If you get a thru axel with a lever the lever protects that side of the bike but how come no longer thru axles that would stick out a cm or so to help take the impact?

    • A few reasons. Quick releases probably don’t actually offer much benefit in that area: handlebars and pedals stick out further and that quick releases won’t really absorb energy. Thru-axles without levers or handles are lighter, simpler to manufacturer, more aerodynamic, and look better. (Shimano’s design philosophy has been to make everything more narrow and inboard to protect frame/components, so maybe there’s something to simpler and more compact.)

  2. Unfortunately they don’t make a 20 X 165 to replace the crappy Maxle Lites made by Rockshox. Nobody does. Thus one is stuck with the really crappy lever Rockshox designed.

  3. So if my road bikes are 10 years old and use axles w quick release I can’t use a modern thru axle correct? Frame and form don’t have threads..

    • You can go halfway with DT Swiss’ RWS axles. You would still need compatible hubs. For a road bike, probably not worth the money, but it’s an option.

      • Agreed on RWS working really well. The other option is a a skewer that tightens with a 5mm hex wrench. Super cheap (~$15 for the pair on Amazon, can find them in a ton of places) and allows you to get as much torque as you want. Side note: that’s what I use on my direct-drive trainer to help eliminate any movement, wear, and creaks.

  4. Thru Axles without a lever to put pressure on the threads of that axle concern me. I have seen this type of axle back its self out of a rear drop out. Luckily the person I was with stopped before it came all the way out. We tightened it back up, very tight and a little bit further down the trail it was loose again. Scary. Why should I trust these? Anyone?

    • A lever isn’t needed to ‘put pressure’ on threads. That’s what tightening does. You just have to be sure to tighten the thru axle correctly and as with all fasteners, periodically check to be sure it’s still tight. If you saw an axle like this back out, it likely wasn’t tightened appropriately and/or checked.

      • Well, if you buy into the gospel of Eli from the very first comment, it’ll magically save your frame from any type of damage in a fall, make you more attractive to the opposite sex, and increase your odds of hitting the Powerball numbers 274%.
        I know I’m on board!

      • A QR lever typically has a cam action. If closed correctly, in order for it to open again it actually has to go through a position where it is tighter first, which prevents the lever opening by itself. The inner face of the QR meanwhile can have a knurled surface which binds against the outer face of the dropout, preventing easy rotation (unthreading) until the lever is opened. This very effectively prevents the system from coming loose accidentally (thanks Tullio).

        Of course this isn’t the case for the popular DT RWS design where the lever simply allows you to tighten the thread (and reposition the lever afterwards). The ‘Maxle’ design is far superior in this respect.

        FWIW I’ve been running a DT RWS on the back of my MTB for 7 years and have never had it back out, so it’s not a problem I’ve encountered in the real world, but I’m still happy that my Fox fork has a 15QR axle instead.

  5. I miss having a lever on my TA. Now I have to carry a tool with me everywhere. Buying new axles with a lever is an expensive upgrade.

  6. Sad commentary about the loss of a rational industry standard. QR was perfectly fine for any bike other than DH. Now it’s a mess.

    • @ People Power: The downside of QR is that rotor/caliper alignment isn’t always great with disc brakes, where that’s not an issue with thru-axles.

      The downside of thru-axles is that the dropouts themselves are threaded, so if those ever get damaged (rare but possible) you are in a world of hurt.

  7. Disc brakes with QR was just awful. Yes, the bike industry has, once again, introduced a multitude of fresh new standards, but I really dislike wrestling with the qr/disc combo. TA solves ALL that crap. I’m a convert. Never have come loose, have never had a problem. Unless my thread pitch is discontinued, I don’t anticipate one….. The bike gods nailed this one.

    • Agreed – Discs with QR required a lot more fiddling than I cared – tilt a little bit, no a little bit less… there, centered! Now tighten it…ah crap, hit a big bump in the ‘cross race, now we are rubbing.

      I’d still pick the discs for all off-road activities.


  8. Sorry but I don’t know what the problem is. Been using discs forever with QR…no issues with alignment. Maybe your dropouts were messed up?

  9. Well I guess if the former is a problem, one should also use QR levers on the Stem, the handlebars, the crank, the saddle and all the other parts where these untrustworthy threaded connections are made!

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