12mm Thru Axle for Kid Trailer

(50 customer reviews)

$ 58.00

Robert Axles for Kid Trailers are designed specifically to fit your 12mm thru-axle bike and allow attachment of any hitch-mounted trailer. These fit any trailer that has two wheels and a single point of attachment to the axle. This includes all the two-wheeled child, pet and cargo trailers such as: Thule, Chariot, Burley, Instep, Carry Freedom, and many more.

Purchase our Kid Trailer axle for your bike. Share your stoke for cycling with your kids. Simplify your life by allowing quick and secure attachment of your trailer to your best and favorite bike. Enjoy the adventure.

  • Compatible with SRAM UDH and Transmission.

In stock

Get 20% Off Lightning Bolt-on Axles With Purchase of Any Trailer or Trainer Axle! Discount Automatically Applied.
SKU: KID226 Category:


Since 2013, we have been an important part of cyclists’ adventures all over the world. Our axles have millions of miles on them in mountain bikes and road bikes, carbon bikes, fat bikes and e-bikes. Our axles are specifically designed to handle the high-torque loads generated by e-bikes.

Your stock thru-axle is not strong enough to haul your precious cargo! Our axles are 3 to 4 times stronger than the stock axle that came with your bike. Our stainless steel axle ends provide a safe and secure attachment point of the hitch to the axle. The axle is quick to install and remove with a common 5mm hex key.

Our axles are not just designed in the USA, but are made here as well. They are machined by avid cyclists to the tightest standards in the industry. We safety test, to failure, every batch of axles we produce to ensure they exceed your expectations.

Prop65 Warning icon

WARNING: This product can expose you to chemicals including nickel acetate, which is known to the State of California to cause cancer. For more information, go to www.P65Warnings.ca.gov.

Additional information

Weight 0.3125 lbs


Robert Axle for Kid Trailers replaces your stock thru-axle so you can attach a child or cargo trailer to your 12 mm thru axle equipped bike.

  • This axle is compatible with Burley, Carry Freedom, Chariot/Thule, Croozer, Instep, and many more hitch style trailers.
  • The diameter of this axle is 12 mm and the true length of the axle shaft is 184 mm. Spacers included for a 169, 175, or 184 mm fitment. Please note: Thru-axle lengths do not equal hub standards. An axle has to be longer than the hub to fit in the frame. A 12×148 hub does not equal a 148 mm long axle. We suggest a +/- 2mm axle length fit is perfect for all our axles.
  • This axle has a 1.0 mm thread pitch.
  • The axle shaft and axle end are precision CNC machined.
  • The axle shaft is 7075 aluminum and hard black anodized for rugged durability.
  • The axle end is stainless steel, which allow for mounting of the hitch provided with your trailer. The threads are M10x1 (metric).
  • Hardware for attachment of the hitch is included; the hitch is not.
  • No special tools required. Design allows for installation or wheel removal using your standard 5mm hex wrench.
  • Designed, built and quality tested in the USA. Proven around the world.


Need more information about how our axles work?

50 reviews for 12mm Thru Axle for Kid Trailer

  1. Joel

    Great solution to using a modern bike for a trailer hauler! Why trailer companies haven’t progressed is beyond me. Works flawlessly with my Thule child trailer.

  2. Kruse Markus (verified owner)

    Fits perfectly with my Trek Rail 7. Top quality, very fast shipping! 👍🏻💪🏼

  3. Chad Stronge (verified owner)

    Worked great. Installation was simple, shipping was so quick! Tha Canadian money conversion with shipping made it pretty expensive but it solved my issue.

  4. Derrik Schweppe (verified owner)

    Love this! Now I can pull my kids around the neighborhood on my bike. They love it! Seamless install, super easy to use.

  5. Stephan (verified owner)

    fits perfectly, was shipped within 3 days to Germany. thanks for this awesome service!

  6. Fredy monsalve (verified owner)

    After purchasing the 12mm thru axle for my daughters chariot it has a few issues. After greasing the axle and replacing it with my original axle I could not get it to losen up even tho I greased it and put it to the correct torque it would not let go. The 5mm hex option stripped the end and now I’m only left with my jaw locking pliers which is kind of a pain. Wish they had a different option like using a wrench.

  7. Fredy Monsalve (verified owner)

    Wow I’m speechless in less then 10 hours they wrote back to me and are replacing my axle under warranty. I can honestly say this caught me by surprise. Amazing customer service from these guys!!!! Keep it up guys

  8. Adam Reininger (verified owner)

    Awesome! Works great with my Thule Chariot (double) and my 2020 Trek Rail 7. Took the kids on long ride last weekend and they had a blast. Thanks for making such an amazing product.

  9. Dmitry

    5-star service throughout the whole journey.
    1) I got the consultation through email. I was waiting not more than 15 mins for answers.
    2) I got my order verified quickly.
    3) The delivery was really fast.

    I would recommend The Robert Axle Project to everyone.

  10. Asher Vitek (verified owner)

    I was super pleased to find this. We had been looking for a solution to pulling our chariot on my bike and this nailed it. Used the axle finder to get the exact axle I needed.

  11. Ramon Brendel (verified owner)

    Very happy – ordered from Germany and recieved within 4 days – fits perfectly with my Scott e-fully – thx

  12. Pete Wachowiak (verified owner)

    Works great on my Trek Rail! So glad to find this.

  13. Stefanie (verified owner)

    Im impressed. The search tool is so easy to use and accurate and found the exact part I needed. Even my local dealer told me there was nothing to do to attach a child trailer to my mountain bike and here the RAP has saved the day! Thank you!

  14. Johanna (verified owner)

    Works perfectly with my Canyon Spectral:ON. The axle was easy to install with clear instructions – even for me! The shipping was amazingly fast. Great customer experience overall, I highly recommend!

  15. Steven (verified owner)

    Very surprised about the great fit and high quality of the axle. Very happy I went with RAP.

  16. Larissa (verified owner)

    Fits perfectly on my Trek Rail 5. Ordered it from Switzerland and recieved within a few days. Very glad to find this axle. Thanks!

  17. Steve Howson (verified owner)

    Tell them what bike you have and they’ll send you the axel you need. They guarantee it. Installation was easy.

  18. Teemu Mikkonen (verified owner)

    Lightning fast delivery and a great product.

  19. Maxim Cloutier (verified owner)

    Great product. Fairly simple to install for soemone with little knowledge working on bycycles. Fits perfect and shipping was super fast. Thank you for the great product and service!

  20. Arto (verified owner)

    Shipment was fast. instructions were good and detailed. axle fit perfectly to my Trek Rail 5.

  21. Christian Jæger Denmark

    Genius. Plain and simple.

  22. Tyler Knibbe (verified owner)

    I was super frustrated trying to find the right axle that would work with my bike and Thule Chariot. I spent hours on the internet and phone trying to find the right specs, thread count, and trying to understand something I never have dealt with before. I finally reached out to a buddy that knows bikes better, and he immediately recommended Robert Axle Project. 10 minutes later the axle was on its way due to their awesome Axle Finder app. It was on my bike a couple days later and I was cruising around town with my boy. I just wish I knew about them before…

  23. David DeWeese (verified owner)

    Great product, so glad I found your company! I bought a 2021 Trek Fuel EX 8, and wanted to continue to tow our two boys in our Burley Bee. Your axle fit perfectly, did it’s job! Will recommend to anyone in need.

  24. Christian (verified owner)

    Great product and great service. ÅFits my 2021 Haibike Allmtn 6 with Thule Chariot kid trailer. Bike was not listed in axle finder app, but order was manually checked. They even asked for specs and pictures of original bike axle so they could add it to their database.

  25. Marco (verified owner)

    Super Service und passt perfekt für mein Lapierre Overvolt 6.6👍🏻
    Der Versand hat 2 Tage gedauert

  26. Eric (verified owner)

    The axle works perfectly for my Trek Rail 7. The Thru Axle Finder was easy to use and the axle is very high quality.

  27. Eric (verified owner)

    Perfect fit, easy to install. Very clear instructions.

  28. Robert (verified owner)

    High quality, light weight. Perfectly fit for my Haibike. Fast shipping to Norway.

  29. Cameron (verified owner)

    Perfect fit!
    Now we can get the kiddo out for family bike rides and spend more time together.
    These guys have gone above and beyond in identifying and fulling a need that has been overlooked. I’ll definitely be buying from them again in the future and recommending their products to friends until then!

  30. Andrew J. Bailey (verified owner)

    I got the 12MM THRU AXLE FOR KID TRAILER to add to my AZUB ti-fly x recumbent trike to allow me to pull a dog (formerly kids) trailer and a cargo trailer. It shipped quickly and attached flawlessly. Thanks guys!

  31. Hooman Tabarestani (verified owner)

    I bought this Axle for the future as I want to buy a two-wheel trailer to carry my kayak with it.
    I already have a single fat wheel trailer, which I bought a BOB trailer’s Thru-Axle and Hardware-Kit for it, so I purchased this Axle simultaneously as I knew I was going to need it soon. As a result, I haven’t used this one yet, but I am sure it will do it and solve my problem as the other Axle and kit already did for my single wheel trailer.

  32. Keith (verified owner)

    Fit perfectly on our Trek Powerfly.4 FS. EBike is a perfect way to tow a Burley dog trailer, and Burley didn’t make the size / thread configuration we needed.

    Shipping was quick and their website information helped ensure I ordered the correct axle.

  33. Zack Higbee (verified owner)

    The instructions were very helpful. Easy to swap with my axle once the sizing was set correctly.

  34. Kent

    Shipped to Canada lightning fast over a weekend. Fit perfectly. The selector works. I feel good that I was able to get a 12mm axle so I could use my cross country bike. Went out on our first ride and everything stayed secure. Thank you for supporting different designs.

  35. Ross Marshall

    Fit my 2022 Azub Tricon trike perfectly. I leave the male adaptor on for my Raleigh trailer on to just plug in and go.

  36. Steve Tan (verified owner)

    Does the job, easy peasy. Why can’t more things in life be this straightforward?

  37. Jessica (verified owner)

    Perfect and fast shipping. I bought this for my Burley XL dog trailer and Specialized Fuse Comp 29 with the 148 boosted axle. The drop down menu to select the axle needed for my bike was very helpful.

  38. Jim H. (verified owner)

    Customer service was exceptional. I emailed them to ensure I was ordering the correct axle, and they replied within a few hours. Received the axles in 4 days. Perfect fit, and is very easy to install.

  39. Chad (verified owner)

    Great company! They very quickly helped me identify the part I needed, and sent me a link to order it. Extremely easy for a busy guy.

  40. S.russell (verified owner)

    Great quality. Bolts on no problem. Ultra fast shipping.

  41. Abe (verified owner)

    Team was very helpful. Fits my 2022 Spire alum like a glove.

  42. Timothy Eminger Jr (verified owner)

    Website is incredibly simple to ensure correct part for bike and the product quality is outstanding. I was able to add this to my giant fathom and pull my daughter around town and on trails in her trailer. Thank you Robert axle.

  43. Daniel (verified owner)

    Worked great with my Cube Reaction Hybrid from 2022

  44. G. Kelley (verified owner)

    Arrived quickly and in great shape. Fit my 2023 Trek Powerfly 4 perfectly and now the pups can go with us!

  45. Dave (verified owner)

    A bike store employee told me I could not install a kids trailer on my e-bike. I searched around for a bit and discovered RAP. Awesome website. Super easy to find what you need based on make/model. Shipping was fast and I had a new axle on my bike with Thule kids trailer installed only 3 days from placing the order. Works perfectly and super easy install on my Scott Genius E-ride. Thanks!

  46. Maria Hausdörfer (verified owner)

    Toller und schneller Service, einfach Kommunikation und sogar Nachfragen ob alles in Ordnung ist. Die Achse ist hochwertig. Alles super.

  47. Justas Liu. (verified owner)

    Great quility product. Fast delivery to europe.

  48. Tom (verified owner)

    Prefect fit!

  49. Danya Anderson (verified owner)

    Thank goodness for this product. How many bikes come with QR skewers these days?? Really quick, even to switch out a mis-advised size (ask via email for Giant bikes). High quality machining. Stoked!

  50. Philipp Putzer (verified owner)

    Fits perfect for my Radon bike with an old Chariot Kids Trailer with “Weber Kupplung”.

    Very fast shipping

    Thanks a lot!

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