Send me your seatpost shapes ... to build an Apple AirTag Mount

Hello everyone! When I finally received my Tarmac SL7 last year, I had trouble securely attaching my Garmin Varia to the aero seat post. In several stages of evolution and thanks to your suggestions, I was able to develop a suitable adapter. Due to your inquiries I have also developed adapters for other bikes. Thanks for your support!

Now I have a new project.

I have developed a silicone adapter that allows me to place an AirTag invisibly in the seat post. I would also like to implement this solution for other seat posts.

What I need is the contour of your seat posts. Can you send or post this to me?

All you have to do is place the lower end of your seat post on squared paper and trace the contour with a sharp pen.
Please also note your bike model on the paper.

As a thank you, I would be happy to send you a finished adapter if it can be implemented in your seat post.

I look forward to your questions and suggestions.



Great idea, one thing though. For bikes with Shimano Di2, thats where the battery sits most of the time…

Maybe the adaptor could be like the rubber grommet that holds the Di2 battery in place, but with added height to also fit the AirTag?

Another idea is to maybe build an AirTag holder for the Specialized saddles? They have he 2 holes at the back and with a bit longer screws, you could fit a little holder of the AirTag + some kind of accessory.


Hi Dubadai, i have to take a close look to the Di2 Bikes. For the specialized saddles i made two adapters. But every model is a little different. So it’s not possible to build a very clean integrated solution that fits to all models.


Amazing, looks great! :smiley:


Just an observation (happy to be corrected if I have this wrong) but you will be unable to get an AirTag into many typical road bike setups.

  • image

This 31.9mm diameter size is larger than the common 27.2mm round seat post diameter found in a majority of road bikes. That’s even before considering that your design fits inside a post, which would mean an even smaller diameter available.

Even the example you show with the Domane post above won’t work since it is smaller than 1.25" per the graph paper trace. The potential pool of compatible bikes/posts will likely be restricted to bikes with non-round posts, which means aero road bikes and TT/Tri bikes for the most part.

With that in mind, I do have another concept that could be worth considering, that would possibly allow for one insert design to fit multiple posts designs and sizes. I can model something quickly if you are interested.


Little piece of double sided tape inside some foam, put above the bottom bracket in the seat tube or down tube. Make them bring a bottom bracket tool to extract it.


Hello Chad, thank you for your message. You’re absolutely right, the solution will only work for aero seatposts. The sketch with the Madone is only intended as an example. By the way, the pictures above are of a finished solution for the Specialized Tarmac SL7. I build molds from the contour of the seat post and then cast the adapter. Works great. But since there are a variety of aero seat posts, I would be happy to see more contours.

1 Like

Sorry for my long delay in getting back, but here is a super quick model of my concept.

Essentially a semi-flexible material and shape that can bend as needed within a range to fit in some different shape and size posts. Precise dimensions on things like the legs would need to be set within some expected size range. It seems that something like this could fit several different sizes, such that it may take 2 or more overall designs / sizes to fit if there are large enough differences between the posts of interest.

But I think this concept could lead to far fewer total designs to make.


Very nice idea!

1 Like

THANKS! :smiley:

Here is an alternate to the “X” above with an “O”.

There are countless ways this might be mixed between the two, but my goal would be to make one or two designs that could serve multiple applications.

I’d love to see whatever you end up with even if these aren’t useful overall.

I love the idea! In thinking of metal bikes like my AL Domane wouldn’t something placed in the metal seat tube attenuate the AirTag signal? Maybe for those use cases an alternate location could be considered if it turns out to be true.

I’d like to help POC this :slight_smile:

1 Like

Yeah, I have no idea what comm issues would happen with various materials and a recessed location like inside the frame.

That looks awesome. You wouldn’t be willing to share the stl file would you?

Hi Steven,
Can I buy a few SL7 seatpost AirTag holders from you?
How can we arrange this?
Kind regards,

Hi Edwin, i’m sorry, the signal of the airtag is to often bad in the seatpost. So i did not produce them anymore.