Review: PDXTI 12mm to 15mm Thru-Axle Adapter – Simple solution to an annoying problem

PDXTI is Portland Titanium

PDXTI is the brainchild and one-man crew of Eric Herboth, co-owner of and worker at Eric is an enterprising fellow and noticed a void in the market for parts such as axle adapters, titanium headset spacers, headset caps and 3D printed parts. Thus, he decided to do something about it… but first, a little info about those other two companies Eric is involved with.

Ti Cycles Fabrication has been in business since 1990, and is renown for building anything you want in titanium or steel. Bespoke / Custom aka “Built In The Woods”, all of their frames are built in Portland, Oregon.

Ren Cycles draws on Ti Cycle’s 35+ years of fabricating experience to bring the virtues of premium materials and performance together, with the passion and practicality of everyday cycling. In a nutshell, Ren produces production frames and bikes at an attractive price point with options for customization.

One of the parts from Eric’s PDXTI operation is the 12mm to 15mm thru-axle adapter. If you own a bike or two, a wheelset or two, or if you’re like me and you review multiple bikes and wheelsets at any given time, you’re well aware of the different standards the bike industry has on offer.

In the world of thru-axle disc brake bikes, whether they be road, mountain, cyclocross or gravel, there are two standards that apply – the Boost standard is not part of this discussion. There is the 12mm thru-axle and the 15mm thru-axle. Both are designed to safely pair your front wheel with your bike’s fork.

Generally, 15mm has been a mountain bike size, and with the development of disc brake for road bikes, 12mm has become the road standard. Gravel bikes seem to be a mix of both sizes, whereas most cyclocross bikes utilize the 12mm standard. The trouble is, with two standards, it would be ideal if wheels between all bikes are universally compatible.

A lot of wheel companies make available different end caps or axles for both axle sizes, but not all. You can see where I’m going here…

PDXTI 12mm to 15mm axle adapter review

Pictured above is Litespeed’s Carbon Gravel fork (link here to my Litespeed Ultimate G unboxing video), designed around the 12mm thru-axle size.

Because I’m always swapping wheels and tyres between the various review bikes I have going on. the different axle sizes have proven to be a real problem. I wanted a solution to this problem, but without always having to resort to a different send of axle end caps.

Before I go any further, this solution will only work on front wheels designed around the 15mm front thru-axle.

PDXTI 12mm to 15mm axle adapter review

Pictured above is a review wheelset, Industry Nine’s 700c TRA. The company supplied me with two sets of end caps for my review wheelset, but swapping end caps isn’t always conducive, especially if you don’t have a tool or the hand strength to remove the end caps.

PDXTI 12mm to 15mm axle adapter review
PDXTI carbon 12mm to 15mm thru-axle adapter and shop towel.

This is where PDXTI’s carbon 12mm to 15mm thru-axle adapter comes in handy. Weighing a paltry 9.7 grams, this simple tube of carbon fiber slides into your wheel’s 15mm front axle, spacing out the front axle and allowing you to utilize a 15mm thru-axle front wheel on a bike designed for 12mm.

PDXTI 12mm to 15mm axle adapter review

The PDXTI adapter is constructed from 3K precision rolled carbon fiber, measuring 15mm x 12mm x 99mm. It is slightly undersized by 1mm in width, to ensure an interference-free fit with all possible combinations of forks, hubs, etc.


  • Apply a thin layer of grease to the PDXTI 12mm to 15mm thru-axle adapter, and your 12mm thru-axle.
PDXTI 12mm to 15mm axle adapter review
Litespeed gravel fork with DT Swiss 12mm thru-axle.
  • Slide the PDXTI 12mm to 15mm thru-axle adapter into your 15mm thru-axle hub.

PDXTI 12mm to 15mm axle adapter review

PDXTI 12mm to 15mm axle adapter review
PDXTI axle adapter installed and ready to go.
  • Install the wheel into your fork, then install your thru-axle.

PDXTI 12mm to 15mm axle adapter review

Go ride!

PDXTI’s simple solution to an annoying problem has proven noise and trouble free during my period of review. Because there is the risk of galvanic corrosion between a carbon tube and aluminium axle, I recommend you remove the wheel and axle adapter on a regular basis as part of your routine bicycle maintenance. Apply fresh grease if needed.

PDXTI 12mm to 15mm axle adapter review
Litespeed Ultimate G review bike.

PDXTI’s 12mm to 15mm carbon thru-axle adapter costs $US 19.00 and is available now.


8 comments on “Review: PDXTI 12mm to 15mm Thru-Axle Adapter – Simple solution to an annoying problem

  1. If I’m not mistaking, a fork designed for 12mm thru axle will not willingly accept a 15mm axle. The OD of the 15mm axle does not mesh with the radiused internal portion of the fork.
    My envy cross fork has a half Moon scallop on the dropout to accept a 12mm axle end. A 15mm axle end is too large and would not sit flush with the dropout and would prevent adequate interface between the hub and fork.

    1. I’ve not experienced a single problem with any 12mm bike I’ve reviewed where I swapped end caps for a 15mm front wheel. Not all 12mm forks are the same.

  2. Funny, it’s been a year since i told Open cycle they should sell an adaptermade from alu or carbon.

  3. This is a neat solution when/If it works, but many 12mm forks have recesses that won’t fit the larger OD of 15mm end caps; Specialized’s Sequoia fork is an example. I guess the price is low enough that it’s not a huge deal if things don’t work out with one’s particular combo.

  4. Aaaaamazing!
    I’m building my new gr260 frame (Jom inspired) and was hoping to use some 27.5 (15×100 front) wheels I have kicking around. This opens up a ton of options 🙂
    Thanks for the always great info.

    1. As some others have noted, 15mm hubs don’t fit in all forks. On my wife’s Norco Search XR it’s a tight fit but works with the adapter. My Salsa Warbird cannot take 15mm hubs, the end caps are just to big to slide in the recesses on the fork. I do like these adapters though.

  5. Yep, I had the same problem – 15mm hub would not fit on my (Canyon) fork. Got the adapter, got all excited, then had to source some end caps for my axle.

    Also, I change front wheels a lot and I kept dropping this thing on the floor, so I used a dab of silicone on it to keep it in the hub when taking the wheel off. This was not a problem after changing to smaller end caps, although I did have to trim the carbon insert down to fit it between the 12mm end caps.

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