The PDXTI 12-15-TA-Adapter itself is compatible with all 12mm Thru Axle forks and all 15mm Thru Axle hubs. And while a wide range of forks and hubs work together perfectly, certain combinations of 15TA hubs and 12TA forks have compatibility issues.

Please note that the critical dimensions for compatibility are the inside diameter (ID) of the fork dropout pocket and the outside diameter (OD) of the hub end cap. In practice there are no standards in use for either dimension.

A wide range of 12TA forks have 20mm-21mm ID dropout pockets that accommodate the majority of 15TA hubs. A smaller subset of 12TA forks have 19mm ID dropout pockets that accommodate fewer hubs. For a

There are a few outliers that are smaller but most 15TA hubs have an end cap OD of ~20mm. This creates obvious compatibility issues with the aforementioned 12TA forks with 19mm ID dropout pockets.


For those upgrading an existing bike who do not already have a 12TA fork and are looking to skip a lot of the hub drama, the REN GX1 is highly recommended. The dropout pockets, shown below, have an ID of nearly 21mm, and the fork has a sweet 50mm offset, full carbon tapered steerer, integrated fender mounts, and optional titanium front rack.

For those with existing 12TA forks who want to find out if a specific hub will play nicely, first measure the ID of your fork dropout pockets.

  • Measure the diameter of the pocket across the centerline of the dropout hole.

  • For an accurate measurement of diameter it is critcal that the measurement be taken across the center.

  • Some dropout designs do not have a full half-round pocket which can make an accurate measurement difficult. In these instances use your 12TA axle to help accurately locate the axle center, and measure to the top of the dropout pocket.


To check hub compatibility, measure the OD of the axle ends/end caps.

If the hub end OD is smaller than the ID of the fork dropout pockets there are no compatibility issues and the PDXTI 12-15-TA-Adapter is all that is needed, just plug and play.

If the OD of the hub axle ends is larger than the ID of your the dropout pockets there is a basic compatibility issue.

Forks, especially carbon fiber, are complex monocoque pieces of engineering that don’t lend themselves to modularity or modification. Hubs on the other hand are generally able to be disassembled and afford several possible compatibility solutions.


First, a standard 12mm end cap conversion kit may be available from the hub manufacturer. Problem solved.


If there is no standard 12TA conversion kit available don’t fret.
PDXTI stocks complete 15TA hub conversion kits including the axle adapter and 12mm fork compatible end caps available for several popular models from DT Swiss, Race Face, Chris King, and Mavic.


For other hubs with end cap OD greater than 19mm PDXTI offers a conversion service for most hubs that includes the 12-15-TA adapter. Please inquire about your specific setup and we are happy to help.