Note: This guide references our CargoPack – formerly known as the AeroPack.
Introduction
Labelled as ‘maybe the most fun bike they’ve ever made’, the Specialized Diverge has made its way to being the people’s favourite for gravel rides and bike-packing trips. Many of our Tailfin customers use this bike, and it is one of the most searched-for models.
The Diverge is currently available in alloy, carbon and also offers an ‘STR’ version. The frames have undergone some changes since their introduction. This guide will show how to fit a Carbon CargoPack to the Specialized Diverge Expert Carbon and applies to the other Diverge models too.
This blog features a 2025 Specialized Diverge 4 Sport Carbon in size 54cm.
Configure your Tailfin Order
In this example, we’re showing the Fixed Carbon CargoPack with pannier mounts, but our Alloy versions (and our Pannier Racks) are also compatible with the Diverge. The suspension system used on the ‘STR’ models has a relatively small amount of movement. Both the CargoPack and Pannier Rack are safe to use and can pivot to accommodate this movement. For full-suspension bikes, or when riding rougher trails, though, we recommend the Fixed CargoPack/SpeedPack System, or Pannier Rack without the removable CargoPack/SpeedPack Rack Top Bag.
See our comparison guides to help choose which setup is best for you based on your riding plans.
Choosing the Right Axle
We recommend ‘Axle Mounting’ for the Diverge, as frame mounting is not possible on this model. The thru axle mount eliminates almost all the stresses on your frame. It is the mounting approach we recommend above all others.
The 2025+ Diverge Carbon frames require a Universal Thru Axle (which includes the required 1.0mm thread pitch) and also the Tailfin UDH/Transmission Adaptor (the exact adaptor will be determined by the groupset fitted to the bike).
Specialized have maintained the same axle type for many years, since switching to the Thru Axle version in 2016 and UDH frame standards in 2025. Older models require the QR Axle, which is selected during the ‘configure’ process of your Rear System.
Before placing your order, use our Axle Guide to search for your bike and see if any additional adaptors are required.
We also recommend choosing the Universal Thru Axle over the Single Thru Axle as it provides the option to add up to 16mm of extenders in the centre – making the axle wider to accommodate the wider T-Type SRAM Transmission Derailleurs (common on the 2025+ Diverge models). The carbon and alloy arches accommodate this additional flex by design, too.
Included in your Universal Thru Axle box is a single non-driveside part. Then, you have the four driveside parts covering the most common thread options of 1.0mm, 1.0mm ‘speed release’, 1.5mm, and 1.75mm. You can change the ends and fit your Rear System to other bikes, too.
Assembly
Use our Assembly Guides to put together your CargoPack. You’ll need a Torx T25 tool and a torque wrench to do this.
Fitting
Now your CargoPack is assembled, just one part remains – fitting it to your bike. To do this, you’ll need to install the new Tailfin Universal Thru Axle and UDH Adaptor.
You can leave the axle fitted even without the CargoPack attached. It’s normal for threads to show on the drive side – it is just as safe as your original axle, as the number of axle threads engaged with the frame is the same.
Follow the steps below to fit your Universal Thru Axle and UDH Adaptor to your Diverge
You can also follow our video guides below:
Attach your CargoPack
The last step is to attach the CargoPack to your Diverge. It’s often easier to do this standing behind your bike.
Close the Fast Release Dropouts around either side of the axle and secure the Seat Post Connector in place, ensuring it’s locked shut. Choose the long seatpost strap if your seat post is ‘Aero’ or ‘D-shaped’.
See our quick video guide on how to correctly attach the Seat Post Connector.
Now you’re ready to ride!
Optional Extras and Additional Products
You can choose to add extra items to your setup to make the CargoPack best suited to your needs. Our Adjustable Light Mount and Mini Cage fit the rear of the CargoPack, and if you use the Garmin Varia Radar system, then you will require Garmin’s Seat Rail Mount to fit it to the top part of the Adjustable Light Mount fitting.
The alternative 10L SpeedPack has a smaller capacity for a lighter weight, ultra-fast set-up (shown in this guide).
However, if you wish to add additions to your set-up, consider these options below: 3L Half Frame Bag, 22L Pannier, 18L Fixed CargoPack, and 1.6L Long Top Tube Bag
