Extended Top Stay – Product Design Notes

One size fits all is a philosophy that many products are based around and has been true to some extent for Tailfin’s approach to creating the perfect rack system. The dimensions of our Racks have been meticulously researched and tested to ensure flawless performance when fitted to the majority of bikes, regardless of size. But we do acknowledge that it is next to impossible to guarantee a perfect fit on 100% of bikes in all sizes.

Often riders with a low saddle height, dropper post or small frame can find access to the front of the AP20 Trunk Top bag compromised. As we already offer an extended seatpost connector for our AeroPack one of the most frequently asked questions from riders is when are we going to provide a solution for our rack systems. Well, the good news is the answer is now.

Tailfin Extended Top Stay

You are probably wondering why it has taken us so long to develop such a product when all it needs to do is place the bag a little further back and out of the way of the saddle. The answer is because we wanted to get it right. And it turns out that getting it right wasn’t as straightforward as you might think.

Fundamentally the new Extended Top Stay looks very similar to our existing standard top stay albeit with a bit of extra material and length at the front. However, a lot of engineering, sleepless nights and endless testing had to go in to make sure it works as we wanted and is strong enough to ensure carefree travelling regardless of load.

Why is it not just a simple extender?

In summary, this was the root of the challenge. The standard top stay was not designed to have such a high load placed so far away from the top stay “Union” (the point where the top stay splits from a single stay to a double stay). Adding an extender massively increases the stress at the union by around a factor of 3x which, under heavy loading or rowdy terrain, eventually results in failure. 

This therefore drove the design towards creating a brand new top stay with a stronger union. This was relatively easy (although expensive and time consuming) crafted in carbon fibre, however it proved to be considerably more challenging creating an aluminium version. The ‘nose’ of the aluminium top stay had to be completely redesigned to create a larger weld path to spread the load.

Our final issue, and one which created the longest delay and most headaches was the simple act of getting our factories to manufacture a completely new product during a global pandemic. With production being run to capacity as it is, introducing a new model was a very drawn out process compared to usual.

How much difference does the new top stay make?

Tailfin Extended Top Stay

The new Extended Top Stay provides 50mm of additional length and therefore positions the AP20 Trunk Top Bag 50mm further behind the saddle. We found this amount of extension provides an excellent balance between enhanced accessibility/increased bag volume and ride quality and load bearing. 

Who is it for?

The new Extended Top Stay is for any Tailfin Rack user who feel they need a little extra space behind the saddle when using the AP20 Trunk Top Bag. This is normally a rider who finds the front of the bag squashed underneath the saddle and suffers from reduced packing space. This might be because of a smaller frame size, lower saddle height or if you have a dropper post fitted to your bike. 

How do you fit it?

Fitting is simple.

To remove the existing top stay: A) Remove the Seatpost Connector using two 2.5mm hex keys (if needed). B) Pull off the rubber retaining clip found on each side of the existing top stay where it fits to the arch. Carefully prise the top stay off the mounting pin of the arch (don’t use too much force as you could potentially stress the top stay).

Fitting the new Extended Top Stay, attach the Seatpost Connector to the forward mounting hole (the bushings should already be installed), carefully push each arm of the top stay onto the mounting pin of the arch then ensure the rubber retaining clip is fully seated in the groove found around the mounting pin. Your new Extended Top Stay is now fitted and your rack is ready to use.

What are the buying options?

The Extended Top Stay will be available as a standalone product, requiring you to swap the Seatpost Connector from your current top stay onto the new top stay. It will be listed under the Spares section of our website. For riders wanting to swap between top stay lengths we also have the Seatpost Connector listed as a separate item in the Spares section.

Extended Top Stay weights and dimensions

Tailfin extended top stay

Alloy weights: 71.4g (short) 75.3 g (long)

Carbon weights: 47.7g (short) 51.9g (long)

Are there any differences in weight limits with the new extended top stay?

One of the fundamental parts of the design brief for the new top stay was for it to allow you to carry the same load as the standard version. This stays as a maximum recommended weight limit of 9 kg.

We do urge users to use some discretion and caution when loading for a trip dependent upon the surface covered. For road and smooth gravel you are completely fine to go to the maximum. For rougher gravel, singletrack and mountain bike trails we recommend a lower weight to be carried owing to the additional forces that are put on the bike on these types of terrain.

I’ve only just bought a Tailfin Rack with normal top stay, can I swap for an extended version?

Whilst we are selling the extended top stay as an additional item we are aware that there might be some riders who have just received a rack, haven’t ridden it and would ideally like to use the extended top stay. If this is the case we ask you to email [email protected] and we will go through requests on an individual basis.

To be the first to hear about our latest technical innovations or Tailfin interest features why not subscribe to our mailing list by filling in the form below.

Blog Post Signup Form
Riding Style