Why have we changed to Torx bolts?

Thanks to the clever modular nature of Tailfin products it is very simple to construct, maintain and repair your Rack or AeroPack. To help make this process as user friendly as possible we use interchangeable bolts to fix everything together with only a standard multitool needed to construct. We used to use bolts with a 3mm hex head but we’ve recently rolled out a new way of tightening the bolts, by changing to Torx heads.

What the reason for changing to Torx? 

Short answer: Torx are less prone to damage, providing a far more reliable long term fixing solution.

And the long answer?

For decades the standard ‘go to’ tool fitment of choice for bicycle components has been the hex head (or Allen head dependent upon your geographical location or upbringing). The six sided recess characteristic of this style provided a far superior level of tool security than a traditional screw head and enabled the installer to tighten up bolts with a fair degree of reliability and minimal slippage. 

But for all its advantages the hex head is not without its drawbacks. Top of the list is the potential to round out the fitting, rendering the bolt useless. Anyone that has tried to tighten or undo a stiff bolt in a hurry has probably unintentionally started to round off the sides of the bolt where the tool fits. This is compounded when you need to use smaller sized and low profile fixings such as we use on Tailfin products. In fact, rounded out bolts are probably the most frequent issue raised through our customer support service – hence our choice to change to a more reliable method.

The industry standard hex head on a button headed or countersunk M5 bolt (the standard measurement bolt style we use) is capped at 3mm. This is in order to retain as much metal and therefore strength as possible on such low profile fixings. While it does a great job of securing components together, smaller heads can be difficult to manufacture to very high tolerances. Despite us choosing the most expensive fixings we can afford there can still be some issues which can cause problems. Get the tolerance just a few micro millimetres off and the recess might not provide the perfect fit with your tool.

At this point it’s worth looking at the simple diagram below. Here you can see the difference between a hex head (on the right) and a Torx head. Torx bits have a higher surface area for torque application, as well as a 15º drive angle compared to the hex’s 60º which ultimately means increased tolerance, effectiveness and far less tool slippage. The green circle represents the ultimate diameter of the recess and you will note just how little material can be seen on the inside of the indicator on the hex head bolt.

Why have we changed to Torx?
Torx head versus hex head in terms of surface area, drive angle and how easy each is to ’round out’.

Unless the hex tool is inserted perfectly there is potential for it to lose grip on the bolt. If this happens then the tool can damage the inner surface sufficiently to prevent the tool from gripping, leaving the user unable to tighten or loosen the bolt and having to resort to drastic tactics in order to free the bolt. This can also be further compounded by the quality of tool used. A lot of cheaper hex tools found on multi-tools and as separates are not manufactured to the exacting tolerances of more expensive options and might also use a softer grade of steel. Both characteristics can accelerate and exacerbate wear on hex bolts.

What is Torx?

Torx is a trade name for the recessed six-pointed star shaped bolt we are now utilising on Tailfin products. As highlighted above it was developed to provide a higher surface area for tool engagement as well as the lower drive angle resulting in a system that limits slippage and increases tolerance and reliability. It was developed predominantly to work alongside the increase in robotic manufacturing as a more reliable fixing method for robots to use.

We feel that the move from hex to Torx eliminates one of the only potential ‘weak spots’ of the Tailfin System. We have opted to use bolts that have the standard T25 sizing, a size that many cyclists will already be familiar with as all disc brake rotors and quite a few stems are fitted with this size of bolt. Due to this widespread use you will also find that a large number of modern multi-tools come with a T25 tool as standard. So in the most part it should be a painless transition for most new Tailfin users.

We are rolling out the change to Torx heads over all Tailfin products in the coming months.

What if I want to change my existing hex head bolts to Torx?

The good news is all Tailfin bolts are a standard M5 sizing so can be replaced very easily with readily available countersunk Torx T25 bolts. These can be found in the majority of hardware stores or online and are simple to change at home.

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