Liner Side Bites Fins Set - ST Box

Who is it for?

The Liner is designed for surfers who prioritize long lines and flow, while maintaining speed through the wave.

It suits intermediate to advanced surfers and requires a more committed, anticipatory style of surfing. It is less suited to tight, abrupt turns. This is a side bite built for smooth and fast surfing.

What is it for?

The Liner performs particularly well on fast modern longboards, mid-lengths, or glide-oriented boards. It excels in waves with open face, such as point breaks and long running sections.

What size?

In a 2+1 setup, the center fin and side bites work together. Their relative size directly determines the balance between glide, stability and manoeuvrability.

The center fin remains the dominant element of the setup: it defines the line, stability and overall behaviour of the board. The side bites complement this by adding grip when the board is on rail, allowing deeper engagement in turns.

The balance between these two elements is essential.

This guide focuses on two side bite sizes: 3.5” and 4”, the most common sizes covering all longboard and mid-length uses.

3.5” side bites remain discreet. They preserve a single-fin-like behaviour, with lots of glide, long lines and a very fluid board. In contrast, 4” side bites add more grip and responsiveness. The board becomes more dynamic, easier to turn and more modern in behaviour.

The fundamental rule remains simple:

The larger the side bites, the smaller the center fin should be.

And conversely, the smaller the side bites, the larger the center fin can be.

However, in practice there is an important limit: once the center fin exceeds 6.5”, only 3.5” side bites are recommended.

Why?

Because a large center fin already generates significant control and stability. Adding oversized side bites would unbalance the setup, making the board too stiff, less fluid and less enjoyable to surf.

Thus:

• a center fin of 7”, 7.5”, 8” works ideally with 3.5” side bites
• 4” side bites are reserved for smaller center fins, generally 6.5” or less, to add dynamism without excess.

When the center fin is large and side bites are small, the board behaves closer to a single fin: smooth glide, stable line and wider turns. This setup is ideal for semi-retro longboards, soft waves and noseriding.

Conversely, when the center fin is smaller and paired with 4” side bites, the board becomes more responsive. Rail-to-rail transitions are faster, turns are tighter and surfing feels more modern. This setup suits modern longboards, mid-lengths and faster waves.

Finally, note that total fin surface should increase as board size increases. 

2+1 setup examples by board type

The set consists of two side fins (right and left).

It comes with a fin key for installation.