Your board has side bite boxes. You have side bites in a drawer somewhere. The question everyone asks and nobody answers clearly: should you put them in?

Here's the actual answer.

What Side Bites Do

What are side bite fins?

Side bites are the two small fins that sit near the rails, forward of the center fin, on a board set up as a 2+1. They run from 2.6" to 4.35" tall, in FCS and Futures. The center fin still steers; the side bites add hold and drive when the board is on rail.

What do side bite fins do on a longboard?

A single fin generates all its hold and drive from one point. When you turn, you load the fin, it flexes, and releases. The whole board pivots around that one fin.

Side bites add two more contact points near the rails. When you put the board on rail, the side bite on that side engages the water and pushes back. More hold. More drive through the turn. Less slide. On a longboard, that's a tail that holds its line on a steep drop or a hard bottom turn instead of sliding out.

That's it. They're not magic. They add grip when the board is on rail.

What They Don't Do

They don't make your board faster. They add drag—two more fins in the water is two more sources of resistance. On a clean, open face where you're trimming, side bites slow you down.

You'll also read the opposite: that a 2+1 is faster because its center fin is smaller. Both pulls are real. The smaller center sheds a little drag and the two side bites add some back, and nobody publishes a drag figure for either setup. Which wins depends on the board and the wave. Ride it both ways on the same day and you'll know.

They don't make your board easier to turn. They do the opposite. More fins gripping the water means more resistance to direction changes. Your board becomes stiffer through transitions. They do let you turn harder, though, because the side bites hold the rail while you push. Harder turns, yes. Easier turns, no.

They don't fix a bad fin setup. If your center fin is wrong for your board, adding side bites just adds more wrong.

When to Put Them In

Is a single fin or a 2+1 better on a longboard?

It depends on the wave and how you surf it. A single fin is better for trim, glide and noseriding in small, clean waves. A 2+1 is better when the wave is steep, when you turn hard off the tail, or when the tail slides out on a single. A board with a long center box and two side plugs does both: put the side bites in when the surf calls for them, take them out when it doesn't.

Your wave is steep and you're losing hold. This is the original reason side bites exist. When the wave gets steep, a single fin can lose grip—the tail slides, you lose your line, you eat it on the drop. Side bites give you rail-to-rail stability in steeper surf. If you're surfing overhead waves on a mid-length and the tail keeps washing out on your bottom turn, try side bites before you try a bigger center fin.

You want to surf your longboard more aggressively. If you're doing performance longboarding—real turns off the tail, not just trimming and noserides—a 2+1 setup lets you push harder into turns without the tail releasing. The side bites catch you when you'd otherwise slide out. This is why the 2+1 is the standard setup in performance longboarding.

Your board was designed for it. Some boards are shaped specifically for a 2+1 setup: more rocker, harder rails at the tail, concave through the bottom. The shaper built the board expecting three fins to be in the water. Running it as a single fin will feel loose and underpowered because the board's outline was designed to work with side bites.

Your shortboard or paddle board has side plugs. It isn't only a longboard setup. Plenty of shortboards and paddle boards come with a center box and two side plugs. On a shorter board, both the center fin and the side bites run smaller (see "The 2+1 Setup" below).

When to Leave Them Out

You're noseriding. Side bites add drag at the tail, which changes the balance point of the board. For dedicated noseriding on a classic log, a single fin keeps the tail clean and lets you walk to the nose without fighting extra resistance behind you. The whole point of a good noserider single fin (big pivot fin, lots of area) is that it holds the tail down so the nose lifts. Side bites mess with that equation.

You're on a classic log or hull. These boards are designed around the single fin. The smooth, flowing, drawn-out turn of a log comes from loading one fin and releasing. Adding side bites stiffens the turn, shortens the arc, and kills the glide. A hull is even more specific—the bottom contour channels water into the center fin. Side bites disrupt that flow.

You want speed on a clean face. If you're surfing small, clean waves and the goal is trim speed and flow, every extra fin is drag you don't need. One fin, less resistance, more glide. This is physics, not opinion.

You're still learning to trim. Side bites get called training wheels, but they only work on rail, and while you're learning you spend most of the ride flat. There they add drag and little else. Put them in once you're turning off the bottom and feeling the tail slide.

You can't feel the difference. This is the honest one. If you've been surfing with and without side bites and you genuinely can't tell, leave them out. Less drag, simpler setup, nothing to lose. The people who benefit from side bites know immediately because the hold difference is obvious. If it's not obvious, you don't need them.

The 2+1 Setup: Getting the Sizes Right

What is a 2+1 fin setup?

A 2+1 is a single fin in a long center box plus two small side bites in plugs near the rails. Think of it as a single fin with help: it keeps the smooth feel and adds drive and hold.

John Perry and Dave Lamberston are credited with creating it. They called it the "Threedom," and Perry's Performer came out of that work as a center fin meant to run with side bites. Performance longboarders took it up in the 1990s and early 2000s.

Don't confuse it with two neighbors. A thruster runs three fins of about the same size and template. A twin + trailer flips the 2+1: two big fins and a small center trailer.

This is where most people get it wrong. You can't just throw your 9" single fin in the center box and add side bites. That's too much total fin area—the board will track like a train and refuse to turn.

The sizing approach is straightforward. A 2+1 is a single fin with side bites added, and three rules do most of the work:

Drop the center fin. In a 2+1 the center runs smaller than the single fin you'd ride alone, because the side bites add area.
Trade center against sides. The bigger the center fin, the smaller the side bites can be. Go up in side bites and you can come down in the center.
Bigger board, more total fin area.

Typical setups: shortboards run a 5.5"–6.5" center with 2.6"–3.7" side bites; mid-lengths and eggs a 6.5"–8" center with 2.6"–4" side bites (the mid-length fin guide goes deeper); performance longboards a 6.5"–8" center with 3.25"–4" side bites.

A single fin runs about an inch of height per foot of board, so a 9' board takes a 9" single, something like the Greenough 4A in 9". As a 2+1, drop to a 7"–7.5" center with 3.7" or 3.25" side bites; a 7" center with 3.25" sides is a common combo. An 8' board takes a 7.5"–8" single; as a 2+1, a 6.5"–7" center with 3.25" or 2.6" side bites.

The exception is a very light pair like the Lovelace Side Runners: keep the center fin you'd usually ride, or go a touch smaller.

The center fin template matters too. A cutaway fin like the Cutaway (narrow base, less area) is designed to work as a 2+1 center, usually at 7", 7.5" or 8". The Wayne Rich Power Tilt is the other one to start with: a medium-area template that works in a 2+1 in all conditions, and the center the Wayne Rich side bites are drawn to match. A big pivot fin is designed to work alone. Don't put a 7" pivot fin in a 2+1—the base is too wide relative to the side bites and the board will fight itself.

Can you run side bites without a center fin?

Yes, as an experiment. Take the center fin out and the board rides close to finless: loose, quick to spin, with little hold off the bottom. It's a good way to feel how much work the center fin was doing. The Skip Frye side bites are made for trying it (see "Side Bites by Template"). Put the center fin back once the waves have any push.

Side Bite Sizing

What size side bite fins?

Side bites run from 2.6" to 4.35" tall, and the 3.7" is where to start on a 2+1. Go smaller to keep more of the single fin's feel; go bigger for steeper waves, bigger boards and heavier surfers. Whatever size you pick, size the center fin to match: the bigger the side bites, the smaller the center.

Height is the number you feel. Taller side bites grip the rail harder and drive more off the bottom turn; shorter ones leave more of the single fin's loose, pivoty feel. Area climbs faster than height: the 3.7" has more than twice the area of the 2.6" (10.25 sq in against 4.51). Size the center fin to match (see above).

The standard side bites come in five heights, FCS and Futures, in solid fiberglass or hexcore:

2.6" (2.25" base, 4.51 sq in, flat foil). Barely there: a safety net for a single fin, or a twin that gets loose once the surf has size. Also the fix when a board's side bites feel too big. The FCS pair has a single tab, so each fin can go in the front or back plug.
3.25" (3.38" base, 8.38 sq in). The light end of a real 2+1. Adds hold without taking much of a log's looseness away; with a 7" center it's the common combo.
3.7" (3.63" base, 10.25 sq in). The size we recommend most often, and where to start. Noticeably more hold and drive than the 3.25", still short of locking the tail.
4.0" (3.9" base, 11.73 sq in). Performance longboards and mid-lengths in steeper waves: stability and projection when the board is on rail.
4.35" (4.38" base, 14.75 sq in). The most side fin. Here the side bites stop being a subtle addition and start shaping the turn. Longboards and mid-lengths surfed off the rail in surf with some size; if you want a single fin with a safety net, go smaller.

Side Bites by Template

Past height, the outline sets the feel. A long, low base drives and holds a line; a shorter, upright fin with a thin tip lets go more easily. Some templates are drawn small on purpose so the center fin keeps doing the work.

Skip Frye side bites

2.75" and 3.0", FCS and Futures. Stubby: a 3.70" base, wider than the fin is tall, so the area sits low (7.38 and 7.91 sq in). For a single fin that's nearly right and needs just a little extra bite. The 3.0" is the one you'll notice. Or try the pair on its own, center box empty, and see what the board does close to finless.

Brothers Marshall side bites

2.64" on a 2.54" base, 5.14 sq in: small and nearly square. FCS and Futures. For a mid-length or longboard that already works as a single fin and only needs holding together when the surf has some push. If you want the sides projecting you out of the bottom turn, go taller and longer-based.

Lovelace side bites

3.46" on a 3.01" base, 8.02 sq in, 5° cant, flat inside foil, Futures. Ryan Lovelace drew them for a slightly more parallel 2+1 or a deliberately under-finned one, set clustered rather than spread like a classic performance 2+1. The center fin keeps the board's feel; these add a little bite behind it. Longer boards and minigliders, and the smaller option for a board that felt over-finned with a full-size set.

Wayne Rich side bites

3.4" and 4.0", FCS and Futures. Slightly more upright than the standard side bites, with a thinner tip and more relief through the trailing edge. Drawn for the Wayne Rich Power Tilt center fin, but they work with plenty of others. The 3.4" (8.66 sq in) suits smaller riders, smaller boards, or a subtler addition; the 4.0" (11.04 sq in) suits average to larger riders, bigger boards and bigger waves.

Tyler Warren side bites

3.25" on a 3.29" base, 8.60 sq in, Futures, in honey or black. The same height as the standard 3.25", with a slightly shorter base and a little more area, and a moderate rake. That puts them at the light end of a real 2+1: more hold through a turn, while the center fin still decides how the board rides. For a single fin or a 2+1 longboard or mid-length that should hold a line and keep its trim.

Channel Islands (CI) side bites

A 3.6" pair for FCS, and the CI Mid 2+1 combo: a 6.5" center with 3.6" or 4.0" side bites, developed with Channel Islands and Devon Howard for mid-lengths. The 6.5" with the 4.0" sides is the standard pairing; take the 3.6" if you're lighter or want the tail looser.

Bonzer-style side bites

The Lovelace Side Runners are a small, steep pair: 1.98" deep on a 3.95" base, 6.36 sq in a side, FCS, with 15° of cant built into the tabs. Ryan Lovelace draws them for hulls, mid-lengths and eggs, with obvious roots in the Bonzer. They're a light addition, so keep the center fin you'd usually ride, or go a touch smaller, rather than stepping down the way you would for bigger side bites. Canted that far out, they hold when the board is on rail and stay out of the way when it isn't.

What are the best side bites?

The best side bites are the ones that suit the board and the wave. Start here:

Keep the single fin a single, with a safety net: the 2.6", Brothers Marshall or Skip Frye.
A standard 2+1 on a mid-length or longboard: start with the 3.7"; drop to the 3.25" or the Tyler Warren for a looser ride.
The center fin does the work, the sides add a little bite: the Lovelace side bites.
Performance longboard, steeper waves, bigger surfer: the 4.0", the Wayne Rich 4.0", or the CI Mid with its 4.0" sides.
The most hold and drive on a longboard or mid-length: the 4.35".
Bonzer-style hold on a hull, mid-length or egg: the Lovelace Side Runners.

Construction, Foil and Fin Boxes

Solid fiberglass or hexcore?

The standard side bites come in both from 3.25" to 4.35"; the 2.6" and every other template are solid fiberglass. Solid fiberglass is the stiffer, heavier of the two: less flex, more direct drive. Hexcore, a honeycomb core and fiberglass laid up in a mold with resin pulled through, is lighter and flexes more, so it feels livelier and springier. More flex reads as looser, with a slightly delayed response and often more projection out of a turn. Stiffer reads as controlled and quick to respond.

Foil and cant

Side fins usually run a flat inside face and a curved outside; the 2.6", the 4.0" and the Lovelace side bites are cut that way. Center fins run a symmetrical 50/50 foil. Cant is how far a fin leans out toward the rail. Futures fins generally carry their cant in the fin; most FCS fins carry none, and the plug sets the angle. The FCS exceptions lean on purpose: the Bonzer runners (19°) and the Lovelace Side Runners (15°), with the cant built into the tabs. No cant is fastest in a straight line, some cant adds control in turns, and more cant adds lift and drag.

Do FCS side bites fit FCS II boxes?

Yes. FCS side bites use the traditional two-tab base, which fits both classic FCS plugs and FCS II boxes. Futures is a different system, one long base held by a grub screw, so Futures fins and FCS plugs don't mix. Check your plugs before you buy.

One more catch: Futures side bites have a 3/4"-deep base, so they won't fit the shallower 1/2" boxes used for rear quad fins.

Fin Cluster Spacing

Where should the center fin go in a 2+1?

Start with it in the middle of the box. If the tail slips on bottom turns, slide it back. If the board feels stiff and hard to turn, slide it forward. Move it a quarter to half an inch at a time, and change one thing per session.

On a 2+1, the side plugs are fixed where the shaper put them. What you move is the center fin, and that changes the spacing of the whole cluster:

Closer together (center fin forward): Faster turns, more responsive, board pivots quicker. Feels more like a shortboard thruster. Good for performance longboarding.

Further apart (center fin back): More stability, wider turning arc, board holds its line better. Feels more like a single fin with extra hold. Good for bigger surf where you want hold without twitchiness.

Box position of center fin: Same rules as a single fin. Forward = looser, back = more hold. With side bites in, you can usually push the center fin a little further forward than you would as a single, because the side bites provide the hold you're giving up.

The one exception to fixed side bites is the 2.6" for FCS: it has a single tab, so it can sit in the front or the back of the plug.

Canards and Other Small Fins

Canards: Small front fins used in a Twinzer setup, set just forward of the twins and out toward the rail. They break the water tension ahead of the larger rear fins, which generate the lift and drive. Canards here come from Lovelace, Lovelace FM, Derrick Disney RDM, Derrick Disney DST, Mandala, Pavel, True Ames, and Valaric. A Twinzer gets a bit more bite than a twin and drive like a quad. Some canards are drawn for a particular twinzer rear fin (Lovelace, Lovelace FM, Mandala), but they work in other combinations too. The twinzer guide goes deeper, including how plug angle and canard angle add up.

Bonzer runners: The Bonzer is the Campbell brothers' system: a center fin plus heavily canted runners that work with the board's bottom contours. The Bonzer Runners (4) are the side fins for a five-fin Bonzer: two 2.37" fronts and two 2.75" backs, all with 19° of cant built in above the tabs, so they go straight into FCS plugs with nothing to angle. Run them with a Bonzer center fin, not a thruster set. The Bonzer fin guide sizes the whole system.

The Call

Put in the side bites if: steep waves, performance longboarding, your board was shaped for 2+1, you want more hold and drive and are willing to trade speed and flow.

Leave them in the drawer if: you're noseriding, riding a classic log or hull, surfing clean small waves, still learning to trim, or you honestly can't feel the difference.

If you're not sure: try them for a few sessions with a smaller center fin, then take them out. The difference is immediate. You'll know which you prefer within one wave.

We stock side bites from True Ames for FCS and Futures, 2.6" to 4.35", in the templates above. Come by the shop and we'll match them to your center fin and board.