What Are the Parts of A Baitcaster Reel? Brake Adjust Knob, Spool Release, Handle, & Other Functions

The modern baitcasting reel evolved from the Kentucky reels of the early 19th century when inventor William Shakespeare Jr. purchased the rights from another inventor, Walter Marhoff.

Marhoff’s addition was a level-wind mechanism that transformed Shakespeare’s earlier backlash-prone reel into the modern version of the baitcasting reel we all know so well.

Baitcasters are the second most popular reels after spinning reels and the favorite of bass fisherman across the world.

We’ll look at the construction of the baitcasting reel, describe the components and how the reel works, then jump into how to set up and successfully use one.

What Are The Parts Of A Baitcaster Reel Explained?

On the user side of a baitcasting reel, there are ten main components that allow anglers to adjust line tension, drag, and set individual reel settings.

These surface components hide the hundreds of intricate parts within the reel. 

Featuring complex gears, guides, and shafts, the baitcaster is one of the most popular reel types for freshwater species, such as bass and walleye.

The next step is to examine the main parts of a baitcaster reel. I will also provide images of my own gear for reference.

Here are the 10 most important parts of a baitcasting reel:

  • Spool
  • Brake adjust knob
  • Sideplate
  • Reel cage
  • Spool release button
  • Reel seat
  • Handle
  • Spool tensioner
  • Star Drag
  • Line Guide


The spool is the heart of any baitcasting reel. The size of the spool, combined with the gear ratio, determines the rate of retrieve per crank and sets the amount of line a reel can contain.

Those are perhaps the most important features when considering the size of reel you wish to purchase.

Spools are often made of lightweight, corrosive resistant aluminum or a salt and water-resistant metal alloy. 

Larger spools mean more line can be wound onto the reel. They also mean you can hold heavier pound test braided or monofilament line. 

The weight of the line is another important consideration when you’re selecting a reel for a specific application.

You wouldn’t want to try your hand at tarpon fishing with an ultralight reel, but you also wouldn’t want a heavy power rod coupled with a massive 80-pound test braid for catching bluegill either.

A quality spool should be smooth, roll effortlessly on well-designed ball bearings, and allow easy spooling out of line on casts.

Also Read: Smallest Baitcasting Reel

Brake Adjustment Knob

The main issue with baitcasting reels came a long time ago, all the way back to the 1820s and the advent of the Kentucky reel. 

Many people mistakenly claim that baitcasting reels are insufficient because of the issue of backlash.

There are two types of brakes on a modern baitcasting reel, either magnetic or centrifugal. Both are designed to prevent that dreaded backlash that used to ruin many fishing expeditions.

To prevent backlash, the angler can set the brake adjustment by turning a dial on the side of the reel body. 

It is one of the most experimented adjustments on a baitcasting reel and is not the same for every angler.


There are times when you need to access the inner workings of a baitcasting reel. Most often, this involves cleaning the inside of the reel. 

It is an especially good idea to clean the inner parts of a baitcasting reel after surfcasting or fishing from a boat on the ocean.

Salt buildup can create a lot of problems, even destroying a reel if left unchecked. 

The sideplate is the access point for the inside of a reel. Removing the sideplate is the first step in accessing the interior and it varies greatly between manufacturers. 

Sometimes it’s four small Phillips screws, sometimes Torx head bolts, and occasionally the older hex head style bolt.

Removing these and carefully taking off the sideplate is a process best completed on a table with a clean cloth placed under the reel to contain all the parts.

Reel cage

The reel cage has one function, to contain all the parts of a baitcasting reel. The sideplate anchors the access point for the reel, and the reel cage holds everything in place.

Reel cages contain hundreds of gears, ball bearings, and other moving parts of a baitcaster reel. 

They’ll also collect dirt, dust, sand, and salt crystals if the reel isn’t rinsed often in freshwater to remove this residue.

Reel Seat

It goes by a very plain name, and on the surface, doesn’t have the glamorous roles the other parts of a baitcasting reel does.

However, without it, you just have a stick and standalone reel with no function at all.

The reel seat is the interface that brings the two disparate components, the rod and the reel together, creating an angling machine right in your hands.

A tight reel seat that locks into the reel mounts on the rod is an integral part of the entire concept of a “fishing pole.”

Reel mounts have to fit seamlessly with the reel seat, or you won’t have a good experience out on the water.

Spool Release Button

Perhaps the greatest innovation in baitcasting reel design is a relatively recent addition, the spool release button.

Older spincasting reels required the angler to hold the spool with their thumb while whipping the rod to cast. 

Release of the thumb pressure allowed the spool to spin freely, sending the line out. And placing thumb pressure on the spinning spool slowed or stopped the cast.

It created many backlashes, knotting the line into snarls that took precious time on the water to untie.

The push-button releases the spool, allowing it to roll out the line easily. Only turning the handle re-engages the reel on most models.


The handle transfers the power source (your hand) to the reel mechanism. 

As the most active human interface on the reel, it is a must that the handle be comfortable in your hand, made of a durable material with a firm surface for gripping, and strong enough to battle the largest fish.

Spool Tensioner

This adjustable tensioning mechanism is the difference between a good reel and a great one when properly adjusted. 

Every angler casts a little differently than everyone else. By adjusting this tensioning dial, the reel can be matched perfectly with the person using it.

A properly tensioned reel won’t create backlash, is easier to control on casts, and can even produce longer casts once the angler becomes familiar with the right settings.

Star Drag

One of the greatest innovations in reel design sits just inside the handle on spincasting reels. 

The star drag is named for its obvious star shape, a shape similar to a spur on a pair of cowboy boots but one with a very different purpose.

Spinning reels and spincasting reels have drags, but most don’t have an “on the fly” drag adjustment like baitcasting reels do.

The star drag is easily adjusted with your thumb as you crank away trying to reel in a hard fighting fish.

With just a flick of the thumb, you can tighten up the drag, creating a small winch that can simply drag the fish to you via brute force.

A flick in the other direction, and your reel will spool out line with variable resistance that can tire the strongest fish, fighting in the heaviest current.

This innovation, when properly utilized, has landed more trophy fish than another angling invention.

Line Guide

Without this oscillating device, the line on a baitcasting reel would either pile up in the center, creating an obstruction for smooth casting.

Or it would have to be manually moved back and forth across the spool as it is retrieved.

The line guide moves back and forth like a sewing bobbin laying line neatly across the spool to ensure long smooth casts while remaining devoid of backlash.

The spiral grooves inside the bar the line guide moves on should contain plenty of quality ball and roller bearings.

The more the merrier when it comes to ball bearings inside a reel guide.

This is the part of a baitcasting reel that often fails first. It moves more than any other parts aside from the handle and must be kept free of debris, salt, and corrosion.

How Does A Baitcaster Reel Work?

Baitcasting reels differ from spinning reels, and spincasting reels, in the way their spools are oriented.

The two spin varieties spool line off the end of a vertical spool that is in line with the rod. A baitcaster spools the line out at a right angle to the rod.

This means the line rolls off a spinning spool on the cast and is cranked back onto the spool in a fashion similar to a winch.

This action allows more control in casting and a variable speed retrieve, a nice feature to have when pursuing top striking fish such as largemouth bass.

The spool on a baitcasting reel can be deeper, with a smaller center spindle, allowing for greater line capacity.

The horizontal layout of the spool allows greater flexibility in drag settings, both magnetic and mechanical line tensioning, and the ability to use the star drag spindle in the middle of a retrieve.

How Do You Set Up A Baitcasting Reel?

Setting up a baitcasting reel is a bait-specific procedure. On most reels, you’ll need to set the spool tensioner to match the weight of the bait you’re using before the initial cast. 

It is not nearly as difficult as it sounds.

To begin, attach the lure, drop shot rigging, or lead weight and hook to your line.

Find the spool tensioner knob on our reel and twist it all the way in until it is tight.

This will lock the spool in place when you press the spool release button.

Raise your rod tip about eight feet above the ground and press the spool release button. The bait should remain in place.

Slowly unscrew the spool tensioner until the bait slowly drops.

You want a little tension on the line. If your bait drops rapidly after pressing the button, you’ve released too much tension. 

The bait should gradually, a few inches per second, drop from the rod tip towards the ground.

When the rate of fall is slower, the risk of backlash is much less as well. With the setup complete, you should cast a long distance with no risk of tying up your line with a backlash.

Frequently Asked Questions

What Is the Knob on The Side of A Baitcaster?

The knob on the side of a baitcaster is the spool tensioner adjustment. It is the most important step in setting up a baitcasting reel.

As outlined above, the spool tensioner is your best defense against backlash during a cast. 

When correctly set, you’ll be able to toss your line as delicately or as powerfully as you wish without creating a bird’s nest of snarled line around the reel.

Why Are Baitcaster Handles on The Right Side?

Newsflash! That was true until relatively recently, but newer models now have handles available on both sides of the baitcasting reel.

The original design was created for right-handed anglers. 

If you were left-handed and wanted to use a baitcasting reel, you had to learn how to work the rod and reel with your right hand.

A baitcasting reel is more refined and finite in casting control than a spinning or spincast reel.  

Casting a baitcaster is a study in the art of fishing. You cast the line holding the rod handle in your right hand.

Switch hands while the line is in the air. 

Now holding the rod with your left hand, you can set the spool with your right and begin cranking in the line.

It was a natural process for a right-handed angler but difficult for left-handers to master. Modern manufactures have taken that into consideration with ambidextrous models.

What Does the Tension Knob Do on A Baitcaster?

The tension knob is protection against backlash. The knob located just behind the handle should be adjusted on most reels before casting with different weighted bait. 

Some recently released digital models make the initial baitcaster setup a one-time operation. 

Set the line tension with the tension knob, click the digital button, and the attached microprocessor sets the reel each time the bait weight changes.  

Some models don’t even require batteries. Instead, they’re charged each time you cast by a tiny generator attached to the spindle that recharges the interior battery.

What Are the Adjustments on A Baitcast Reel?

There are three adjustments you can make with a baitcasting reel. They are the line tension, the brakes, and the drag.

To set the line tension, follow the steps outlined above in conducting a reel setup. The line tension knob is near the handle.

There are two types of brakes, magnetic and friction. Setting a friction brake is an involved process requiring the reel sideplate to be removed and adjustments made inside the reel. 

That’s not done much anymore. 

Instead, an adjustment dial on the opposite side of the handle on most reels allows the magnetic brakes to be set with a simple twist of the dial.

The final adjustment is the one used most often is the star drag. 

You can set line drag while in a full retrieve with a fish on the line. The star drag is on the same shaft as the handle.

Why Do Bass Fishermen Use Baitcasters?

The simple reason that bass fisherman use baitcasters is for control. A baitcaster provides the control bass fishermen require for accurate casts in challenging conditions and other obstructions. 

The other control necessary for bass fishing is how fast a surface lure can cross the water.

Bass are aggressive but finicky. If a bait designed to look like a swimming mouse is too fast, they’ll ignore it. If one that is supposed to mimic a swimming frog moves unnaturally, they’ll ignore that too.

But, if the lure moves at a speed, and in a pattern the bass is attuned to, they’ll hit it like a freight train. 
That’s why bass fishermen prefer the baitcaster.

What Is the Button on A Baitcaster Called?

The button is called a spool release button, and it’s used to release the spool at the precise time during a cast. 

After a little practice, you’ll be able to time the pressing of the button with the whip of your rod, creating long, accurate casts.

Seel Also: Baitcaster Reel Sizes

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Sean Ward

Sean Ward

Hey there, my name is Sean – OnTrack Fishing is my site. I’m based in the UK yet I’ve been fortunate enough to catch bass in the States, barramundi in Australia, trout here at home and carp on the Danube delta. If I’m not fishing, or talking about fishing, then….I’m probably asleep.


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