Why Put Backing Line on a Spinning Reel?

  • Date: August 14, 2022

You’ve just bought a brand new spinning reel, and you’re just about to spool it with line.

But wait! You’ve just read that you need to add backing line onto your spool as well? 

Why do you need backing line? What is backing line? How do I put it on my spinning reel?

All these questions and more, are answered in this article. Read on…

What is backing line?

Backing line is used to wind onto your spool first before you add your main line.

You will attach the backing line to the spool (usually with an arbor knot), then tie a knot from the backing line to your main line, and then start winding the main line onto your spool.

Why do you need backing on a spinning reel?

There are a couple of important reasons why you need to add backing line to your spinning reel before you add your main line.

The first reason is to stop your main line from slipping on the spool.

A lot of spools have a shiny surface, and if you are using either braid or fluorocarbon as your main line, then this can slip around the spool when under tension.

what do you need backing line on a spinning reel

If your main line starts slipping around the spool you will have no control of the fish you are fighting, and you will lose more fish than you land. It can also cause tangles in your line as well.

I should mention that you will find some spinning reels where the spools are now ‘braid ready’.

These spools tend to have a band of rubber that encompasses the spool and will allow you to tie your braid (or fluoro) line directly to the spool arbor without using backing line.

But even if you have a braid-ready spool, I still prefer to add backing line, for the reason mentioned below.

The second main reason to use backing line is to ensure you get enough line onto your spool.

Ideally, when you add some new line to your spinning reel, you will want to fill the spool up until you have a 1/8-1/16 inch gap from the lip of the spool to ensure optimal performance and casting distance.

But if you have just purchased 150 yards of braid to use as your main line, and your spool capacity is 185 yards, you are going to have quite a deficit and a large gap from the lip of your spool once all of 150 yards of braid has been added.

Ensure you get enough line on your reel by using backing line

One option would be to buy 300 yards of braid to add to your spool, but in the example used above, you would be left with around 115 yards of expensive braid once you have fully spooled your reel.

What do you do with that? It’s basically surplus and you will spend quite a bit of money buying the 300 yards when a lot of it will not be used.

So, the option here is to use backing line. That way you can purchase the 150 yards of braided line, add a sufficient amount of backing line and then add the 150 yards of braid so that it sits nicely with just a very small gap from the lip of the spool once it has all been wound onto the reel.

Doing this will save you a lot of money over time, and also enable you to fill your reel with the optimal amount of line for the best performance.

What type of line to use for backing

The most commonly used line for backing is just a normal monofilament line. I personally only ever use mono for backing, it does the job perfectly and it is not as expensive to buy as other types of fishing line.

I usually buy spools of cheaper monofilament of various strengths that I use specifically for backing line.

mono for backing line

The reality is that you very rarely have a situation where your reel is stripped down to the backing line, so you just need it there to serve the two jobs it does as mentioned above.

Do you need backing when using braided main line?

As mentioned before, you can purchase spinning reels that come with ‘braid-ready’ spools, which have a strip of rubber around the arbor of the spool that provides some grip for the braid line if you did want to fill your spool with braid only.

But I do not recommend you use braid all the way through, I would always add a layer of standard monofilament backer to bulk out the line a bit on the spool and it just makes a more economical way of spooling your reel.

What size mono to use as backing

There is no set rule as to what size mono you should use for your backing line, but you should always keep it fairly close to the pound test you will use for the main line.

When using braid main line, I usually prefer to go just a little heavier with the mono backer. For example, if I am using 8-pound braid main line, I will go with 10-pound mono as the backer.

I have one of my reels spooled with 20-pound braid and I am also using a 20-pound mono backer, as I didn’t want to go up to a 30-pound mono backing line.

Calculate how much backing line you should use

One of the main reasons for using backing line is to allow you to fill your spool up to the optimal level, without having to buy excess amounts of braided main line, which can get very expensive.

The way I work out just how much backing line to use is as follows:

1. Understand what the line capacity is for the reel you want to add the line too. You can do this by going to the manufacturer’s page, check the size reel you have and the capacity for the pound-test braid line you want to add.

2. If you can see the capacity for braided line on your reel is 185 yards, you can purchase 150 yards of braid to use as your main line. You will then need to make up the difference with your mono backer.

3. Work out how many inches of line your reel winds per one crank of the handle. Again, you can find this information on the manufacturer’s page for the reel you have.

Example: Let’s use the Shimano Vanford reel for this example. Let’s say you have the 3000-size reel and you want to spool it with 10-pound braid. Go to the manufacturer’s page for this reel, and check the line capacity for 10-pound line, and the retrieve rate per crank.

If you have 150 yards of 10-pound braid, and you know the capacity of your reel is 200 yards, you know you need to add around 50 yards of mono backer.

4. Next make a calculation. There are 36 inches in 1 yard, and we need 50 yards of backing line – 50 x 36 = 1,800 inches of backing line required.

From the manufacturer’s specs’, this reel retrieves 37 inches of line per crank. So we divide the total number of inches of backing required by the number of cranks – 1,800 / 37 =  48.64.

So you now know you’ll need around 48 cranks of the handle to wind 50 yards of mono backing line onto your spool.

How to put backing line on a spinning reel

Adding backing line to your fishing reel is an easy process:

As you would with your main line, it is ideal to ensure you wind the backer line on with the spool under tension to ensure the line is tightly packed onto the spool.

1. Secure your reel to your rod, and feed the backing line through the bottom rod guide.

2. Make sure the bail arm on your reel is open. Tie the end of the line around the spool. The best knot to use for this is an Arbor knot.

3. Once you have tied and tightened the Arbor knot around the spool, cut the tag end off and then add a small bit of tape over the knot.

4. Close the bail arm on the reel, ensure there is some tension on the line and start winding the backing line onto the reel.

5. Count each turn of the handle to measure accurately how much backing line you are adding to the reel. Using the example I detailed above, you would need to turn the handle 48 times to wind 50 yards of backing line onto the reel.

That is the process for adding the backing line onto your reel. Once you have done this, you now need to attach the backing line to your main line.

I always use a double uni knot to do this. It is fairly low profile and has an excellent breaking strength should you ever need that.

Be sure to cut the tag ends away as close as you can to the knot as you don’t want those protruding with more line laying on top of it.

Can you use fluorocarbon as backing?

If you don’t have any cheap monofilament available to use for backing, then it is possible to use fluorocarbon lines as a backer.

It will do the same job as mono and will prevent your braid main line from slipping on the spool. But it is an expensive option, and for this reason alone it is more economical for you to use a cheap mono line for this job.

Should you use backing line if using fluorocarbon main line?

If you want to spool your reel with fluorocarbon as your main line you would not need to add any backing line to prevent slipping on the spool, and fluoro will grasp hold of the spool well.

The only time you would consider using mono backing line with fluoro main line is if you don’t have enough fluoro to optimally fill your reel up. 

If this is the case you would just need to run the same equation as mentioned above and add the required amount of mono backer.

How much backing line should a spinning reel have?

There is no set amount of backing line you should use.

The main two aspects you need to cover are having a sufficient layer of mono backing line to ensure your braid main line doesn’t slip, and also having enough backing line to ensure you load your reel up to the optimal level with your braid main line.

If your reel capacity is for 150 yards of line, and you have 150 yards of braid main line to add, then you would just need to add a light layer of mono backer, just ensure that all of the spool arbor is covered with the backing line before you start adding the braid main line onto the spool.

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