Backing is the braided line attached directly to the fly reel before the fly line is fitted.
For many anglers, backing spends its entire life hidden beneath the fly line, leading some to question whether it is really necessary. In reality, backing performs two important jobs. It provides additional line capacity for powerful fish, and it increases the effective diameter of the reel spool so the fly line sits correctly on the arbor.
How much backing you need depends entirely on the type of fishing you do.
For many trout anglers, the backing may never leave the reel. For salmon and powerful saltwater species, however, backing often becomes an essential part of the outfit.
## What Does Backing Do?
Backing has two main purposes.
Firstly, it provides extra line when a fish takes longer runs than the fly line alone can accommodate.
Secondly, it fills the reel spool beneath the fly line.
Without sufficient backing, the fly line would sit very close to the arbor, reducing retrieval speed and making the reel feel less efficient.
Even if you never expect to see the backing, the reel should still be filled correctly.
## What is Backing Made From?
Most fly backing is manufactured from braided Dacron polyester.
Dacron is:
* Strong.
* Flexible.
* Resistant to rot.
* Easy to knot.
* Long lasting.
For larger salmon and saltwater fishing, some anglers choose gel-spun backing.
This has a much smaller diameter for the same breaking strain, allowing considerably more backing to be loaded onto the reel.
## How Much Backing Do Trout Anglers Need?
Usually, not very much.
River trout and grayling rarely run far enough to expose the backing.
Even on reservoirs, many trout are landed without ever leaving the fly line.
Most manufacturers recommend enough backing to correctly fill the reel once the fly line has been fitted.
That is normally all that is required.
## Reservoir Trout
Although most reservoir trout never reach the backing, there are occasions when powerful fish take long runs, particularly when hooked close to the boat or from the bank in open water.
For this reason, reservoir reels are normally loaded with enough backing to both fill the spool correctly and provide a sensible reserve should a larger fish run further than expected.
## Salmon Fishing
Backing becomes much more important when targeting salmon.
Powerful fish can make long downstream runs that quickly take anglers well into their backing.
The amount required depends on:
* River size.
* Reel capacity.
* Fly line system.
* Manufacturer's recommendations.
Modern salmon reels are designed to accommodate both the intended fly line and an appropriate amount of backing.
## Saltwater Fishing
Backing is absolutely essential for many forms of saltwater fly fishing.
Species such as:
* Bonefish.
* Permit.
* Tarpon.
* Giant trevally.
* Tuna species.
can remove large amounts of line in a matter of seconds.
Running out of backing almost always results in losing the fish.
For these species, backing capacity is often one of the most important considerations when selecting a reel.
## What Breaking Strain Should I Use?
There is no single correct answer.
Generally:
### Trout
* Around 20 lb backing.
### Salmon
* Around 30 lb backing.
### Saltwater
* 30 lb or higher depending on the species.
Always ensure the backing strength is appropriate for both the species being targeted and the reel capacity.
## Can I Put Too Much Backing on a Reel?
Yes.
If too much backing is fitted, there may not be enough room for the fly line.
Overfilling the spool can cause the fly line to rub against the reel frame and create unnecessary tangles.
The finished fly line should normally sit just below the rim of the spool, leaving a small clearance around the outside.
## Can I Have Too Little Backing?
Yes.
Too little backing leaves the fly line sitting close to the arbor.
This reduces retrieval speed and can make the reel feel less efficient.
It also leaves very little reserve if a fish takes an unexpectedly long run.
## Does Backing Wear Out?
Backing lasts a long time.
However, it should occasionally be inspected for:
* Abrasion.
* Discolouration.
* Fraying.
* Damage caused by saltwater.
If the backing becomes damaged, replace it before it fails under pressure.
## Do I Need Gel-Spun Backing?
For most UK trout fishing, no.
Traditional Dacron backing is more than adequate.
Gel-spun backing is mainly used where maximum capacity is required, particularly on smaller reels targeting large, powerful fish.
It allows considerably more backing to be loaded onto the spool because of its smaller diameter.
## Which Backing Should I Choose?
### River Trout and Grayling
* Around 20 lb Dacron.
* Enough to correctly fill the reel.
### Reservoir Trout
* Around 20 lb Dacron.
* Enough to fill the reel and provide a sensible reserve.
### Salmon
* Around 30 lb backing.
* Capacity based on the manufacturer's recommendation.
### Saltwater
* Dacron or gel-spun backing.
* Breaking strain and capacity matched to the target species.
## Related Articles
* Choosing a Fly Reel.
* Fly Reel Drag Systems.
* Large Arbor vs Standard Arbor Fly Reels.
* Fly Reel Maintenance.
* Fly Lines Explained.
## Peaks Fly Fishing Tips
* Backing isn't only there for running fish - it also helps fill the reel correctly.
* Most trout anglers rarely see their backing, but it's still an important part of the outfit.
* Never overfill the reel, as this can cause line management problems.
* Always follow the reel manufacturer's recommended backing capacity.
* For salmon and saltwater fishing, backing capacity can be just as important as the drag system.
