What Are Fork Bleeders and Why You Need Them?

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Dirt bike front fork and the fork cap with fork bleeders installed

Front forks require regular oil changes and maintenance to keep them working well. Riding on different types of trails call for suspension clicker adjustments and fine-tuning the suspension to your liking.

One of the things many riders seem to neglect is to bleed the excessive air build-up inside the front forks. This air build-up can quickly affect the suspension performance as it slows down the front forks and can make the suspension feel harsh.

Fork bleeders are a game changer for quickly neutralizing excessive air pressure build-up inside the front forks. Fork bleeders are small hollow spring loaded air screws that replace the factory front fork air screws on top of the front fork caps. They enable a push button style quick release of the excessive air buildup inside the front forks.

Next, we will explain how these fork bleeders work, how to install them, and what are the benefits of using quick air bleeders.

Front Fork Air Reservoir in a Nutshell

Front fork suspension components work in parallel with the fork oil moving around inside the fork leg and the air chamber reservoir. The air inside the fork leg is an important suspension element. When you ride and even when the dirt bike is stationary, the amount of air pressure inside the front forks is changing for various reasons.

Front fork designs are typically open chambered or closed chambered, and the main difference in these designs is the air reservoir design. The open chambered forks have zero pressure air reservoir whereas the closed chambered forks have an adjustable high pressure chamber pushing against the oil.

The air inside the fork is temperature sensitive. Air expands in hotter environments and contracts in colder temperatures. These changes related to the ambient temperature affect the air pressure inside the fork.

While riding, the suspension oil and internal components will heat up. This heat dissipates also into the air, thus further expanding the air and adding more back pressure.

Small leaks, dirt, and debris in the dust and oil seals also typically add air inside the fork legs, usually during the compression cycle pushing some air inside the forks. This also adds to the overall air pressure build-up in open chambered forks.

Read also: How To Set Up Dirt Bike Suspension For Trail Riding

How Air Pressure Affects Suspension Performance

The air inside the fork leg works parallel with the fork oil. The open chamber fork design has typically about 4 inches of air on top of the oil level and the fork cap. When the fork compresses the air is also compressed inside the fork. This air pressure affects the compression and rebounding speed of the fork leg.

Dirt bike front fork leg on the table next to fork bleeders

The excessive air inside the forks can usually feel like the plushness is gone and the riding starts to feel harsh. This is usually an indication to bleed the forks for excessive air build-up.

Read also: How To Align Dirt Bike Forks – aka Twisted Forks

How To Adjust or Release Front Fork Air Pressure

If your forks are open chambered, the manual instructs to open the small screws on top of the fork caps. This should be done prior to every ride day to balance out the amount of air in each fork leg. The small screw has a rubber o-ring seal and can be under quite a lot of pressure, so be careful not to let the screw fly away when opening.

When you open the air bleeder screw slowly, you should hear the excessive air escaping from the fork leg. After the air pressure is stabilized, tighten the screw back in. You don’t have to fully remove the air screw, since the air is able to escape through the threads with an audible hiss.

In a closed air fork designs, you can adjust the air pressure inside the fork leg by using a fork pump. There are no air bleeder screws to worry about. However, the same principles apply. Check the air pressure frequently as it does change based on outside temperature. Refer to your owners manual for detailed instructions.

Front Fork Air
Motion Pro Micro Fork Bleeders - WP KTM
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Works Connection Digital Fork/Shock Pump
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Fork Bleeders Help Bleed Excessive Air Quickly

Sometimes called as speed bleeders, the fork air bleeders make bleeding the fork forks very easy.

Usually, the speed bleeders work with a push button style quick air release valve that can bleed the forks in seconds.

Front fork leg upright ready for air bleeder installation

After installation, you simply press the top of the speed bleeder to release any excessive air in open chambered forks to reset the air pressure to the surrounding ambient pressure. This guarantees normal fork performance and also prevents from front fork oil leaks.

Read also: How To Clean Leaking Fork Seals On a Dirt Bike

How To Install Front Fork Bleeders

Installing the fork bleeders is a quick 10-minute task. Remove the factory bleed screws and install the fork bleeders in place.

Greasing air screw o-ring with grease to ease installation

Do not over tighten the bleeders as they have an o-ring for proper seal. You can also lube the o-ring slightly to prevent damaging the seal.

When To Bleed Air From Front Forks

These are the typical situations when speed bleeders come in handy and should be used:

  • After strapping the dirt bike down for transportation. Strapping the front down increases the fork air pressure and can cause oil seals to leak during transportation.
  • After transportation. Once you release the front forks, reset the air pressure inside the forks.
  • Elevation changes can cause low or high pressure difference inside the fork. Bleed often when riding at high elevation changes.
  • Temperature changes. Bleed before you ride.

Fork Bleeders Can Help Prevent Leaky Forks

Releasing the excessive air build-up inside the forks is a great way to prolong the oil seal life in the front forks. The excessive air pressure can push out the oil and quickly cause the oil leaks. This usually happens when there is already some dirt inside the dust seal and it’s traveling under the oil seals.

Cleaning the fork oil seals with a seal bullet or similar tool will help and usually stop minor dirt related leaks. If the leaks quickly come back, inspect and replace the fork oil seals during the next oil maintenance cycle.

Make sure to check out our complete instructions for how to change fork oil on open chambered forks. It also covers how to change the oil seals.

Conclusions

Fork bleeders are a must for any open chambered forks. The quick air release will help prevent fork oil leaks and keep the forks running at optimal performance levels.

Fork bleeders are simple to install and easy to use and are likely one of the best small upgrades every rider should install on their dirt bike.

Keep airing out those forks!

Last updated: June 27, 2022