The front suspension fork, a staple of mountain bike pioneering. Hardtail mountain bikes and full suspension bikes owe a huge part of their capabilities to the front mtb suspension forks featured on this type of bicycle. Suspension forks have come light years from their release in the decades ago, with a focus on higher performance, longer life, and lower weight. While these modern marvels of mountain biking are made of many parts and pieces, the two main components responsible for this invention's success are the spring and damper.
Coil Spring
The spring allows the suspension to move up when the wheel engages with bumps or obstacles, and in turn allows the quick downward movement after the wheel passes the obstacle. The design of the spring has evolved from a steel coil spring to an empty chamber filled with pressurized air, both designs are still used today and have their benefits in specific riding applications. The ability of the spring to compress, but not bottom out is what determines what style of riding a specific fork design is suited for. You don't want a coil or air shock bottoming out when you land after a big air.
Damper
The Damper is what regulates the spring, and keeps it from bouncing up and down continuously after impact. When the spring is compressed, the entire suspension system must dissipate that energy and the damper is the component that achieves this feat, as well as allows for finer tuning of most forks. Most dampers are filled with oil similar to the design of a car suspension system. The shock absorber compressed, in this moment a piston forces oil to pass through a small hole which requires a lot of force. Energy is pushed through this small hole, causing the oil to heat up. This also dissipates energy and applies resistance to the shock compression. The faster you compress the shock while riding, the more oil has to be pushed through that small hole, creating pressure. This is what creates stiffness in the front fork. A balance between the spring compression and the dampening is the ultimate goal, and this balance is different for each rider and riding style. Air springs are typically more adjustable that coil, however coil has benefits such as heat dissipation that still make it a viable choice for a lot of extreme athletes and average joes.
Now that we have a better idea of what goes into the design and performance of a front suspension fork, what can we do to keep our suspension fork running at its best? Maintenance, maintenance, maintenance! Suspension manufacturers have a recommended service schedule for all of their products, and highly recommend adhering to this schedule if you want your suspension to feel plush and last a long time. If you've ever hopped on an old bike and felt the suspension fork feel sticky or sluggish, the fork is most likely overdue for service. From wiping down your stanchions with a microfiber towel, to replacing the seals there is a lot that can be done to help keep your fork operating in optimal condition. Ultimately a fork deserves a full break town of the damper and air spring assembly, when exactly depends on the service interval determined by the manufacturer.
Fox
Fox recommends a minimum suspension fork service after 125 hours of riding, or once a year, whichever comes first. While this is their minimum recommendation, many riders prefer to service the front fork twice a year as this practice provides a better performing fork and a longer overall life. As with any recommended service one should take into account all factors playing into the wear and tear on your front fork. Riding terrain that is heavy in dust, mud, or debris will increase the opportunity for debris to enter your fork internals and contaminating your oil. If you put your front fork through a lot of abuse, do it a favor and service it more often to ensure it has your back when the trail gets rough, for years to come.
Fox recommends that the minimum suspension fork and shock service is every 125 hours of use, yearly, or whichever comes first. That is certainly on the longer side of things. The more frequently you service your suspension, the better the fork will perform for longer.
RockShox
RockShox recommends servicing your suspension fork more often than their competitor, in general every 50 hours of ride time. Changing the oil, cleaning or replacing seals, and replacing foam rings are the common practices for a lower leg service. Sticking to a maintenance schedule will keep your fork running smoothly and make your rides more enjoyable.
Suspension Care & Maintenance
Do I need to lubricate the stanchions on my fork, rear shock, or dropper post?
Most suspension and dropper post systems are designed to be self lubricating and do not require added lubricants if you are keeping up with the service intervals and cleaning off the stanchions regularly after each ride.
However there are cases in which inclement weather or harsh riding conditions require the need to lubricate the dust wiper seals to extend their life and keep them from drying out and cracking.
In this instance we recommend Finish Line Stanchion Fluoro Oil Lubricant. This is used to clean out and lubricate the stanchion and dust wiper seals. Available on our website here.
Again the best way to extend the life and keep your suspension components riding at a 100% is to service them at their appropriate intervals. If your suspension is not working properly or making noise I would definitely recommend taking your bike in for service.
Suspension Tips
Here are some excellent tips from one of our very own service tech, Gilbert.
One common mistake that I see on a consistent basis is suspension sag not being set up correctly. In actuality your front and rear suspension should have about the same amount of sag to work in conjunction with each other. Setting it up is really easy to do and here is how you do it:
- All sag must be set while it is in the open position, or not locked out.
- You have to take in consideration what you wear when riding. If you are wearing a Camelback, full face helmet or a tool belt you must account for this by adding around 10 psi to your air pressure.
- Both front and rear suspension should have a movable rubber band on the exposed part of the shocks. Push this all the way down to the wiper of each.
- While having a buddy holding the bike upright, or leaning against the wall gently sit on the seat without bouncing.
- Gently step off the bike without compressing the bike again. Take note of where the o-ring now sits
- Proper sag amount is between 20-30%. Which is about 1/3 of the shock.
Now there are a lot of variables that goes into that number to be covered at a later date.
- Most suspension have a sag guide written right on the body or leg that tells you your percentage. If you have too much sag attach your suspension specific pump and add 5 psi, if you don't have enough sag then subtract 5psi until your desired sag percentage. (Remembering to connect and disconnect the pump after you add air) This process may need to be repeated after logging some break in time on your new bike.
- The end goal of achieving your correct sag will allow you to use all of your bikes travel.
- Tip: After finding the right psi for your suspension always write down the psi for each. If anything should ever happen you always know where your sweet spot is with them.
