Sorry, but it’s true. The basic stuff is some of the most important. So let’s review some of the key things that need checking in order to optimize suspension performance.
Steering head and swing arm bearings: I know, super basic, but if they are loose or worn, your suspension will never feel good, so humor me, and check them.
Inches: Stop using these. Millimeters are much easier to measure and calculate with.
Counting: I know basic huh? But if we are all on the same page it saves a lot of headache. Clickers are counted from fully closed (commonly referred to as full hard, or FFH for short). Completely close the clicker, by gently turning it clock wise in most cases, (some older WP PDS shocks being the exception), and then count out with the first click of any sort being one.
Preload is the only thing you measure the opposite way, winding it all the way off, then starting with zero, and counting actual millimeters of preload.
Fork Pinch bolts: It is critical that these are not over tightened, especially on the lower triple clamp. They will cause serious binding if they are over tight.
Axle pinch bolts: Same here, if these are over tightened they can bring all kinds of harshness back into your fork. Check the specifications.
Static sag (or free sag): This is the distance in millimeters that the bike settles under it’s own weight. It is important to the suspension function that the bike retains some static sag in most cases. Normally the free sag is between 5% and 10% of the total travel.
Rider Sag (also sometimes called ride height, one G, or race sag): This is the amount the bike settles with the rider on in riding position. Many Off-road setups will specify only a total sag number, generally between 90 and 110mm. The general rule of thumb is that the sag should be 25% to 33% of the total available travel. If you are unable to get the total sag number you seek without either too much or too little static sag, you will need to change springs. We will be happy to recommend one for you.
How to measure Sag: With the help of a friend and a measuring tape, follow these simple steps. Place the end of the tape in the rear axle and measure up to a fixed point on the bike, in as straight a line as possible. First physically top out the rear suspension, and record this measurement. Next, let the bike settle under it’s own weight, and record this measurement. The difference in these two measurements is the “static” or “free” sag. Finally, place the rider on the bike in his normal riding position, and record this number. The difference between this and the topped out number is the total, or “race” sag.
Most settings are designed to work within a window of clicker positions. If you find you have to change the position dramatically to improve performance, and are still not happy with the results, it is generally a cry for help from your valving. Stock valving has to cater to a wide range of riders and ability levels, and can’t be expected to be right for everyone. A revalve should be able to get you in a range where we can fine tune for conditions with the clickers.
Compression: The compression clicker is a low speed adjustment that affects how quickly or freely the suspension compresses. By low speed, we mean low shaft speed, or slower movements of the suspension. Faster movements will quickly overcome the clicker, and be controlled mainly by the reaction of the valving shim stack. This is what we tune when we revalve. The stack also has influence on low speed movements, but the clicker is fairly exclusively low speed. With this in mind it is important to remember that it is really easy to make an off road bike overly harsh with the clickers in to tight, and a road race bike lose grip with the compression clickers in too tight. So proceed carefully, and realize that if you need to deviate from the standard clicker setting by a great deal, the shock or fork spec is probably not as good as it could be for you.
If we have done your suspension you should have received it back with a rubber o-ring on the fork leg. This is meant to show you the maximum stroke used. Keep an eye on it when trying to perfect your fork settings.
Fork: As mentioned, too much clicker makes the forks harsh on small bumps. Turn the clicker out till they are as plush as they can be. Occasional light bottoming is ideal as this means you are using all the intended stoke, giving maximum plush ness.
Shock: The same principles apply for compression clicker settings on the shock. Occasional light bottoming yields maximum plush ness. Bottoming can be controlled by turning in the clicker, but be careful of making it harsh on the small bumps. Softer is better, for grip and comfort except in soft rolling whoops or G-outs and sand (where the opposite is true).
Rebound: The same is true for the rebound clicker, and in fact it is just as easy to make a real mess of the suspension function by running the clicker in too tight. The rebound controls how quickly the suspension returns from being compressed. Slowing the rebound with the clicker will hold the suspension down; this can allow it to “pack down” over a series of bumps. Conversely too little rebound will give the bike a wallowy feeling and diminish a rider’s confidence at speed.
Fork: Aside from packing harshness over a series of bumps, excessive rebound can hold the front down on corner entry leading to a tuck. Insufficient rebound will prevent enough weight on the front for good grip, with the front popping up and pushing wide, or climbing out of a berm.
Shock: As we have said, packing down is the number one trouble with excessive rebound. If the back won’t track straight through a series of whoops, or if it kicks excessively over logs, the rebound may be too slow. Too slow of a rebound setting can also hold the back down over acceleration chop and makes the bike feel rough.
Springs & Preload
Springs and Preload: Preload is quite literally, the amount your springs are compressed when installed. By measuring the difference in length of the spring before you put it on (free length), and the length of the spring as it sits on the shock (installed length) you can determine the preload. Some specs will call for a certain amount of preload. Otherwise you can use the sag to determine the appropriate amount of preload.
If we have set up your suspension for you, we will have recommended a spring for you and a window of adjustment with the preload. Preload is necessary to hold the bike up in the position the designer had in mind when he planned it in the first place. If the springs have been chosen correctly, they should yield our baseline sag numbers, while maintaining some static sag. As mentioned earlier we like to see around twenty five to thirty percent of the wheel stroke as sag, with five to ten percent of the stroke as static sag.
Preload is often used as a tuning variable, but like with anything it is important to avoid going to extremes. It is not uncommon to find preload used to band-aid other conditions.
A common problem includes the use of too much preload to band-aid an under sprung or under damped fork. The problem that then arises is that the bike is held high up in the stroke all the time, adversely affecting weight transfer, and sometimes steering. The bike will also tend to want to quickly pop up in front when the brake is released.