Until now, we dedicated articles to things less in hand’s reach for most bike owners, so we’re going to turn the page and talk about the most important adjustment you can do by yourself, as soon as you bought your new mountain bike – setting up the suspensions.
Maybe the first feeling that hit you when seeing the complicated systems of modern day suspensions was what to do with all those buttons? They were, at least at first, completely confusing…
From previous articles you should understand that the coil of the suspension stores energy, regardless if it’s a compressed air piston or the classic coil, and that suspension can turn into pogo sticks if the rebound is not properly set. Set by what or by who? The best means of controlling it turned out to be an oil-filled cartridge that runs the liquid through a number of chambers that you shut off or open up between them. We will reach the speed topic in this document, however keep in mind it’s not the classical speed as velocity that reffers to how fast you travel. Mostly, we’ll focus on how fast the suspension compresses, meaning the speed with which the main piston slides inside the oil cartridge.
Suspension buffs 101: the most important setting of a shock is the time it takes to return into the starting position, commonly known as the rebound. It’s usually managed by a red button (save for Manitou products which opted for a reversed colour scheme) at the lower end of the suspension fork’s arms or close to one of the ends in the case of shocks.
Rebound – what in the world is it, what’s its purpose and why can’t we live without it?
The rebound functions controls the speed at which the suspension returns to its initial position. You can also say that the rebound is the force vector opposite to the one that makes the the suspension work. How fast the cartridge or coil comes back in place is a matter that can be settled using this setting by a simple twist, inside its adjustment range established by the manufacturer. In other words put, rebound offers stability, helping the wheel cope precisley with the terrain you ride on, reducing shocks generated by passing over oscillations in the ground.
Somewhat surprising, the rebound is often overlooked, misunderstood or completely ignored by some riders, which makes the shock unused at its full potential. Yeah, bike riding isn’t the same without a proper rebound.
Setting up the suspension fork or the shock. Or both
There is no recipe for the perfect configuration of the rebound. Every riders has its own style or shapes it throught time. So, the most important step in our opinion is getting to the point you can use as a landmark for future adjustments. This point sits exactly half-way of the range of the red button we mentioned earlier. High-end and even some mid-end forks feature a ratchet inside the button to help you acurately find out the level of the rebound suits you best. Usually, the range is divided into 20 clicks, so turning the button 10, gets you in the neutral position. At least in theory, this level should be the optimal one.
You should know that this adjustment goes hand in hand with cartridge pressure or coil tension. For instance, if a 90 psi fork works best at 11 clicks, for 120 psi forks, 16 clicks might prove optimal. Manufacturers provide a list of recommended settings in their user manuals and they didn’t write those things up just for fun. Those are useful documents and giving them a lecture surely is a good idea. Returning to the neutral position, tipical usage implies turning the button no more than 3 to 5 clicks in either way. It means you can reach 15 clicks or 5 clicks, but do not go beyond or under these values.
One can see that RockShox fitted the forks with an important aspect – Rapid Recovery. Its new models have an inner mechanism that sets the rebound at a relatively high speed compared to forks of other manufacturers. Even if you turn it fully up (slow rebound), the suspension will still return in time for the next bump.
Compression – high speed and low speed compression adjustment
Passing on to the next chapter, we get to compression, a rather more complicated and avoided subject.
What is compression, what does it do and what use do we have of it?
Compression adjustments are those settings that sit at the top end of the fork’s arm, for the simple reason they connect to the same oil-filled piston. Their purpose? Reducing the speed at which the piston compresses. Mostly, you will find high speed compression options on downhill suspension forks and seldomly on short-travel forks.
Low-speed compression is the most wide-spread adjustment and its name reveals it deals with low speeds of compression. An example should better explain the situation – when riding down some stairs, the suspension compresses slowly several times, just like when you roll over a mild hill. All that this setting does is to make the fork less sensible to shocks that trigger low-speed compression. It’s similar to the case of brake diving, when too much braking power makes us lean forward. So, we need this setting when tackling a turn, pedalling or braking.
High-speed compression setting kicks in when its put in situations that imply fast compression of the the fork, like when you meet a tall and narrow obstacle. The more clicks, the more resistance they oppose. When riding a deep drop, we should use the fast compression in the first part, when the impact is bigger, and slow compression for the rest of the way, since we already absorbed the shock.
Lockout and Propedal
These two items are tipical for the cross-country and all-mountain range. The lockout blocks the suspension cartridge/coil almost totally, having its best use when riding on paved roads or mild off-roads that imply pedalling.
Propedal is, basically, a mix between low speed and high speed compression, but the manufacturer sets it before shipping out the forks. This setting appeared as a counter-measure to reduce pedal-bob.
Over time, as your ride faster and harder, you will opt for low-compression and a lazier rebound. It’s also true your hands will take in much of the shock. The more aggresive your style is, the more you’ll have to focus on stability and keeping the right position of your body. All these settings work together as one and it will take some time to discover what are the optimal parameters for you.
Author: Cezar Bajenaru