Most modern truck systems allow a degree of adjustment to either tighten or loosen them. Usually this is done according to whether you'd prefer to have a board that is light to steer with the ability to change direction quickly, but with a possibility of speed wobbles at higher speed, or a rigid set-up that has stability at speed but turns far less. I would guess that most people settle on a compromise depending on how fast they are likely to go and how well they deal with the wobbles.
Lets take the good old MBS Matrix truck* (later proceeded by the 'Lite' version and then earlier this year by the 'Pro' version). The Matrix had a huge amount of variability on ways you could adjust the truck tension as detailed earlier here. For those people who have forgotten, or can't be arsed to click the link the official options are to: (from brutal to subtle)
a) To move the springs/shocks from inner to outer position to increase tension.
b) To insert shocks, or change them from yellow to orange to red shocks for increased tension.
c) To turn the adjustment screw clockwise to pre-compress the eggs and thus increase tension.
Remolitions Smilie reminds us that MBS 'forgot to mention you kinda have put a bit of compression on the springs. Other wise your eggs are just going to rattle around doing nothing :-)'. Or worse than nothing, they can fall out.
Anyway, options 'a' to 'c' are just the official options. A popular alternative is to switch the MBS egg shocks for Trampa Dampas. The first advantage of this is the additional range of dampas:
Yellow: 65 shore (the shore being a measurement of hardness of a material)
Green: 75 shore
Red: 80 shore
Blue: 85 shore
White: 90 shore
A consequence of using dampas over shocks is that with the dampas being slightly longer, that it is not necessary to crank the springs down as far before the dampa becomes compressed. A repercussion of this being that the springs have less compression when turning starts to take place and so in theory the springs should a) last longer, and b) have less influence on the turning characteristic.
If turning can be improved and a consequence of this is that the springs are really only there to 'hold the springs in', is it worth removing the springs altogether?
The makers of the 'West Coast ultra-light springless kit' certainly think so. Developed by Leon Dove it appears to hold the egg shock in place using a long screw, and then uses a longer bolt so that the truck suitably compresses the shock. Those thinking of purchasing a system should bear in mind that only orange and red egg shocks are recommended (dampas bend apparently), and that relatively new top hangers are required so that everything lines up nicely. However, fans of the system rave about fantastic progressive turning and no speed wobbles!
Some words from Leon himself can be found on Remolitions pages here with EvilC's review here and a few more pictures by Mikael here from the popular pages of Surfing Dirt.
But that's not all; there is the option to have different shocks or dampas in the front and rear trucks with a popular option to have stiffer ones in the front to aid stability at speed, with less stiffness to the rear to aid turning. Of course, other variations exist as well as more complicated mathematics if you start to take into account truck angle and the suchlike. I looked at it once in the hope of coming up with a model to allow people to select the various options and get an idea of how their set-up would compare to others. However, the maths got in the way and nothing ever came of it.
As an aside, all these options in truck tensions make me wonder how much your available kit defines your style of riding. For example, when I started riding, I would like to bomb the local hills and so was encouraged by other local riders to insert green dampas. Had I stuck to yellow egg shocks, would I have been more inclined to carve out of necessity or would I have excelled at bombing hills on loose trucks? Hmm, another post for another day.
(* - Disclaimer: Other trucks exist, but I haven't ridden then, though the theory should be similar...)
