could someone explain to me how it works? is it the more air I put in it the stiffer the shock? Do you try to match it with how stiff the rear spring is set at?

 

the purpose of the reservoir is to separate the shock oil from air to prevent the oil from foaming. inside the reservoir body there is a rubber bladder that is pressurized with nitrogen to around 150-200 psi(depending on the shock). thats what the schraeder valve is for. you don't touch it except for rebuilding purposes. and it uses nitrogen instead of air because its more stable. what the nitorgen in the bladder basically does is take up the difference in space that the shock oil creates as its displaced by the shock piston.

 

Thanks so basically I shouldn't try to fill or let out the air or touch it in general.

 

yep.