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Regarding solo air forks everything is clear. Once we bumped both chambers pressure is equal. But why for dual air forks air pressure doesn't try to get equal in both chambers? What's the point of second chamber if it has different pressure and doesn't try to equal it?

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I would too like to hear an answer for this question, however, I especulate that it doesn't matter that much, as the bridge that joins the two lowers of the fork mechanically links both springs. I get this from forks that only have one coil spring, or ones that have two coils but only one preload adjustment knob. I also use an air fork with one damaged side that leaks all the air in a few minutes, but the other side holds up all the load without any kind of complaint. –  Jahaziel Jun 25 '14 at 23:17
Generally forks have the spring in one leg (either coil or air (both chambers)) and the damper in the second leg. –  DWGKNZ Jun 26 '14 at 1:51

1 Answer 1

The negative air chamber provides resistance to the positive air chamber. It controls the speed air spring returns to its initial shape. The chambers are isolated so the air is unable to equalise.

The positive chamber provides resistance against compression, essentially how hard is the fork.

The third part of the suspension action is dampening, the negative air chamber controls the forks return and the damper stops if from oscillating and provides a smooth ride.

Rockshox explain dual air below quite well in suspension terms.

enter image description here

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But if negative pressure is more then positive does it reflect in fork travel? Does fork compress in this case? –  Johnny_D Jun 26 '14 at 12:09

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