What to do with Rear Air Shocks?

[GabrielGoes]

Whats up guys i've had my bike for about a year now and i have yet to change the shocks.. some surface rust on them but they look okay, i was wondering if they needed maitenence ? i know for sure their air shocks because thats what people told me including the p/o... what are air shocks btw? do they need to be filled with air again? thanks...
-Gabe

[Steve]

Are they "air" shocks or "gas" shocks?

Yes, there is a difference.

"Air" shocks will have a small line (about 1/8") going between them, then to a fill point. Sometimes AIR is the only spring (S&W shocks did this), sometimes air is a supplement to a coil spring (Progressive has a model like this).

"Gas" shocks are typically rather normal shocks, but have a bladder inside that is pressurized (typically with nitrogen) to keep the damping fluid from foaming, ensuring more-consistent operation.

As usual, a couple of pictures would tell a lot.

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[GabrielGoes]

Hey thanks for replying steve.. these are "air" shocks i believe.. they have this thin black wire comming from them which i dont think i ever bothered following.. am i supposed to fill it up with air somwhere?

[Steve]

Yep, those are "air over coil" shocks.

The coils will handle most of the weight, the air is for anything additional.

To determine whether you need any air, check your "sag". Either start with the bike on the centerstand to fully extend the shocks or put it on the side stand and pull up on the back to make sure the shocks are fully extended. Measure the shocks from eye to eye. Now sit on the bike, try to put a little weight as you can on your toes to hold you upright while a helper makes the same eye to eye measurement. You want to use no more than 20-25% of your available travel when you sit on the bike.

Most shocks have about 4 inches of travel, so you only want it to drop 3/4 to 1 inch. If it drops more than that, you need to find the other end of that hose and add a bit of air. With the coils on there, you might not need more than 10-20 psi, so add carefully. Not sure what the pressure rating might be on those shocks so you want to add very carefully.

I had S&W air shocks on my KZ1300 about 30 years ago and loved them. They were an "air only" design, so you had to be sure there were no leaks in the system or you would be riding a low-riding hard-tail. I found that 80psi would give a very nice ride with just me. If Mrs. Steve joined me on a ride, I put in 110psi. I had a gauge on the handlebar to monitor what was happening, it was interesting to see the needle moving as we rode. Had another gauge for the air forks, too.

If you have plans on removing them, let me know, I might be interested in them.
(EDIT: I just noticed that they are eye/clevis design and probably won't work too well with anything I have. )

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