Newbie question.. Pumping air forks...

JxL

Finally got some air forks, which really needed more pressure. Received my Rockshox 300psi pump and positive measured at 70psi and negative at around 50psi.

I pumped them up to 100psi (im around 65kg), but when I unscrew the pump out there is a noise of air coming out, and when attaching again, it shows up as lower than I left it.

Also, what is the black button for? And what is the correct way of adjusting pressure without air coming out?

Tried searching on google but it only came up with places to buy the pumps!

Thanks!

ben-1888

iv just got air shocks aswell with what sounds like the same pump... i am no expert but think u should pump past what u are wanting then usin the black button let some air out and drop down to your desired pressure. thats what i do anyway... but im similair weight as you and i was advised to have about 130psi or there abouts on pos and neg... but i dont no much about that to be honest. as for the air escaping when you takr the pump off just add a little extra before removing. Hope this helps!

alaric@epicmtb

Common schoolboy error

When you disconnect the pump, what you hear is the pressurised air escaping from the pump hose. So long as you unscrew it quickly the valve will seal the shock pressure chamber with no significant loss of air - any loss will be approximately the same each time anyway, so if the bike rides well with the pump reading 100psi that's all you need to know, it doesn't actually matter what the exact value is. Too soft add more, too hard set less next time...

The reason the gauge always reads low on reconnection is that air from the pressure chamber has had to fill the pumps hose. Since the pressure chamber is very small this loss has a significant effect on the pressure.

Bottom line is that you cannot "check" the pressure on a fork or shock - you have to pump it up every time.

Alaric.

nicklouse

please make yourselves aware of the FAQs here http://www.bikeradar.com/forum/viewforum.php?f=40043.

alaric@epicmtb in a way you can.

JxL

Brilliant, thanks a lot for all your help! Sorry Nicklouse, I used the search function with no relevant results and missed the FAQ

@Ben1888

What forks do you have?

Mine are Reba Team 09's with 100mm travel. The manual says for 63-72kg is recommended 90-105psi (Dual Air).

ben-1888

its my rear shock that i have at 130 psi... miss read ure post but i also have air forks marzocchi 55r... im not sure what i have them at, i change it all the time not very high though!!

Lapierre t 400

I have dual air 2008 reba teams pump them up to 100 psi positive chamber and 120-130 psi negative chamber
I weigh ish 65kg when going out for ride

JxL

Lapierre t 400 wrote:

I have dual air 2008 reba teams pump them up to 100 psi positive chamber and 120-130 psi negative chamber
I weigh ish 65kg when going out for ride

Sounds about the same, although RS doesn't recommend going above the positive by more than 15% (but if it suits you I guess its fine)

Now I am getting 15mm sag. Is this about right?

EDIT::

the forks seem to be MUCH more responsive and bouncy than my old oil forks. Haven't been for a ride yet but hope it will turn out well!

Dirtydog11

Now I am getting 15mm sag. Is this about right?

Adjust the positive pressure accordingly until you get 15 - 25 mm of sag (the black button on the pump is an air bleed screw for letting air out).

Make a note of the air pressure!!

ie: If your positive pressure is 120 psi then set your negative pressure to 120psi.


Your now in a position to fine tune by either adding or removing air from the negative side (+/-15psi).

Having a greater pressure in the negative chamber than the positive chamber will make the forks more sensitive to small bumps / rider induced bob.
ie: Positive side 120psi Negative side 130psi ("plush")

Having less pressure in the negative air than the positive will make the forks less susceptible to rider induced bob/small bumps.
ie: Positive side 120psi Negative side 110psi ("less plush" )

You might have a problem setting the negative side accurately with a 300psi pump. I guess it would go up in 10psi increments?

Hope this helps.

FYI. The compression adjuster on the right hand leg of your fork has a recess under it for tucking in the excess cable( I noticed it was sticking out on your photo). Its called a nip and tuck spool .I've renamed it a nip and f**ck spool because its a right pain to get the cable tucked away properly.

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supersonic

Also if your poplock has a blue dial you can adjust the compression damping to tune further.

I don't like none adjustable poplocks.

Dirtydog11

supersonic wrote:

Also if your poplock has a blue dial you can adjust the compression damping to tune further.

I don't like none adjustable poplocks.

Shhhhh, He's got the pushloc.

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JxL

Dirtydog11 wrote:

supersonic wrote:

Also if your poplock has a blue dial you can adjust the compression damping to tune further.

I don't like none adjustable poplocks.

Shhhhh, He's got the pushloc.

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Nop, the standard poplock I'm afraid! No adjusting for me... Ah well Hopefully I can get close enough with positive/negative pressures. Tried searching for the adjustable one but no place sells them, and I bet they're very expensive for what they are.

Thanks for the help everyone!