air shock tech

[Mr.Ed]

 OK, so I got a risse genesis, along with a vanilla rc, and a stock nr4... heres the question

I pump up the risse to 250 pounds (  I am 180 ). It should'nt sag , right? But ..ahh it does, about an inch. So I try this several more times.250 pounds, 300 pounds, It still sags, but I do not hear any blowoff of air, and when I check the pressure, it's still around what I put in, aside from the small amount lost from removing the pump.

Whe I remove the pump I seem to lose about 15 to 25 puonds of pressure. However , if I put 250 psi in, it still should'nt sag when I am 180 pounds.

I know I should'nt need 250 psi, That is just what I went up to when I realized that 180-190 psi was'nt going to work.

i emailed risse, but still await a response. Any thoughts?

[shovelon]

Yikes,

250 seems way too much. My manitou takes 115 main and 65 spv, for a total of 180. I weigh 190.

Terry

[Colin]

dunno about air shocks but on coil and Oil ones you do want some sag. Other wise you're sitting on the top end of the travel and there's nothing there for it to follow the terrain and the shock will keep "topping" out which I guess is just as bad as Bottoming out frequently.
I would imagine the same would be true for an air shock.

But...... the recommended sag on a Coil/Oil job is about 12mm of spring compression not an inch!
If there was too much you would tighten the spring pre-load but what can you do on a Air shock as the equivalent of this?
If you end up tightening the pr-load too much and still can't achieve the optimum "sag" then a stronger coil is needed.

All this probably doesn't help much other than to affirm that there does indeed seem to be a problem, but maybe someone with more air shock experience than me can help more!

[Mr.Ed]

 I am using my Vanilla now, and all is well and good.

Its the air shock I can't figue out. 250psi  IS way too much, for my 180 pounds anyway. I would think with that much pressure in it, it would'nt sag at all. But it does...any one here ever rebuild a risse. I know I can do it, just need a rebuild kit.

I t does not seem to be leaking air. Could the internals need adjusting? is what I'm looking for, maybe ?

Ed

[Simon]

Are you using the recommended ACCU-FIT ADAPTER recommended by Risse,this prevents excess air loss from the shock when removing the pump
I'm using an Astro5 shock and run at around 260lbs pressure giving 8mm of shock sag,I'm 168lbs.
Simon.

[Mr.Ed]

 Simon, what is this Accu-fit adapter you say?

This shock is used, but new to me. I do not have any original paperwork, as I have never heard of this adapter.

[Simon]

Simon, what is this Accu-fit adapter you say?

This shock is used, but new to me. I do not have any original paperwork, as I have never heard of this adapter.

Hi Mr.Ed
I got it slightly wrong,its a ACU-Fill adapter and you should be able to get one direct from Risse,mine was supplied by CVI in the UK along with my Risse shock.
http://www.risseracing.co.uk/imgs/Acu-fill.jpg
Simon.

[Mr.Ed]

Thanks Simon,

I don't seem to have that. All I see is what looks like a schraeder valve. I shall give that a whirl and see what comes of it..
Ed

[junkster]

Hi,
  could it be simply the shock is on its way out/worn - the shaft of my rear stratos xc pro air/oir sags nearly an inch (well prob 3/4s) and I have simply put it down to wear n tear. Have done a lot of mods using it and it was probably used very slightly out of alignment for a while. Stikll works, is at 280 pressure (I am around 210)

warranty?

D  [smiley=nod.gif]

[Mr.Ed]

No warranty, ......  I will try to do what I can.....I emailed Risse about a rebuild kit ....
I was considering getting a new astro 5 anyway...also have other shocks ( back-ups )

I just like the way the bike weights 1 and a half pounds less with the air shock....compared to the Vanilla...but I really like the vanilla's damping.

Its a trade-off, no?

[Simon]

Have you checked if the pump gauge is reading the pressure correctly ???I have a shock pump thar reads incorrectly by over 20psi,
I noted in your first posting that after you have inflated your shock that when you re-check the pressure is still around as you set it
this means there cannot be a fault in the air chamber because it either leaks and you lose pressure or it doesn't,once the air pressure bypasses the piston seal it goes straight to atmosphere, if pressure entered the damper chamber oil would enter into the air chamber and you would get oil coming out of the schraeder valve as you removed the pump,
the only real trade off between coil over and air is that the air spring is affected by temperature allowing the spring rate to change in differing temperatures,coil over is a lot burlier and is well suited to more extreme riding etc.
Simon.

[Mr.Ed]

 " if pressure entered the damper chamber oil would enter into the air chamber and you would get oil coming out of the schraeder valve as you removed the pump"...........

Simon,  If this happened would the pressure gauge read the same as it did when I pumped it up? I do recall a small amount of oil coming out when I first pushed down on the valve. However oil does not come out when I remove the pump.....So what I could have is a bad seal internally, allowing oil bypass. And low oil in the shock because of it. ??

When I get home from work tonight, I will push the valve in again and see if oil comes out.

Ed

[Simon]

The pressure would read the same as the air would bleed back ito the air chamber,you only get a weep of oil from the schrader valve (I did with mine).
The air chamber is rebuildable by the enthusiast but unfortunatly the damper requires specialist tools,I know this from experiance as I had to have mine rebuilt recently,I could rebuild the air chamber and change the oil but the system wouldn't bleed because of a blown damper seal,it worked out cheaper for a specialist rebuild.
Simon.