Ich hab ma ein paar Sachen von MTBR rausgesucht, meist sind die Statements dort recht Technisch fundiert:
With all due respect I must disagree with you. The limits for the IFP chamber is 50 to 175psi. and that is in the manual. You are suggesting a very high pressure. There is no mention in the manual about a minimum pressure "so that the piston can be pressurized". I would suggest that you start at about 100psi. and play with small changes to find what you like. Much above 100psi. makes the shock harsh. Personally I think that you want it as low as possible. I run mine at 60psi. and I'm 220lbs
I've been running my Evolver 6 on my Nomad for several months now. I'm 185lbs. and run the main pressure right at my weight and the bottomout pressure at 60psi. I realize the bottomout chamber has an effect through more of the travel range than just bottomout, but that is supposed to be its primary function
Running 75 in the IFP, but until I can ride it harder I wouldn't have any idea how this really affects the stroke. Shock is mounted on a Transition Covert.
BTW- I just got mine back from a rebuild/refresh. Yes, I can confirm what was posted earlier by pvflyer, you have to run at least 150psi in the piggyback. It's not a variable pressure thing like the SPV chambers on other Manitou shocks. If you don't keep it properly pressurized, the IFP can move out of the correct position, causing a loss of travel. This happened to me when I was running low pressures in there thinking that's how it worked. I lost about .25" of stroke.
I have all my travel back now. Woot!
.I see this higher pressure...140-150 psi...deal keeps coming up for the piggyback air charging. I've tried that pressure on mine, and the shock did not perform well at all. Small bump compliance got very harsh and the bottomout performance got strong enough to limit travel.
The one thing that I find confusing in this situation is the fact that I'm pretty sure the IFP design in the Manitou air shocks is basically the same in the Intrinsic and SPV models, and that the difference is in the circuitry of the valving as to how the pressurized IFP will affect the shock's operation. Now...if Manitou's IFP is designed to operate with integrity at pressures as low 50 psi for the SPV models, why is it not capable of operating at 50 psi in the Intrinsic mode? My understanding of the difference in piggyback operation between the SPV and Intrinsic air shocks is that both models have the circuitry that influences bottomout performance, but the Intrinsic models do not have the same circuitry that affects pedal platform like the SPV models. Note, that I didn't say that there is no small bump compliance influence when you jack up the pressure in the piggyback in an Intrinsic model...but it is not a true pedal platform as contained in the SPV model.
I've had two and currently still have one 4-Way Air SPV shock on one of my Bullits. This shock operates with full integrity at low SPV pressures as long as you don't let it go below 50psi. I can't see why the IFP in the Intrinsic models would be so completely different, when all Manitou really had to do was disable or modify the circuitry that created pedal platform...simplification instead of complication. Now...I realize that there may be a totally different issue going on here in the ISX-6 that indeed might require a wholly different approach, but it doesn't seem logical.
I've just taken another look in my manual that came with my shock. There is absolutely no mention anywhere that the pressure must be set to a fixed "150psi". They do however lump it together with SPV shocks though with the pressure range of 50 to 175psi. If it was meant to be run at a fixed 150psi. I think they would have said so.
I have also previously had a look to the online service manual and the shocks are covered together. The SPV shocks appear to be exactly the same except they have a SPValve on the piston and shocks like ours have a shim stack.
The way I understand it is that the pressure in the IFP controls compression damping. More pressure, more compression damping. That is why there is no small bump compliance at high pressure. There is too much compression damping, Of course there is the further option of changing the slope of the compression by altering the volume.
I've been using mine with 60psi. in the IFP for almost a year and there have been no problems. The small unit in the cone connecting the main body and the IFP has a small unit they call the Intrinsic unit. It has the high and low speed compression controls on it. I think that unit is what really is the difference between the shocks. The ISX-4 has the Intrinsic unit but no High and low controls.
To report back, I phoned Manitou earlier and left a message with their technical help line. I just got a call back and asked the question about the pressure in the IFP. I was told that it can be anywhere from 50 to 175psi. with no ill effect and he suggested that I start out from about 100psi. and go up and down. I think he thought I just got the shock.
Jedenfalls passt das anscheinend mit 50-175PSI,
hab jetzt nicht alles gequotet, jedenfalls gibt es anscheinend einen Manitou Service Mitarbeiter der das mit den 150 festen PSI in die Welt gesetzt hat, aber telefonisch
haben sie 50-175PSI bestätigt im Manual haben die das einfach mit den SPV Modellen zusammengeworfen, jedoch auch auf die Intrinsic Dämpfer übertragbar.
Und nun wieder zu meiner Theoretischen ansicht:
Wenn ein fester Wert von 150PSI erforderlich wäre, warum die Möglichkeit bieten die Luft zu verstellen? Gibt Dämpfer wie den alten Vanilla RC oder aktuell den Vivid, da ist
kein Luftventil vorhanden da im Piggy in fester Wert ist, wäre ja hier dann auch der Fall, oder? Desweiteren heist der Dämpfer ISX-4 oder 6, die Zahl ist indikator dafür was verstellbar ist:
4:
-Luft Hauptkammer
-Luft Piggy
-Zugstufe
-Volumen Piggy
6:
-High
-Lowspeeddruckstufe
wenn der Druck im Piggy ein fester Wert wäre, müssten die Dämpfer ISX-3 und 5 heissen.
Und wie ich schon sagte, warum sollte das nur wegen Intrinsic anders sein als beim SPV Dämpfer? Wenn 50 PSI bei einem SPV Dämpfer reicht um den Trennkolben unter druck zu halten, warum dann nicht bei einen SPV? Die ganze Intrinsic und SPV Geschichte Spielt sich rein auf der Kolbenstange ab, das hat in erster Linie erstmal wenig mit dem Piggy zutun, deshalb bin ich mir da sicher das sich da Technisch nichts unterscheidet.