What 3-Way air pressures are you running....

Miker J · Aug 25, 2004

Sorry, more Burner posts. Yeah, I'm one of the "Johnny-come-latelies" to the Turner family. I just couldn't resist the SuperGo deal. A full review of the Burner will follow when I get the time but overall the frame is super. The geometry is spot on for my style.

Anyway, I'd like to know what main air spring and spv pressures you are running in your Burners or other bikes. Iv'e never been a fan of the spv stuff, and while the frame pedals great I feel I'm missing out on a fair amout of sensitivity with the Manitou 3-Way.

BTW, does raising the spv pressure also increase all compressive damping; not just low speed pedal induced, but high speed damping as well?

Thanks,

Mike

Srexy · Aug 25, 2004

65psi in the spv chamber and 120 in the spring. I weigh 158lbs and carry a blowfish w/100oz of water, tools etc - whatever that weighs. I have the bob-knob set to 5 clicks away from fastest (open all the way and back off 5 clicks)

Seems to match up fairly well w/the Noleen up front and can cope w/all but the biggest undulations. Do a search for spv in the shock forum and limit it to thread titles only - you should unearth some decent info.

DLine · Aug 25, 2004

Spv

It took me a good 3 rides with tinkering stops throughout to dial in the shock - occasionally running sections time and time again to get it right over the same terrain. I've found that I like a bit more sag and less SPV pressure than the WORTHLESS manual recommends. I get better small bump sensitivity that way. Here you go:

175lb rider (180ish with gear and water, I guess)
138psi Main Chamber
75-80psi SPV Chamber (depending on type of ride and desired firmness)
Compression knob: 5 clicks from full slow
I'm closer to 30% sag than 25%
I never really notice a harsh bottoming with the shock - IMO it's a good product.

Also - when filling the SPV chamber, I tend to lose a good amount of pressure when I remove the pump from the valve - ie: I pump it up to 80, then remove and replace the pump, and it reads 40. So, to get the desired psi, I overfill to compensate for the leak when the pump comes off. Kind of a hassle - maybe my valve is toast.

Originally, I was looking for an easy to read chart that gives you a good starting point for pressures - and found some on the Giant (VT models) and the Gary Fisher site (Cake). Here's the chart, so I don't have to track it down again:

qcanoe · Sep 1, 2004

just detach that pump and ride?

DLine said:
Also - when filling the SPV chamber, I tend to lose a good amount of pressure when I remove the pump from the valve - ie: I pump it up to 80, then remove and replace the pump, and it reads 40. So, to get the desired psi, I overfill to compensate for the leak when the pump comes off. Kind of a hassle - maybe my valve is toast.

Okay, I have the same problem with my new 3-Way's SPV, and/or with my understanding of how it works. So do a few others, it seems, based on a little surfing. Here's my question (or maybe it's an observation): It appears that the volume of the SPV chamber is truly tiny. It only takes three or four strokes of my small shock pump to get it up to 100psi. After I pressurize the chamber, I detatch the pump. Then of course I have to re-attach it to see where I'm REALLY at, annoying compulsive that I am. Forgetting for the moment about actual air loss, isn't it possible that at that point I'm radically increasing the effective volume of the chamber, just by attaching the pump (effectively making the pump part of the chamber)? Like maybe I'm increasing it by 50% or 100%? We all know from high school Physics that when you increase volume you decrease pressure. To put this question a different way, is it possible that I'm actually NOT losing a significant amount of pressure when I detatch the pump, but that there is simply no good way to measure the pressure that remains in the chamber, because measuring devices all have a major decompressing effect with such a small chamber?

tscheezy · Sep 1, 2004

I think you are correct, but I cannot help but wonder why they use a valve system as poorly designed as shrader for this sort of thing. My old SID rear shock and my Zoke Z1 SL uses an o-ring sealed male plunger-type adapter which slid down into a well recessed valve and those worked perfectly: you know you aren't losing air from the chamber when you remove the pump. With shraders, you always are left wondering. It is certainly the case that some pump heads leave the valve pin depressed as you remove the pump, because if you do it slowly, the shock deflates.

That is such a terrible design it's criminal, and seems to be the case with the Manitoo shocks and the particular pumps I have used, but there is a fix. I found a small o-ring/rubber donut thing I dug out of a shrader valve stem cap which I stuffed down into the pump's head on top of the existing rubber seal. This makes the gasket twice as thick and helps maintain a seal on the valve stem as you are unscrewing the pump. Personally, I would be inclined to just replace the valve stems on the shock with the SID/Zoke style ones I used in the past.

qcanoe · Sep 1, 2004

two-stage pump attachment

tscheezy said:
I think you are correct, but I cannot help but wonder why they use a valve system as poorly designed as shrader for this sort of thing.

Thanks for saying what I was thinking.

There are two problems here:
#1 The generally lame nature of the shock pump / Schrader valve interface
#2 The miniscule volume of the SPV chamber on this shock

#2 means that what normally is simply an inconvenience from #1 becomes a near show-stopper, since tiny errors in attaching / detaching the pump essentially depressurize the SPV section of the shock completely.

As for solving #1, barring a better interface, there is your o-ring trick, and there's also the kind of pump I just got for 20 bucks from Performance after I was driven insane by one of the simple screw-on pumps you're describing. This one screws onto the valve in two stages. Stage 1 creates a seal at the valve stem before any air is allowed into or out of the valve itself. With Stage 2 you screw in a second little doohickey that actually depresses the inner pin on the valve so air can travel between the pump and the shock. Reverse the order of operations to detach. It's working well for me so far, but then it's brand new.

robotkiller · Sep 2, 2004

I am 175-180 pounds

130/90 or 135/90 for smoother conditions.

At 135/90 the bike really flies, but can be a bit rough on less than ideal trails. 130/90 is as plush as I want it to be. Weird how sensitive the shock is.

I like 25%-30% sag , any less and my center of gravity gets a little screwy

qcanoe · Sep 13, 2004

lower presures and faster rebound

Miker J said:
Anyway, I'd like to know what main air spring and spv pressures you are running in your Burners or other bikes. Iv'e never been a fan of the spv stuff, and while the frame pedals great I feel I'm missing out on a fair amout of sensitivity with the Manitou 3-Way.

Well, after three weeks of learning the quirks of the shock (see my other posts in this thread) and tinkering with the settings, I'm starting to feel like I'm getting close to the ideal for weight, riding style, and terrain. I weigh about 135 with shoes, hydration pack, tools, etc. I ride rocky, rooty wet New England singletrack. There are lots of short, steep technical ups and downs but no fireroads or multi-mile ascents (or descents). I'm riding a new Burner, and I'm definitely a spinner, not a masher. Here's what I'm running:

SPV chamber: 50psi (37% of body weight with gear)
Main spring: 100psi (74% of body weight with gear)
Rebound: 6 - 8 clicks in from full fast

Here are the most important things I learned:

1) If your pump leaks any air on removal you are going to have trouble setting the SPV pressure, because under those circumstances setting the pressure is strictly a guessing game. (The chamber is so small that it's impossible to do a "second take" with your pump or any kind of gauge to see if you got the pressure right. This is because you reduce the pressure in the chamber by half or more just by filling the pump or gauge with enough air to get a reading.) So you need to get a good pump fitting, trust the reading, then go ride.

2) No matter which valve core I tried on the SPV valve, if I tightened it enough to hold air, the pin sat too low to be engaged by any pump. So I had to (ever so carefully) file down the top of the valve stem to give the pin sufficient exposure to the pump.

3) The recommendations of many (but not all) to set the rebound a few clicks back from full slow doesn't work for me at all. Where I ride, unless I'm crawling along in 1st or 2nd gear, the roots and rocks come on way too fast and furious for the shock to recover between hits. Speeding the rebound way up was the most important adjustment I made.

Hope this helps someone.

robotkiller · Sep 14, 2004

Does the whole losing pressure thing really matter? It's all relative -- if the chamber is consistently losing the same psi when the pump is disengaged/re-engaged then it doesn't really matter -- just use the numbers as a ballpark and adjust by feel. If the chamber loses the same amount everytime you use the pump then you should be entering the same amount of air with each use.

Incidentally, I have found that using higher SPV pressures (~60% BW) and setting the Main chamber to around 30% sag can give a better combination of plushness + efficiency.

qcanoe said:
Well, after three weeks of learning the quirks of the shock (see my other posts in this thread) and tinkering with the settings, I'm starting to feel like I'm getting close to the ideal for weight, riding style, and terrain. I weigh about 135 with shoes, hydration pack, tools, etc. I ride rocky, rooty wet New England singletrack. There are lots of short, steep technical ups and downs but no fireroads or multi-mile ascents (or descents). I'm riding a new Burner, and I'm definitely a spinner, not a masher. Here's what I'm running:

SPV chamber: 50psi (37% of body weight with gear)
Main spring: 100psi (74% of body weight with gear)
Rebound: 6 - 8 clicks in from full fast

Here are the most important things I learned:

1) If your pump leaks any air on removal you are going to have trouble setting the SPV pressure, because under those circumstances setting the pressure is strictly a guessing game. (The chamber is so small that it's impossible to do a "second take" with your pump or any kind of gauge to see if you got the pressure right. This is because you reduce the pressure in the chamber by half or more just by filling the pump or gauge with enough air to get a reading.) So you need to get a good pump fitting, trust the reading, then go ride.

2) No matter which valve core I tried on the SPV valve, if I tightened it enough to hold air, the pin sat too low to be engaged by any pump. So I had to (ever so carefully) file down the top of the valve stem to give the pin sufficient exposure to the pump.

3) The recommendations of many (but not all) to set the rebound a few clicks back from full slow doesn't work for me at all. Where I ride, unless I'm crawling along in 1st or 2nd gear, the roots and rocks come on way too fast and furious for the shock to recover between hits. Speeding the rebound way up was the most important adjustment I made.

Hope this helps someone.

Srexy · Sep 14, 2004

Some pumps are better than others

I just picked up one of these

from Supergo ($20) and it certainly takes a lot of the guesswork out of it.

Thanks for the recommendation above - I'll give it a shot one of these days.

qcanoe · Sep 14, 2004

Do what works for you

robotkiller said:
Does the whole losing pressure thing really matter? It's all relative -- if the chamber is consistently losing the same psi when the pump is disengaged/re-engaged then it doesn't really matter -- just use the numbers as a ballpark and adjust by feel. If the chamber loses the same amount everytime you use the pump then you should be entering the same amount of air with each use.

If your tactic works for you on this shock, that's great. Obviously you should stick with it. For me, though, the answer was "yes, it does matter." I'm persisting in sharing this experience because it's clear from posts here and elsewhere on the net that others also are having trouble with adjusting SPV on this shock.

When I was using the expensive P.O.S. pump and losing air on disconnect, it was clear that I was not losing the same amount every time. Sometimes there would be NO pressure left in the chamber after I disconnected. (Depress the valve pin and no hiss.) Sometimes there would be "some". So the fact that I pumped the thing up to 100psi every time did not mean that I was ending up with the same residual pressure every time.

So then the next step was to try to figure out what was usually left for pressure after disconnect. The obvious strategy is to pump it up to a certain pressure, disconnect the pump, then measure to see how much is left. Do this a few times to figure out how high you need to go to end up at a target pressue you like. I spent a long time trying this and got nowhere, because, like I said, the SPV chamber is so tiny that the very act of measuring the pressure changes the pressure so radically that you don't know what you've got.

Adjusting "by feel" is actually kind of a long process that takes some attention and requires you to get off the bike and fiddle a bunch of times. I'm happy to do that in the beginning to get the new bike dialed, but after that I want to be able to reproduce that same setup mindlessly "by the numbers," as you say, whenever I may need to. Anyway, getting a pump like the one whose picture Srexy has kindly posted addressed the issue for me.

zkampyman · Sep 15, 2004

Srexy: "You the man"

Big Dog,
Good suggestion, I went to my local Performance store and bought the pump today.
I am building up the new Burner now and a trial experiment with the Manitou had me concerned. Too easy with the new pump, which seems really well built for a Performance pump. I ride in Performance clothes most of the time because:
-they are cheap
-they have minimal logos and solid colors
-their fabrics and sewing seem quite good

But, their tools seem cheesy. This pump is well machined.

Cheers,

Kane

DLine · Oct 4, 2004

*oops*

What 3-Way air pressures are you running....

Miker J

Srexy

DLine

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