ichnusa Posted November 25, 2010 Share When pumping a dual-air system, which should be done first? Positive or negative? Should you check first after finishing the second? Surely they have an influence on each other... Link to comment Share on other sites More sharing options...
stewie911 Posted November 25, 2010 Share RS recommend that the negative should never be more than 20psi higher than positive. (Could maybe only be to cover their asses) My positve has been at 0psi and negative at 130psi. Still works fine Link to comment Share on other sites More sharing options...
Brighter-Lights Posted November 25, 2010 Share Deflate negative first. Then pump positive, then pump negative. For RS forks I like positive + negative the same. Link to comment Share on other sites More sharing options...
covie Posted November 25, 2010 Share any over 90kg riders on a 2010 or 2011 reba, would be interesting to know your pressure settings? Edited November 25, 2010 by covie Link to comment Share on other sites More sharing options...
Rubel Posted November 25, 2010 Share Excuse my ignorance but which one is positive and which one is negative....top or bottom? Thanks Link to comment Share on other sites More sharing options...
Bike Mob Posted November 25, 2010 Share Positive top - inflate 1stNegative Bottom inflate second. Pump pos to 100, then neg to 100, then recheck pos and set to desired level. Unless you know what sort of bump compliance you want, Make them equal. remember you lose some air when disconnecting the pump. So i pump the pos over 15psi and the neg 20 psi to compensate for losses. I like my positive chamber 10psi harder for a firmer ride. less prone to sag. if you want more sag or softer initial feel on bumps then set neg chamber 10psi harder than pos. Edited November 25, 2010 by Tarmac-SL3 Link to comment Share on other sites More sharing options...
Johan Bornman Posted November 25, 2010 Share remember you lose some air when disconnecting the pump. So i pump the pos over 15psi and the neg 20 psi to compensate for losses. This could happen, but it depends on your pump's design. Most pump heads have no pin to depress the valve. They rely on higher air pressure on the one side to push the valve open. Thus, with each pump stroke, the valve opens and closes at the end of the stroke. The pssst you hear when you remove the pump head is the air in the tube escaping. The fact that the pressure suddenly drops on the upstream side of the valve makes it close automatically. You can clearly hear the valve open and snap close when you pump your wheels. As you know, sometimes (always) the valve is stuck and the pressure rises high before it bursts open and allows pressurised air from the pump hose to enter the tyre. Some shock pumps have a pin if sorts to open the valve but this is not a feature, it is a hinderance. It adds one extra step to the process. Life is too short. Link to comment Share on other sites More sharing options...
SURFER Posted November 26, 2010 Share Positive top - inflate 1stNegative Bottom inflate second. Pump pos to 100, then neg to 100, then recheck pos and set to desired level. Unless you know what sort of bump compliance you want, Make them equal. Let all the air out of negative (Bottom), pump positive (top) to desired pressure and then do the bottom - RS reba Link to comment Share on other sites More sharing options...
Headshot Posted November 26, 2010 Share The neg chamber influeneces small bump sensitivity - i.e it helps make the fork feel a little softer initially. I am still experimenting with my 2010 reba and have just reduced the positive as I found it too firm on uphill rockgardens and slow rocky descents. Tradeoff is it feels a little too soft on the faster rocky stuff... great fork tho - sues all its travel and well damped. Link to comment Share on other sites More sharing options...
Top Fuel Posted November 26, 2010 Share This could happen, but it depends on your pump's design. Most pump heads have no pin to depress the valve. They rely on higher air pressure on the one side to push the valve open. Thus, with each pump stroke, the valve opens and closes at the end of the stroke. The pssst you hear when you remove the pump head is the air in the tube escaping. The fact that the pressure suddenly drops on the upstream side of the valve makes it close automatically. You can clearly hear the valve open and snap close when you pump your wheels. As you know, sometimes (always) the valve is stuck and the pressure rises high before it bursts open and allows pressurised air from the pump hose to enter the tyre. Some shock pumps have a pin if sorts to open the valve but this is not a feature, it is a hinderance. It adds one extra step to the process. Life is too short. Surely this is not true. If you connect the pump you would not get a reading? Only once the pressure opens it. Just doesn't sound right to me. My pump has a pin in it so when you connect it the valve will open so you can get a reading. Otherwise explain how it gives a reading when you connect the pump. Link to comment Share on other sites More sharing options...
Johan Bornman Posted November 26, 2010 Share Surely this is not true. If you connect the pump you would not get a reading? Only once the pressure opens it. Just doesn't sound right to me. My pump has a pin in it so when you connect it the valve will open so you can get a reading. Otherwise explain how it gives a reading when you connect the pump. I think you've already explained it. If you get a reading from just connecting the pump, clearly there is something there opening the valve. The pumps I use don't work like that. Connect and no air goes into the pump. If you want to get a reading, you pump until the air pressure in the pump hose and shock is equal. You listen for the valve opening and then take your reading. Now, when removing the hose, none of the pressure in the shock is lost. Some others I've seen have a screw-in pin, so you can choose how to open the valve - with air pressure or manually. Link to comment Share on other sites More sharing options...
Johan Bornman Posted November 26, 2010 Share Surely this is not true. If you connect the pump you would not get a reading? Only once the pressure opens it. Just doesn't sound right to me. My pump has a pin in it so when you connect it the valve will open so you can get a reading. Otherwise explain how it gives a reading when you connect the pump. I think you've already explained it. If you get a reading from just connecting the pump, clearly there is something there opening the valve. The pumps I use don't work like that. Connect and no air goes into the pump. If you want to get a reading, you pump until the air pressure in the pump hose and shock is equal. You listen for the valve opening and then take your reading. Now, when removing the hose, none of the pressure in the shock is lost. Some others I've seen have a screw-in pin, so you can choose how to open the valve - with air pressure or manually. Link to comment Share on other sites More sharing options...
Punt Posted November 26, 2010 Share Just for the record... I have no idea what you guys are talking about Link to comment Share on other sites More sharing options...
david16v Posted November 26, 2010 Share Just for the record... I have no idea what you guys are talking about Penis pumps! Link to comment Share on other sites More sharing options...
covie Posted November 26, 2010 Share Ok inflated + to 120 and - to 110 will see how it goes, whats your floodgates set too? Link to comment Share on other sites More sharing options...
wapad Posted November 27, 2010 Share Ok inflated + to 120 and - to 110 will see how it goes, whats your floodgates set too? I cant remember off hand I weigh 100kg so I think it is set about 4-5 clicks from full closed what I did find is when you set the floodgate that using bodyweight to push down in a stationary position doesnt exert as much force when ridiing in the standing position even on incline so fiddle with the floodgate on a ride and not in the back yard the Reba is great if you want to fine tune, I ride Tokai quite often so have set it for that sort of riding Link to comment Share on other sites More sharing options...
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