Answered Shock pump issue

[Beekeeper]

I don’t quite see the point of putting air in my shocks because it all comes rushing out as unscrew and remove the pump
Any advice?

 

[Zimmerframe]

I don’t quite see the point of putting air in my shocks because it all comes rushing out as unscrew and remove the pump
Any advice?

Professionals normally have a hyperbaric chamber to work in when doing their shocks. You just go in and set the interior pressure to the same as desired in the shocks, then the air can't rush out.

Normally .... when you unscrew it, the valve pin releases before the seal breaks sufficiently - so air doesn't normally escape. Which shock pump are you using ??? I think you have a RockShox Recon Air 100 mm ?? if I remember correctly ?

 

[ifu03558]

why dont you try unscrewing it really fast...only kidding you do know that the air that escapes when you unscrew the pump is from the pump and not the shock/fork? Thats why the fork/shock has a valve to stop air escaping when the pump is taken off.

 

[KennyB]

In my pumps that air coming out is from the pump itself. Do you unscrew the pump first, then the bit that screws into the valve? Have you tried reattaching the pump, and checking if you have really lost any pressure?

 

[Beekeeper]

Professionals normally have a hyperbaric chamber to work in when doing their shocks. You just go in and set the interior pressure to the same as desired in the shocks, then the air can't rush out.

Normally .... when you unscrew it, the valve pin releases before the seal breaks sufficiently - so air doesn't normally escape. Which shock pump are you using ??? I think you have a RockShox Recon Air 100 mm ?? if I remember correctly ?

Front RockShox Silver Judy.
I think I’ve solved it now. I wasn’t tightening it up enough so when I re-read the pressure it always said zero. All ok now

 

[Beekeeper]

I was obviously creating 110 psi in my pump adaptor tube and not my shock. Schoolboy error ?

 

[ifu03558]

In my pumps that air coming out is from the pump itself. Do you unscrew the pump first, then the bit that screws into the valve? Have you tried reattaching the pump, and checking if you have really lost any pressure?

unscrew the pump from the shock valve, if you reattach the pump to the shock it will read as lower pressure as the air goes into the pump.

 

[Zimmerframe]

I was obviously creating 110 psi in my pump adaptor tube and not my shock. Schoolboy error ?

Don't worry, you're not the first and won't be the last !

If it makes you feel any better ... before I bought a shock pump I thought I'd check the pressure with a tyre pressure gauge .... ........ it exploded ...

 

[KennyB]

unscrew the pump from the shock valve, if you reattach the pump to the shock it will read as lower pressure as the air goes into the pump.

Granted but the small amount of air lost into the flexible adaptor is not going to lead to a zero reading.

 

[Beekeeper]

Don't worry, you're not the first and won't be the last !

If it makes you feel any better ... before I bought a shock pump I thought I'd check the pressure with a tyre pressure gauge .... ........ it exploded ...

Glad it was your pump and not your lungs if you were to open a window for some nice fresh air whilst in your hyperbaric chamber ??

 

[ifu03558]

Granted but the small amount of air lost into the flexible adaptor is not going to lead to a zero reading.

Why are you getting a zero reading? You are doing something wrong, either you aren't screwing the pump on correctly or its something else. Are you using a shock pump and not a pump for tyres?

 

[Beekeeper]

Why are you getting a zero reading? You are doing something wrong, either you aren't screwing the pump on correctly or its something else. Are you using a shock pump and not a pump for tyres?

I wasn’t screwing it on properly. I’ve now realised the errors of my ways

 

[KennyB]

Why are you getting a zero reading? You are doing something wrong, either you aren't screwing the pump on correctly or its something else. Are you using a shock pump and not a pump for tyres?

Not I, the original poster.

 

[Mikerb]

Easilly done with some pumps...or maybe it is the valve...or indeed the match between the pump and the valve. I can screw my pump onto the valve of my shock and get a reading on the pump but sometimes if I then decide to add pressure there is huge resistance in the pump. Screw the pump onto the valve another quarter turn and everything works fine. So the action of opening the valve with the pump really has 2 stages with that valve. The first stage is the valve sufficiently open to pressurise the pump but not enough to enable air to pass from the pump to the shock. 2nd stage is when the valve is fully open. Strangely this only occurs on my shock whereas on the forks I do not get that issue so I guess it is down to the shraeder valve in the shock. I know now to be extra careful to ensure the pump has fully opened the valve on the shock.

 

[Shandy]

Hi. anyone have a link for 19 levo default shock pressure/weight setting sheet. When initially picked the bike up they set to my weight, I've played about with the settings but just wanted to see the difference ..

 

[Mikerb]

Air pressure in psi equivalent to your all up riding weight in lbs is a start point. Sag of 30% seated or in the action position dependant on how you mostly ride. I am c 80kg and have my shock at 205.

 

[Shandy]

Air pressure in psi equivalent to your all up riding weight in lbs is a start point. Sag of 30% seated or in the action position dependant on how you mostly ride. I am c 80kg and have my shock at 205.

Cheers

 

[Beekeeper]

Air pressure in psi equivalent to your all up riding weight in lbs is a start point. Sag of 30% seated or in the action position dependant on how you mostly ride. I am c 80kg and have my shock at 205.

It was pretty easy to stand on scales with backpack on and lifting the bike. Total weight was 130kg. 130psi feels perfect

 

[ifu03558]

Why you lifting the bike?

 

[Zimmerframe]

Why you lifting the bike?

Beekeeper STRONG !

I guess 90% of the bike, beekeeper and his gear are all sprung weight - presuming he has no bees attached creating a lifting force.

 

[Mikerb]

He has lost me on that one!! Assuming the bike is 22kg the rider weighs 108kg meaning a good start point for pressure in the rear shock would be c 240 psi!!

 

[Zimmerframe]

He has lost me on that one!! Assuming the bike is 22kg the rider weighs 108kg meaning a good start point for pressure in the rear shock would be c 240 psi!!

His equivalent rear shock pressure is considerably higher than 240psi .... it's a hardtail

 

[tedturbine]

He has lost me on that one!! Assuming the bike is 22kg the rider weighs 108kg meaning a good start point for pressure in the rear shock would be c 240 psi!!

He was originally discussing Front RockShox Silver Judy.

It seems to me at least, that a very approx starting point is your weight in kg for psi for forks and for rear shocks your weight in lbs for psi.

My fox bouncy bits are around this ballpark, forks a bit less and shock a bit more but I did the setup per fox's instructions so did the whole add 30psi, cycle fork / shock, repeat then start measuring sag and set based on that as a baseline.

 

[Beekeeper]

Why you lifting the bike?

To find total weight. Only room for my feet on the scales so I need to lift the bike off the floor to find total weight. Also wearing backpack, helmet, massive D lock. Wanted to know the total torture I put my bike through

 

[Beekeeper]

My front forks also have a sticker on which says for E-bikes add an extra 10 psi

 

[Mikerb]

Not all of the bike's weight acts through the rear shock....unless you have a horribly imbalanced bike!! The 10psi sticker on the forks is put there by the manufacturer and takes no account of the tuning changes ( porting/volume spacers etc) the brand may have implemented compared to the stock fork......so somewhat irrelevant I reckon.

 

[ifu03558]

To find total weight. Only room for my feet on the scales so I need to lift the bike off the floor to find total weight. Also wearing backpack, helmet, massive D lock. Wanted to know the total torture I put my bike through

Aye, ive never took the weight of the bike into account when setting sag? I've never heard of anyone else doing it either, yourself apart of course.

 

[GrandPaBrogan]

I don’t quite see the point of putting air in my shocks because it all comes rushing out as unscrew and remove the pump
Any advice?

You know my old pump looks similar to your pump @Beekeeper and I get the same problem. If I don't time it right and twirl it out fast enough, a considerable amount of air from the shock rushes out. And it's not just the air coming from the pump gauge and hose. The screw connector of the pump presses the valve as it goes in, but when unscrewed - air can escape through the threads before the connector 'nib' can back off far enough for the shock valve to be closed beforehand. If I'm slow, as much as half the air pressure I pumped in can escape.

The newer pumps, like the Rockshox pump has a rubber sleeve that seals around the threads before it pushes the valve open, and so when the pump screw connector is being withdrawn, this rubber sleeve keeps the threads sealed until the valve is fully closed. Simple but effective.

I just bought a GIANT shock pump that has a two stage connector (like what Zimmerframe mentioned early on). There is a large knurled thimble that you screw onto the shock first. Then once that's all in and fully sealed, there is a smaller thimble that you screw-in next - that pokes a nib to open the valve. You unscrew the thimbles in reverse order to detach the pump. I can hear the air coming out of the pump, but that's a minuscule sparrows-fart compared to my old pump.

Pros and cons about the Giant pump...
Pros - good build quality and the pump handle is comfortable (large and round), and believe it or not - it goes all the way up to 400psi (I guess for the newer higher pressure shock designs).
Cons - the high capacity dial vernier markings (smaller and closer together) makes it harder to accurately place the needle for pressures under 100psi (common pressures for front forks). It's also on the big side as far as size is concerned, so not exactly something I'd bring on the trail with me.

But hey, I'm not complaining... best pump I've got to date. Takes away the stress and drama when removing the pump - and I know for sure that the pressure in the shock is precise and more importantly, repeatable. I believe there are other shock brands with a similar two-stage connector... but what can I say, I'm a Giant fanboi.

 

[Beekeeper]

You know my old pump looks similar to your pump @Beekeeper and I get the same problem. If I don't time it right and twirl it out fast enough, a considerable amount of air from the shock rushes out. And it's not just the air coming from the pump gauge and hose. The screw connector of the pump presses the valve as it goes in, but when unscrewed - air can escape through the threads before the connector 'nib' can back off far enough for the shock valve to be closed beforehand. If I'm slow, as much as half the air pressure I pumped in can escape.

The newer pumps, like the Rockshox pump has a rubber sleeve that seals around the threads before it pushes the valve open, and so when the pump screw connector is being withdrawn, this rubber sleeve keeps the threads sealed until the valve is fully closed. Simple but effective.

I just bought a GIANT shock pump that has a two stage connector (like what Zimmerframe mentioned early on). There is a large knurled thimble that you screw onto the shock first. Then once that's all in and fully sealed, there is a smaller thimble that you screw-in next - that pokes a nib to open the valve. You unscrew the thimbles in reverse order to detach the pump. I can hear the air coming out of the pump, but that's a minuscule sparrows-fart compared to my old pump.

Pros and cons about the Giant pump...
Pros - good build quality and the pump handle is comfortable (large and round), and believe it or not - it goes all the way up to 400psi (I guess for the newer higher pressure shock designs).
Cons - the high capacity dial vernier markings (smaller and closer together) makes it harder to accurately place the needle for pressures under 100psi (common pressures for front forks). It's also on the big side as far as size is concerned, so not exactly something I'd bring on the trail with me.

But hey, I'm not complaining... best pump I've got to date. Takes away the stress and drama when removing the pump - and I know for sure that the pressure in the shock is precise and more importantly, repeatable. I believe there are other shock brands with a similar two-stage connector... but what can I say, I'm a Giant fanboi.

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All very informative. I bought my cheap bike hut shock pump even before I bought my bike and assumed they were all the same. The rockshox pump was twice the price so I got the cheaper one. I guess even with shock pumps you get what you pay for.