Air shocks losing pressure

[Legendary-dave]

I’m a new owner ...August ....I did my shocks straight away ( set the pressure for my height weight and riding terrain ) ....I’ve just checked them again and I’ve lost half on the front and nearly all on the back ....do you use the shock pump when they are open or closed ....have I made a rookie error or are they leaking air ...do they leak air , does the autum temperature play a factor ....any advice is welcome ..thanks

 

[Al Boneta]

I’m a new owner ...August ....I did my shocks straight away ( set the pressure for my height weight and riding terrain ) ....I’ve just checked them again and I’ve lost half on the front and nearly all on the back ....do you use the shock pump when they are open or closed ....have I made a rookie error or are they leaking air ...do they leak air , does the autum temperature play a factor ....any advice is welcome ..thanks

How long does it take for them to lose pressure? If the last time you aired them up was August, it’s not the shocks it’s you.

 

[Legendary-dave]

I’m not sure ...I’ll check it again later ....but on this occasion it would’ve been about 10 weeks between checks

 

[outerlimits]

I’m not sure ...I’ll check it again later ....but on this occasion it would’ve been about 10 weeks between checks

You might loose a little air say a few psi over that time, but not huge amounts like you say. If it’s loosing air that quickly then something is up with them.
Are we talking a new bike or used ?

 

[KenX]

If you'd lost almost all the air from the shock, the bike would be unrideable, for sure you'd notice it.
So you're probably losing air when you thread on the shock pump........
There's only a small volume of air in the shock and it doesn't take much to lose it

 

[Legendary-dave]

You might loose a little air say a few psi over that time, but not huge amounts like you say. If it’s loosing air that quickly then something is up with them.
Are we talking a new bike or used ?

 

[Legendary-dave]

It’s a new bike

 

[outerlimits]

It’s a new bike

If it is loosing that much air over 10 weeks then I’d take it back for warranty.

 

[slippery pete]

The valve cores can be loose. This has two effects. 1. You can have a gradual loss of pressure. 2. The valve core protrudes more and doesn't fully close before you remove the shock pump,

#2 is a really bad thing to have going on as you can't trust your shock/fork settings and they will jump around massively as you attach/detach the pump.

Proper behaviour is:

- no escaping air when you attach the shock pump (just a brief hiss as the hose pressurises)
- a brief hiss of air depressurising the hose when you remove the shock pump

If you can find any point in attaching/detaching the pump where the shock/fork depressurises ( extended hiss of escaping air) it is a problem that needs fixing. Start with nipping the valve cores tighter (Schrader valve core tool). Sometimes your shock pump seal can be deformed or just out of tolerance in which case you need to try a different shock pump. >90% of shock pumps are just fine (including the cheap ones).

Overtightening of the shock pump onto the valve can distort the seal. The adapter only needs a quarter turn after the hiss of equalising pressure into the hose.

 

[steve_sordy]

I've never done this, but the idea was prompted by this particular problem.

Connect the shock pump, so that you get a reading. Pump it up to a round figure if its easier. Then leave the shock pump connected and see how long it takes for the pressure to drop, as displayed on the dial.

If you have a big problem, I'm sure you'd notice a pressure drop overnight or after a few days if its a minor one.

PS: Apart from a faulty valve on a new shock, I have never had a problem like yours. They do depressurise over time, but such a long time that I don't bother checking on a frequent basis. If I check every 3-4 months that would be about right, but I don't have a schedule. I take my cues from how the bike rides.

 

[Legendary-dave]

If it is loosing that much air over 10 weeks then I’d take it back for warranty.

Thanks ?

 

[Al Boneta]

Occasionally a new fork or shock will leak out of the box, but it happening to both is really rare. Like mentioned above, check the valve cores to make sure they are not loose and are crewed in all the way.
As part of our prep routine when assembling new bikes, we remove the valve cores from the shock and lightly apply grease to the threads.
I use plumber’s tape on my personal bikes

 

[Legendary-dave]

Occasionally a new fork or shock will leak out of the box, but it happening to both is really rare. Like mentioned above, check the valve cores to make sure they are not loose and are crewed in all the way.
As part of our prep routine when assembling new bikes, we remove the valve cores from the shock and lightly apply grease to the threads.
I use plumber’s tape on my personal bikes

I’ve just got home and checked them both , they’ve both lost about 10 psi each but I’m not sure if that’s leakage out of the shock pump when I disconnect or something, it’s a cheaper end shock pump so I don’t know if that has anything to do with it or it’s something I’m doing wrong ...

 

[Al Boneta]

Some pumps will let out more air than others.10psi isn’t unheard of.

 

[Legendary-dave]

Some pumps will let out more air than others.10psi isn’t unheard of.

With use do they lose air and I’m not light ...196 lbs ....could this be a factor ...I ride with them on a lot even on roads ?

 

[Al Boneta]

Yes they will lose over time. I check my pressure every month

 

[Legendary-dave]

Yes they will lose over time. I check my pressure every month

Good to know and it has been a month since I last did anything with them ...I got the bike in August ( late )
Thanks for you info

 

[Zimmerframe]

I use Stans in mine to stop leaks ..

 

[Legendary-dave]

I use Stans in mine to stop leaks ..

What are stans?

 

[Zimmerframe]

Crap .... I've just given you a glimmer of hope ... Sorry, I must now cruelly swipe it away !

Sadly I was being stupid (which is normal - though I did just try a few days of serious...) .... Stan's no tubes ...

 

[HikerDave]

I’m a new owner ...August ....I did my shocks straight away ( set the pressure for my height weight and riding terrain ) ....I’ve just checked them again and I’ve lost half on the front and nearly all on the back ....do you use the shock pump when they are open or closed ....have I made a rookie error or are they leaking air ...do they leak air , does the autum temperature play a factor ....any advice is welcome ..thanks

Something seems seriously wrong. My rear Fox Factory DPS has a very slight leak out of the negative air chamber; total loss about 5-10 psi in a week but very noticeable when I push down on the saddle to match the equalization port; force required to hold the bike down rapidly decreases but I’m too lazy to try to fix it. Front fork has a larger volume so leaks insignificant.

You’ll definitely notice a pressure change when the weather turns cold but not enough to explain what you’re seeing; PV = uRT but the T in this case is based on absolute zero (-273C) so a fairly small percentage change for the change in weather.

 

[Legendary-dave]

Crap .... I've just given you a glimmer of hope ... Sorry, I must now cruelly swipe it away !

Sadly I was being stupid (which is normal - though I did just try a few days of serious...) .... Stan's no tubes ...

I’m going to find you and sing spandau ballet songs to you ..... all night ?

 

[outerlimits]

What are stans?

Ignore Zimmerframe,
You’ll get sucked into his vortex and struggle to climb out. Some say he’s full of piss and wind, some say he’s just a lonely old man with a walking frame, reliving his youth via the internet, some even think he’s funny and sometimes helpful. To most of us he’s “just Zimmer” ?

 

[Legendary-dave]

Ignore Zimmerframe,
You’ll get sucked into his vortex and struggle to climb out. Some say he’s full of piss and wind, some say he’s just a lonely old man with a walking frame, reliving his youth via the internet, some even think he’s funny and sometimes helpful. To most of us he’s “just Zimmer” ?

That’s ok ....it did make me go check them again and all is good ...they’ve stayed at the same psi as last night