Silvio AIr Shock to retain pressure

[John Tolhurst]

Does anybody else out there have a problem with the air shock on their Silvio? Most of the time by shock will lose pressure at the beginning of a ride, and the boot that covers it is flat, or almost flat, during normal riding on smooth roads. I have always had trouble getting the right amount of pressure into it, as a certain amount of pressure is lost while removing the pump (unscrewing it.) It seems to be only a very little bit of loss. I pump it to about 185 psi hoping to get 180 psi after removal of the pump hose. It seems fine when compress the shock while standing over the bike with the front break on, but after the first dip in the road while riding it looks almost flat. Any thoughts? I've had the bike a year now, and I have always had this problem, about 70% or more of the time.

 

[John Dorlon]

It sounds like you got a

It sounds like you got a leaky one. Mine keeps pressure for about a month, and I know John T. has said that's about how often he checks his pressure.

 

[defjack]

    Have you replaced the

Have you replaced the valve core thats where mine was leaking. Jack

 

[Doug Burton]

The fork uses a Schrader valve...

... just like car tires and many bike tire inner tubes.

Most of us air-up tires before every ride. A similar argument could be made for the Silvio fork.

If the valve is dirty, or not screwed into the valve body all the way, it'll leak down pretty quickly.

Your local auto parts store will probably have a Schrader valve tool, which will make it easier to remove the valve core. Unscrew the valve core and wipe it off to remove any road detritus. A touch of light oil on the valve core will help it seat tightly when re-installed.

I have examined a few forks that were returned to us because they wouldn't hold air. I have yet to find one that was leaking anywhere other than the valve core.

Best,

Doug

 

[Doug Burton]

A little more info...

This is a Schrader valve core:

The red gasket is the valve operating seal. The air pressure in the fork actually helps this gasket to seal. These usually only leak badly if they get road dirt in them. Some loss of pressure over time is unavoidable, just as with your tires.

The black gasket seals the valve core to the outer pipe that the cap screws on to. If the valve is under or over-tightened on installation, this gasket can be distorted and seal poorly. You can see a little divot in the one in the picture if you look closely. This is where most of the leaks I've seen have come from. Very light lubrication (even water will do) helps this gasket "get friendly" with the seating surface and create a better seal. Avoid agressive chemical lubricants (lighter fluid or petroleum) as these can attack the gasket, as can silicone, as the gasket is usually silicone rubber. Vegetable oil can work fine, 3-in-1 is okay; motor oil contains additives that might not help. A very light glaze is all you want.

Cheers,

Doug

 

[TimOz]

I bet you are simply losing

I bet you are simply losing too much air out of the shock when pumping it up.

What shock pump are you using?
The Kind brand pump that was supplied with my bike has a very specific procedure that must be used so not to lose pressure. It is different to pumping up a tyre and I have seen some experienced Cruzbikers who did not do this right. I bet most people think it is like a tyre pump and you screw it on, pump and then screw it off.

It should go like this:
1. The shock pump consists of the pump body, dial gauge, flexible black tune and the black alloy fitting that you screw onto the schrader valve stem. It is not obvious that the black fitting is actually threaded onto the flexible tube of the pump and this is very important. It winds in and out.

2. Screw the Kind pump onto the schrader valve and pump it up to the desired pressure.

3. Hold the black fitting on the end of the Kind pump steady (ie locked on position on the valve stem) and unwind the entire pump counterclockwise. This backs the pump off the schrader valve sealing pin and lets it seal in the pressure you have chosen. It will expose about 8mm of thread.

4. Now keep unwinding the pump and the black fitting will unscrew off the schrader fitting. you will hear a small hiss of the pressure in the tube releasing. If you don't back the pump tube out of the black fitting and just wind it off like a tyre pump you will hear a much larger hiss and this is mist of the pressure in the shock escaping before the schrader valve seals.

I also found that I needed to adjust the pressure of my shock every week or so when the bike was new but it holds pressure much better now. I guess it was "bedding in" or something. I now need to adjust it every 4-6 weeks or so and just by a little.

Hope that works for you.

 

[Rick Newton]

Thanks guys

Thank you jdorlon, Doug, TimOz, and defjack. Your replies are very descriptive and helpful. Tim, I had noticed that the black alloy fitting screws in & out at the hose, and I suspected there was a technique to be followed. So I had tried various methods of release from the valve stem. I will make sure I follow yours to the tee. If that doesn't solve the problem, I will remove the valve core per Dougs comments.
Thanks again!

 

[Rick Newton]

Thanks guys

Thank you jdorlon, Doug, TimOz, and defjack. Your replies are very descriptive and helpful. Tim, I had noticed that the black alloy fitting screws in & out at the hose, and I suspected there was a technique to be followed. So I had tried various methods of release from the valve stem. I will make sure I follow yours to the tee. If that doesn't solve the problem, I will remove the valve core per Dougs comments.
Thanks again!

 

[Doug Burton]

Please have a read:

http://www.cruzbike.com/KindShockPumpOperation.pdf

 

[Rick Newton]

Front Suspension Adjustment using the KindShock Pump

Thanks Doug!

 

[TimOz]

Rick,
Did that shock pump

Rick,
Did that shock pump procedure work for you?
Curious.

 

[Rick Newton]

RICK, DID THAT SHOCK PUMP

I haven't ridden it since I tried it. Following the instructions, still a little bit of air leaked out. But it seems solid while standing over the handle bars and pressing down with the front brake on. I have to wait until I ride and go over a swale in the road to compress the shock fully. Thanks for checking Tim.

 

[Rick Newton]

RICK, DID THAT SHOCK PUMP

TimOz,
Yes, it did work for me. But sometimes I think my suspension sticks in the compressed position, or it leaks air over a period of a few days. I will keep monitoring the situation, this time checking pressure before each ride.