silca super pista: should wheel pressure show?

Hi,

I just got a (sort of) new silca super pista pump.
It came without a manual - but Silca, Italy have graciously
offered to send me one. (I have another thread here with that ordeal)

My question, while I wait for the manual - after some tweaking
with the presta valve I manage to pump it up.

However, neither the white nor red niddle at any point show me the air pressure
of the wheel i'm pumping.

I set the red needle to, say 45 PSI, and start pumping.
The white needle just jumps up and settles back to zero every stroke.
I pump until it "seems" right.

Is this how things should be or did I get a defective pump ?!

Thank you!
-Gill

gbgbgbgb wrote:

I just got a (sort of) new silca super pista pump.
It came without a manual - but Silca, Italy have graciously
offered to send me one. (I have another thread here with that ordeal)

My question, while I wait for the manual - after some tweaking
with the presta valve I manage to pump it up.

However, neither the white nor red niddle at any point show me the air pressure
of the wheel i'm pumping.

I set the red needle to, say 45 PSI, and start pumping.
The white needle just jumps up and settles back to zero every stroke.
I pump until it "seems" right.

Is this how things should be or did I get a defective pump ?!

The red needle is just a visual aid; you set that to the desired pressure,
and then pump until the white needle is coincides with the red.

If the tire is inflating, but the white needle stays at zero, you may have
a bad check valve.

Art Harris

wrote...
I just got a (sort of) new silca super pista pump.
It came without a manual - but Silca, Italy have graciously
offered to send me one. (I have another thread here with that ordeal)

How did you contact them? I couldn't find them anywhere on the web,
and my pump didn't come with a manual.

snip
neither the white nor red niddle at any point show me the air pressure
of the wheel i'm pumping.

I had the same problem after I disassembled my pump to lubricate
everything (although in my case the white needle would rise with the
pump, but not hold the pressure in the gauge). In my case the grease
I used in the pump shaft got pushed into the check valve, causing it
to be stuck open.

Take apart the check valve (it's in the module that contains the
gauge) - it's just a disk on a stick with a spring. Clean the parts,
lubricate it lightly with oil, and put it back together. Should solve
your problem.

Michael

(Michael) wrote in message . com...

How did you contact them? I couldn't find them anywhere on the web,
and my pump didn't come with a manual.

www.silcapompe.it

neither the white nor red niddle at any point show me the air pressure
of the wheel i'm pumping.


i'm not sure i explained myself properly.
let me try again:
so the red needle is just a marker for my convenience.
i set it to the desired pressure, and start pumping.
as i pump the white needle climbs up to a certain pressure
(depending on my thrust) and descends back to zero.
This repeats itself at every pumping action.
And judging by your responses - this should be the desired behaviour(?)

My question is:
How do i know when the tire has actualyl reached the desired PSI level?
I was hoping the pump would also show tire presure.
But i suppose it doesnt because the presta valve only opens
when pressure from the pumping action is apllied to it?

Thanks!
-Gill

In article ,
says...
(Michael) wrote in message . com...

How did you contact them? I couldn't find them anywhere on the web,
and my pump didn't come with a manual.

www.silcapompe.it

neither the white nor red niddle at any point show me the air pressure
of the wheel i'm pumping.


i'm not sure i explained myself properly.
let me try again:
so the red needle is just a marker for my convenience.
i set it to the desired pressure, and start pumping.
as i pump the white needle climbs up to a certain pressure
(depending on my thrust) and descends back to zero.
This repeats itself at every pumping action.
And judging by your responses - this should be the desired behaviour(?)

My question is:
How do i know when the tire has actualyl reached the desired PSI level?
I was hoping the pump would also show tire presure.
But i suppose it doesnt because the presta valve only opens
when pressure from the pumping action is apllied to it?

That is true, but unless your pump is leaking, the needle should hold
at the last pressure reached (or close to it, anyway) because of air
trapped in the hose between the tire valve and the check valve in the
pump cylinder. That's what mine does; the pressure indicating needle
gradually drops if I stop pumping, but it's slow enough that I don't
have a problem seeing the reading. The peak of the needle's movement
is approximately your tire pressure. If it drops off quickly, you
probably have a leaking check valve or a leaking connection.

--
Dave Kerber
Fight spam: remove the ns_ from the return address before replying!

REAL programmers write self-modifying code.

"David Kerber" wrote in message
...

In article ,
says...

i'm not sure i explained myself properly.
let me try again:
so the red needle is just a marker for my convenience.
i set it to the desired pressure, and start pumping.
as i pump the white needle climbs up to a certain pressure
(depending on my thrust) and descends back to zero.
This repeats itself at every pumping action.
And judging by your responses - this should be the desired behaviour(?)

My question is:
How do i know when the tire has actualyl reached the desired PSI level?
I was hoping the pump would also show tire presure.
But i suppose it doesnt because the presta valve only opens
when pressure from the pumping action is apllied to it?

That is true, but unless your pump is leaking, the needle should hold
at the last pressure reached (or close to it, anyway) because of air
trapped in the hose between the tire valve and the check valve in the
pump cylinder. That's what mine does; the pressure indicating needle
gradually drops if I stop pumping, but it's slow enough that I don't
have a problem seeing the reading. The peak of the needle's movement
is approximately your tire pressure. If it drops off quickly, you
probably have a leaking check valve or a leaking connection.

The pump is leaking somehow. Usually it's just around the valve stem.
Switching to tubes with smooth (non-threaded) valve stems might help, or you
might need a new pump head or O-ring. As David says, just look at the highest
reading before the leakdown starts. The tube itself isn't leaking, because of
the one-way Presta valve -- just the air in the pump and hose.

Matt O.

That is true, but unless your pump is leaking, the needle should hold
at the last pressure reached (or close to it, anyway) because of air
trapped in the hose between the tire valve and the check valve in the
pump cylinder. That's what mine does; the pressure indicating needle
gradually drops if I stop pumping, but it's slow enough that I don't
have a problem seeing the reading. The peak of the needle's movement
is approximately your tire pressure. If it drops off quickly, you
probably have a leaking check valve or a leaking connection.

The pump is leaking somehow. Usually it's just around the valve stem.
Switching to tubes with smooth (non-threaded) valve stems might help, or you
might need a new pump head or O-ring. As David says, just look at the highest
reading before the leakdown starts. The tube itself isn't leaking, because of
the one-way Presta valve -- just the air in the pump and hose.

Matt O.

Thanks for both clarifications.
Seems to me that my pump is leaking because the needle does drop
very rapidly. It also seems that I can tip it to any "height" I want
by just stroking harder, so I guess you both mean read the needle as
you
apply measured pumping strokes.

Now, I am left wnodering whether the rapid drop is not to blame on my
ignorance.
I have just recently figured out how to handle the presta valve itself
-
ie, to loosen it so it releases air upon slight tapping on head before
inserting into pump head.
Now I'm thinking maybe im not placing the pump head properly on the
valve.
I do seem to struggle a lot with the pump head before it is resting in
a position that is both not leaking air from the wheel and allowing
for pumping.
I'll have another look in the morning.

"gbgbgbgb" wrote in message
om...

Thanks for both clarifications.
Seems to me that my pump is leaking because the needle does drop
very rapidly. It also seems that I can tip it to any "height" I want
by just stroking harder, so I guess you both mean read the needle as
you
apply measured pumping strokes.

Yes, as you come to the end of the stroke, the reading will peak, and then fall
as the air leaks out of the pump.

Now, I am left wnodering whether the rapid drop is not to blame on my
ignorance.
I have just recently figured out how to handle the presta valve itself
-
ie, to loosen it so it releases air upon slight tapping on head before
inserting into pump head.

Yes, they tend to stick unless you loosen them this way first. I don't know
why.

If everything's working properly, you can feel the pressure build inside the
pump, and then lessen as the valve opens and the air rushes into the tube.

Now I'm thinking maybe im not placing the pump head properly on the
valve.
I do seem to struggle a lot with the pump head before it is resting in
a position that is both not leaking air from the wheel and allowing
for pumping.

Smooth (non-threaded) valve stems help here. Look for Continental and Michelin
tubes, which have smooth stems.

Matt O.

Now I'm thinking maybe im not placing the pump head properly on the
valve.
I do seem to struggle a lot with the pump head before it is resting in
a position that is both not leaking air from the wheel and allowing
for pumping.


Hey, today I managed to battle the pump head into place - on both wheels.
And then I finally got the desired behaviour you were describing - needle was
practically standing in place at given pressure.
I guess I learned how to place the head thing, although I am not
quite sure what the trick was.
Either way - lots of thanks you guys!!!

Smooth (non-threaded) valve stems help here. Look for Continental and Michelin
tubes, which have smooth stems.


I suppose you mean after I've done this tube in?
I'll remember to enquire about that next visit to my LBS.

Thanks again!
-Gill

"gbgbgbgb" wrote in message
om...
Now I'm thinking maybe im not placing the pump head properly on the
valve.
I do seem to struggle a lot with the pump head before it is resting in
a position that is both not leaking air from the wheel and allowing
for pumping.


Hey, today I managed to battle the pump head into place - on both wheels.
And then I finally got the desired behaviour you were describing - needle
was
practically standing in place at given pressure.
I guess I learned how to place the head thing, although I am not
quite sure what the trick was.
Either way - lots of thanks you guys!!!

Smooth (non-threaded) valve stems help here. Look for Continental and
Michelin
tubes, which have smooth stems.


I suppose you mean after I've done this tube in?
I'll remember to enquire about that next visit to my LBS.

Thanks again!
-Gill

This of course raises the question of what is wrong with Schrader type
valves. Looking at the construction I guess they would easily handle
120psi - and are used on heavy trucks at high pressures.

I've always been a presta user myself - but except for weight and status -
why?
Hugh Fenton