Need help with Presta Valves

Easy....when you first open the valve and attach the pump, before you attach the pump head gently
depress the vlave to let a little air escape and "unseat" the oring that holds the pressure on the
valve. Schraeder valves automatically do this but the presta's are more tempremental. Try that....

"pjclarkesq" <[email hidden]> wrote in message news:ZiFab.386369$cF.118354@rwcrnsc53...

Quoted message said:

My new Tour Easy came with Presta valves which I had never seen before. (Call me Luddite). I
subsequently discovered that my pump works with both Presta and Schrader valves but I couldn't
make it work with the Presta. After a two minute "Valve stems for dummies" class at my local
dealer (who also tested my pump) I came home and tried it. However, I still have problems.

One: when I attach my pump (which has a pressure gauge built in) it initially registers no
pressure. After the first "pump" the gauge

registers

Quoted message said:

about 60 after the 2nd "pump" it registers close to 100....which is what

the

Quoted message said:

dealer recommends. But this gives me a crisis in confidence. How can I tell what the real pressure
is when I get these 3 disparate readings?

When I get the reading of 100 I remove the pump from the stem at which

time

Quoted message said:

I hear a burst of air escape just like it does with the Schrader valve on

my

Quoted message said:

old upright. Could that burst of air be dropping the pressure from 100 to 60 (the first reading I
get when I start to pump next time)? Or am I just not getting accurate readings?

Can anyone help this puzzled dummy with some clarification? Or direct me

to

Quoted message said:

some place where I can find some info about how Presta's work?

"pjclarkesq" <[email hidden]> wrote in message news:ZiFab.386369$cF.118354@rwcrnsc53...

Quoted message said:

My new Tour Easy came with Presta valves which I had never seen before. (Call me Luddite). I
subsequently discovered that my pump works with both Presta and Schrader valves but I couldn't
make it work with the Presta. After a two minute "Valve stems for dummies" class at my local
dealer (who also tested my pump) I came home and tried it. However, I still have problems.

One: when I attach my pump (which has a pressure gauge built in) it initially registers no
pressure. After the first "pump" the gauge

registers

Quoted message said:

about 60 after the 2nd "pump" it registers close to 100....which is what

the

Quoted message said:

dealer recommends. But this gives me a crisis in confidence. How can I tell what the real pressure
is when I get these 3 disparate readings?

When I get the reading of 100 I remove the pump from the stem at which

time

Quoted message said:

I hear a burst of air escape just like it does with the Schrader valve on

my

Quoted message said:

old upright. Could that burst of air be dropping the pressure from 100 to 60 (the first reading I
get when I start to pump next time)? Or am I just not getting accurate readings?

Can anyone help this puzzled dummy with some clarification? Or direct me

to

Quoted message said:

some place where I can find some info about how Presta's work?

I have this happen to me also...its just you dont have a good connection with your pump nozzle and
no air is getting in. Place the nozzle on the stem and if it happens, readjust it and maybe even try
to push it down more. Just keep messing with it until you feel air flowing more smoothly.

Presta 101: (refer to the diagrams in accompanying the Sheldon Brown Web Page)
sheldonbrown.comgloss p.htmlOpen ↗

Presta Valvea are held closed by air pressure in the tube _and_ the little knurled nut at the top of
the valve stem.

First you have to open the valve. (bet you already knew this eh?) Next, Air pressure (and sticky
little gremlins) now keep the valve shut. Depress the open valve stem to release the gremlins and a
little stale air. Attach the pump. Work the pump until the air inside the hose is equal to the aire
inside the tube. Pump one more stroke to put more air pressure in the hose. Now due to unequal
pressure, the valve stem will move away from the seat toward the lower pressure in the tube. This
will again equallize the pressure in the tube and the hose but the valve will stay open. Your gauge
should reflect this. At this point, with the Presta valve open, additional pump strokes will
increase air pressure in the closed system (hose and tube). When the desired air pressure is
reached, Add about 5 more pounds to the closed system. The presta valve is still open(unlike the
Schrader which is closed by a spring). Open the system (i.e. remove the nozzle from the valve). The
air inside the tube will try to equallize with the air outside the tube. This will force the valve
stem closed. Until this valve stem is closed, some air will escape . At this point, the valve is
held shut only because the pressure inside of the tube is higher than the air pressure outside of
the tube. Closed the valve by tightening the knurled knob at the top.

In article <ZiFab.386369$cF.118354@rwcrnsc53>, [email hidden] says...

Quoted message said:

My new Tour Easy came with Presta valves which I had never seen before. (Call me Luddite). I
subsequently discovered that my pump works with both Presta and Schrader valves but I couldn't
make it work with the Presta. After a two minute "Valve stems for dummies" class at my local
dealer (who also tested my pump) I came home and tried it. However, I still have problems.

One: when I attach my pump (which has a pressure gauge built in) it initially registers no
pressure. After the first "pump" the gauge registers about 60 after the 2nd "pump" it registers
close to 100....which is what the dealer recommends. But this gives me a crisis in confidence. How
can I tell what the real pressure is when I get these 3 disparate readings?

When I get the reading of 100 I remove the pump from the stem at which time I hear a burst of air
escape just like it does with the Schrader valve on my old upright. Could that burst of air be
dropping the pressure from 100 to 60 (the first reading I get when I start to pump next time)? Or
am I just not getting accurate readings?

Can anyone help this puzzled dummy with some clarification? Or direct me to some place where I can
find some info about how Presta's work?

--

Cletus D. Lee Bacchetta Giro Lightning Voyager clee.orgclee.orgOpen ↗
- Bellaire, TX USA -

Quoted post said:

Originally posted by Pjclarkesq
My new Tour Easy came with Presta valves which I had never seen before. (Call me Luddite). I
subsequently discovered that my pump works with both Presta and Schrader valves but I couldn't make
it work with the Presta. After a two minute "Valve stems for dummies" class at my local dealer (who
also tested my pump) I came home and tried it. However, I still have problems.

One: when I attach my pump (which has a pressure gauge built in) it initially registers no pressure.
After the first "pump" the gauge registers about 60 after the 2nd "pump" it registers close to
100....which is what the dealer recommends. But this gives me a crisis in confidence. How can I tell
what the real pressure is when I get these 3 disparate readings?

When I get the reading of 100 I remove the pump from the stem at which time I hear a burst of air
escape just like it does with the Schrader valve on my old upright. Could that burst of air be
dropping the pressure from 100 to 60 (the first reading I get when I start to pump next time)? Or am
I just not getting accurate readings?

Can anyone help this puzzled dummy with some clarification? Or direct me to some place where I can
find some info about how Presta's work?

:p

Quoted post said:

Originally posted by Pjclarkesq
My new Tour Easy came with Presta valves which I had never seen before. (Call me Luddite). I
subsequently discovered that my pump works with both Presta and Schrader valves but I couldn't make
it work with the Presta. After a two minute "Valve stems for dummies" class at my local dealer (who
also tested my pump) I came home and tried it. However, I still have problems.

One: when I attach my pump (which has a pressure gauge built in) it initially registers no pressure.
After the first "pump" the gauge registers about 60 after the 2nd "pump" it registers close to
100....which is what the dealer recommends. But this gives me a crisis in confidence. How can I tell
what the real pressure is when I get these 3 disparate readings?

When I get the reading of 100 I remove the pump from the stem at which time I hear a burst of air
escape just like it does with the Schrader valve on my old upright. Could that burst of air be
dropping the pressure from 100 to 60 (the first reading I get when I start to pump next time)? Or am
I just not getting accurate readings?

Can anyone help this puzzled dummy with some clarification? Or direct me to some place where I can
find some info about how Presta's work?

More tips for those new to Presta. Some of the Presta valves are especially ornery. You may have to
let quite a bit of air out of the tube or depress the valve quickly a couple of times to get it
unstuck enough to put air in with the pump. You will get used to the feel and sound of the valve
finally opening while you are pumping and accepting its first "breath". It usually takes a couple of
pumps to pressure the hose and finally open the valve.

You may accidently unscrew the entire valve stem while you are trying to just unscrew the lock nut
at the top. Don't panic. It happens sometimes. You just have to get a pair of needle-nose pliers to
tighten the stem back in. Notice the flat sides of the stem for applying the pliers. Do NOT put the
pliers on the round area with threads and do NOT use the pliers to tighten the lock nut.

Sometimes the lock nut wants to shred my fingers instead of open. A little piece of inner tube or
rubber band provides enough friction for a good grip. You could even use duct tape in the true
MacGyver tradition.

I am assuming you have rearranged your pump head configuration to fit the Presta valve otherwise you
would not even get the pump head on.

Good luck. Don

Quoted message said:

When I get the reading of 100 I remove the pump from the stem at which time I hear a burst of air
escape just like it does with the Schrader valve on my old upright. Could that burst of air be
dropping the pressure from 100 to 60 (the first reading I get when I start to pump next time)? Or
am I just not getting accurate readings?

I recently discovered that the gauge on my foot pump is innaccurate.

Off by about 7 pounds. I had been using it for 3 years with no problems. So you might get a pressure
gauge and double check. Also, once you get the prescribed amount of air pressure in your tires, give
them a squeeze with your thumb and finger. Its good to have that reference when your out on the road
and forgot to take a gauge.

One or two or three more bits of advice:
1. There is a tiny rod or spindle in the center of the Presta upon which the valve nut spins. If you
put your pump on too far, you can bend this little rod by mashing on the nut. You really don't
need to spin the nut completely to the top of the rod. It only needs to come awa from the valve
stem enough to let air pass between the nut and the valve opening.
2. AirLock or Slime Presta tubes don't have threads on the outside of the valve stem so they tend to
wander and it's easy to rip them right off an older tube when using the pump. You can get inserts
to fill the hole in your rim and steady the stem or you can just forget Slime and get real
threaded Prestas with lock nuts.
3. AirLock and Slime Presta valve nuts can dry up and stick solidly shut. Attempting to open them
can unscrew the entire valve assembly. That little [censored] will shoot ten feet into the weeds AND
spray Slime all over the place. You must have needlenose pliers to reassemble the thing, if you
can find the stem. I keep a spare stem insert in my patch kit.

david boise ID

I assume you figured it out OK? I've had a few bikes here that use the Presta valve. I honestly did
not know what they were called until now. My LBG (here in Holland) referred to them as French, I
believe, when I asked him many years ago. At any rate, I ruined a tire trying to figure out how to
get air into it when I first moved here many years ago. An expensive lesson which I have never
forgotten. (Boy, did I feel dumb.) I now carry a few adaptors with me at all times.