More problems with Presta valves

In article <iI1db.597225$uu5.97946@sccrnsc04>, [email hidden] says...

Quoted message said:

I got a lot of good advice from you guys about Prestas earlier. Now a new prob has developed. When
I unclamp the pump and attempt to remove it from the thredded Presta valve it almost always hangs
up and I have to wiggle it (some times a little too vigorously) to remove it from the valve. Now I
think I have bent the valve core (???). When I went to my dealer this morning I was told that I
can't replace the core...I have to replace the entire inner tube. Is this true? What do you think
of replacing Prestas with Shraders? Is there some value to Prestas that I've missed? They seem
excessively touchy and troblesome.

Presta Valve cores being soft brass can get bent. This ususlly does not affect their ability to do
the job since you can not (AFAIK) bent the part of the core that seals the tube. If your tube is
still holding air satisfactorily, don't worry too much about it.

If you do bent the threaded part of the Presta core, you can straighten this with a pair of pliers.

Presta valves are skinnier than Schrader valves and can fit into narrow road style rims. while you
can drill out the rims to accommodate the wider diameter of a Schrader tube, doing so may compromise
the integrity of the narrow rim. (BTW I have done this on a not so narrow 19mm road rim with OK
results.).

If you have 622mm rims (AKA 700C), finding Schrader tubes to fit will be more of a chore than
keeping the Prestas and learning how to inflate.

BTW what pump are you using to pump air into these tubes?

Also, "All the cool bikers use Presta". ;-)

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

In the good old days of Silca pumps you would clench the brass chuck and hit your hand with the palm
of your other hand to dislodge the pump head. I do pretty much the same thing with my floor pump.
except I give a smart push to the pump head with my thumbs and have my fingers pushing against the
rim. Even if you bend the the little threaded shaft that goes through the lock a little, as long as
you can still close the lock, the valve is O.K. I haven't replaced the core, but I think if you can
unscrew it, you could replace it with a core savaged from on old trashed tube. After all, all the
bits were assembled by someone to make the valve, and no welding or epoxy is involved. Don't forget,
Presta valves have been in use for at least a century.

"pjclarkesq" <[email hidden]> wrote in message news:iI1db.597225$uu5.97946@sccrnsc04...

Quoted message said:

I got a lot of good advice from you guys about Prestas earlier. Now a new prob has developed. When
I unclamp the pump and attempt to remove it from the thredded Presta valve it almost always hangs
up and I have to wiggle

it

Quoted message said:

(some times a little too vigorously) to remove it from the valve. Now I think I have bent the
valve core (???). When I went to my dealer this morning I was told that I can't replace the
core...I have to replace the entire inner tube. Is this true? What do you think of replacing
Prestas with Shraders? Is there some value to Prestas that I've missed? They seem excessively
touchy and troblesome.

Phil

I have several adaptors (?) that I screw on top of the fitting once I have loosened the valve and I
clamp the pump onto that adaptor which has a ringed edge to it. Is that how you guys do it? When I
screw that adaptor that on top of the fitting there is so no metal contact with the valve; it is
impossible to bend it damage it (just the pressure of the air entering).

I have no idea anymore what you guys in the US have re adaptors, but I imagine you probably have the
same as we do. I never use the plastic pump that comes mounted on the frame of the bike as they are
difficult to pump without moving the entire valve assemply and casue damage the inner tube. Other
than that, I can't add anything useful to this discussion.

In message <[email hidden]>, DH <[email hidden]> writes

Quoted message said:

I have several adaptors (?) that I screw on top of the fitting once I have loosened the valve and I
clamp the pump onto that adaptor which has a ringed edge to it. Is that how you guys do it? When I
screw that adaptor that on top of the fitting there is so no metal contact with the valve; it is
impossible to bend it damage it (just the pressure of the air entering).

On my SKS track pump I used to use a push on adapter, to which the pump head clamped. I recently
replaced this head with a Topeak Smarthead - this works really well. you don't need to use any
adapters for Shraeder or Presta valves it fits both. It clamps firmly, but is easy to fit and remove
without straining the valve.

Quoted message said:

I have no idea anymore what you guys in the US have re adaptors, but I imagine you probably have
the same as we do.

This is in the UK.

Quoted message said:

I never use the plastic pump that comes mounted on the frame of the bike as they are difficult to
pump without moving the entire valve assemply and casue damage the inner tube.

For on the road etc. I use a normal pump, usually a Zefal HPX. Fort a direct fit pump this works
very well, and as long as you hold the head to stop to much movement it works fine. But once clamped
on it doesn't come of easily, rather than wiggle and cause problems I find a hit on the head end of
the pump with the heel of the hand works well at dislodging it .
--
Chris French

"pjclarkesq" <[email hidden]> wrote in message news:iI1db.597225$uu5.97946@sccrnsc04...
<snip> What do you think of replacing Prestas

Quoted message said:

with Shraders? Is there some value to Prestas that I've missed? They seem excessively touchy and
troblesome.

I think going with a Schrader valve is a good choice if you are using rims that are wide enough and
running lower pressure non racing tires. This would probably be the case for most recumbents. The
presta valve is wimpy (invented by the French I imagine) with the Schrader valve being the far more
robust of the two. Schraders are essentially trouble free (proven by millions on millions of miles
in automotive applications) and are in far more universal use. Prestas are almost exclusively used
on bicycles, especially those with skinny rims and ultra high pressure tires. Most of these guys
with this set up will look down their noses at Schrader valves so be fore warned.

skip

In message <[email hidden]>, harv <[email hidden]> writes

Quoted message said:

Even if you bend the the little threaded shaft that goes through the lock a little, as long as you
can still close the lock, the valve is O.K.

Even if you can't close the lock it still works fine, it's air pressure that keeps it closed
anyway. You can bend them back normally anyway. I wouldn't worry about it until I wa srepalcing the
tube anyway.

Quoted message said:

I haven't replaced the core, but I think if you can unscrew it, you could replace it with a core
savaged from on old trashed tube. After all, all the bits were assembled by someone to make the
valve, and no welding or epoxy is involved.

Not all things that have been assembled can be taken apart of course......

Some presta valves do have replaceable cores, I think I had a tube with one once, but I think they
are pretty uncommon though according to this site all Schwalbe tubes have removable cores.

<http://www.gearshift.co.uk/acatalog/Gearshift_Tubes_28.html>

I think if you can remove it you should see two small flats on the core where you fit a small
spanner to remove them. I've never tried to buy a valve core, though Vittoria list the cores :

<vittoria.comaccessories 2002.htmOpen ↗

Quoted message said:

And I'm pretty sure I've seen them on sale in the UK in some places, certainly they are listed on
web sites.
--
Chris French

In article <[email hidden]>, [email hidden] says...

Quoted message said:

I think going with a Schrader valve is a good choice if you are using rims that are wide enough
and running lower pressure non racing tires. This would probably be the case for most recumbents.

Probably not if this NG is any indication. Recent threads speak of 145
psi, etc. I would say anything over 80 is not low pressure. I have never had a low pressure tire on
any recumbent I've owned and I started out with no intention to become the speedster that I now
aspire to be.

Quoted message said:

The presta valve is wimpy (invented by the French I imagine)

My bets are that the Italians invented it and I'll keep that belief until proven otherwise.

Quoted message said:

with the Schrader valve being the far more robust of the two. Schraders are essentially trouble
free (proven by millions on millions of miles in automotive applications) and are in far more
universal use.

Actually I think these are about the same with a slight edge going to the Presta for holding air in
the tube under higeh pressure conditions. Schraders will leak because the only thing keeping it
closed is the spring. Prestas can leak if not seated properly, or a force greater than the air
pressure holding it closed is applied to open it.

Most of the time air leaks out of tubes from the porosity of the rubber not poor valves.

Quoted message said:

... Prestas are almost exclusively used on bicycles, especially those with skinny rims and ultra
high pressure tires. Most of these guys with this set up will look down their noses at Schrader
valves so be fore warned.

Quoting myself earlier in this thread: "Also, "All the cool bikers use Presta". ;-)"

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

"Cletus D. Lee" <[email hidden]> wrote in message
"]news:[email hidden]...

Quoted message said:

In article <[email hidden]>, [email hidden] says...

Quoted message said:

I think going with a Schrader valve is a good choice if you are using

rims

Quoted message said:

Quoted message said:

that are wide enough and running lower pressure non racing tires. This would probably be the
case for most recumbents.

Probably not if this NG is any indication. Recent threads speak of 145
psi, etc. I would say anything over 80 is not low pressure. I have never had a low pressure tire
on any recumbent I've owned and I started out with no intention to become the speedster that I
now aspire to be.

I know 100 to 125 psi is appropriate for Schrader valves. That's low pressure compared to 145 psi.
My bet is more recumbents run closer to 100 than 145 - especially those using the common 26" and 20"
tires and tubes. I remember reading somewhere that there can be an exploding problem up around
the145 psi. point.

Quoted message said:

Quoted message said:

The presta valve is wimpy (invented by the French I imagine)

My bets are that the Italians invented it and I'll keep that belief until proven otherwise.

I'm thinking if the Italians had invented Presta valves they would have made

belief until proven otherwise. My imagination is hardly ever wrong.

Quoted message said:

Quoted message said:

with the Schrader valve being the far more robust of the two. Schraders are essentially trouble
free (proven

by

Quoted message said:

Quoted message said:

millions on millions of miles in automotive applications) and are in far more universal use.

Actually I think these are about the same with a slight edge going to the Presta for holding air
in the tube under higeh pressure conditions. Schraders will leak because the only thing keeping it
closed is the spring. Prestas can leak if not seated properly, or a force greater than the air
pressure holding it closed is applied to open it.

People post periodically, as pjclarkesq did here, about presta valves breaking and being
troublesome. Schraders are surely much less troublesome. I'll take you word on the leakage - I've
never timed it.

Quoted message said:

Most of the time air leaks out of tubes from the porosity of the rubber not poor valves.

Agree.

Quoted message said:

Quoted message said:

... Prestas are almost exclusively used on bicycles, especially those with skinny rims and ultra
high pressure tires. Most of these guys with this set up will look down their noses at Schrader

valves so

Quoted message said:

Quoted message said:

be fore warned.

Quoting myself earlier in this thread: "Also, "All the cool bikers use Presta". ;-)"

Fabrizio agrees.

skip

It's possible that you have the presta chuck adjusted too tight on the pump. Most pumps that I've
seen have an adjustable cap on the end, which when tightened, squeezes a rubber o-ring type thing
which adjusts the amount of grip on the valve stem. If it's too tight, it will be difficult to
remove from the stem. If it's too loose, the pump head will fall off the valve.

Is this the case?

Gene

"pjclarkesq" <[email hidden]> wrote in message news:iI1db.597225$uu5.97946@sccrnsc04...

Quoted message said:

I got a lot of good advice from you guys about Prestas earlier. Now a new prob has developed. When
I unclamp the pump and attempt to remove it from the thredded Presta valve it almost always hangs
up and I have to wiggle

it

Quoted message said:

(some times a little too vigorously) to remove it from the valve. Now I think I have bent the
valve core (???). When I went to my dealer this morning I was told that I can't replace the
core...I have to replace the entire inner tube. Is this true? What do you think of replacing
Prestas with Shraders? Is there some value to Prestas that I've missed? They seem excessively
touchy and troblesome.

Phil

Quoted post said:

Originally posted by Pjclarkesq
I got a lot of good advice from you guys about Prestas earlier. Now a new prob has developed. When I
unclamp the pump and attempt to remove it from the thredded Presta valve it almost always hangs up
and I have to wiggle it (some times a little too vigorously) to remove it from the valve. Now I
think I have bent the valve core (???). When I went to my dealer this morning I was told that I
can't replace the core...I have to replace the entire inner tube. Is this true? What do you think of
replacing Prestas with Shraders? Is there some value to Prestas that I've missed? They seem
excessively touchy and troblesome.

Phil

Phil,

I've used both. Unless I'm using a compressor, I find that it is a lot easier to fill a presta valve than a schrader (my home pump is an old Joe Blow, so new pumps might be easier). This is especially true for the smaller tires like the 20 inch (maybe 16) on the Linear Sonic I ride. Since I only carry a small pump these days, as opposed to the long frame pump from DF days, this makes even more difference when I get one of the rare flats on the road.

Mike

skip said:

I know 100 to 125 psi is appropriate for Schrader valves. That's low pressure compared to 145 psi.
My bet is more recumbents run closer to 100 than 145 - especially those using the common 26" and
20" tires and tubes.

Schrader valves are used on air shocks too, and some of those go up to 300 psi.

Ken Kobayashi [email hidden] solarwww.mtk.nao.ac.jppersonalOpen ↗