comments on this rim?

Sheldon Brown said:

For a long time I had the idea of making up a tube with 36
valves for use on one of these rims. That way you'd
eliminate the problem of having to actually look for the
valve, and maybe even rotate your wheel before you could
pump up your tire. I was hoping to use 18 schraders
alternting with 18 prestas so any pump would work
too...but it was too much work and I never managed to
accumulate enough screw-on valve stems...

Sheldon "No Follow Through" Brown +---------------------------------------------------
+

Photoshop?

--
Andy Morris

AndyAtJinkasDotFreeserve.Co.UK

Love this:
Put an end to Outlook Express's messy quotes
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Quoted message said:

DRS said:

Wouldn't use of rim tape be mandatory with such rims? I
notice none was used in the first picture. (The second I'm
not so sure about).

Chalo said:

It depends on the tube and pressure used. Snowbike tires
are often run at 5 psi with 2-3mm thick downhill or
motocross tubes, in which case rim tape might well be
unnecessary. Of course the rim holes would have to be well
chamfered lest they chafe the tube.

Bicycles with those rims came with a mylar band

--
Andrew Muzi www.yellowjersey.org Open every day since 1
April, 1971

"Rick Onanian" <[email hidden]> wrote

Quoted message said:

Why don't we have a nice valve that offers secure closure,
secure attachment, and quick release without pressure
loss? Something like an air hose QC (but rather smaller
and lighter) would be great!

What's wrong with presta?

Quoted message said:

"Rick Onanian" <[email hidden]> wrote

Quoted message said:

Why don't we have a nice valve that offers secure
closure, secure attachment, and quick release without
pressure loss? Something like an air hose QC (but rather
smaller and lighter) would be great!

Peter Cole said:

What's wrong with presta?

Attaching and releasing a nozzle to inflate it or a gauge to
check it always involves some air escaping (at least, for
me). Also, in my experience, they have been fragile. I
should have put "robust" on that wish list too.

Schraders don't spill like that, and are robust, but they're
relatively bulky for skinny-tire bike application. Some
common tools for schraders require you to contact at a perfectly-
held angle for their seals to engage the end of the valve
(others seal around the side of the valve too, much better).

Finally, neither has the nice QC-ness that I like in
pneumatic tool couplings, which is the main point I was
considering in the quote above.
--
Rick Onanian

"Rick Onanian" <[email hidden]> wrote in message
"]news:[email hidden]...

Quoted message said:

Quoted message said:

"Rick Onanian" <[email hidden]> wrote

Quoted message said:

Why don't we have a nice valve that offers secure
closure, secure attachment, and quick release without
pressure loss? Something like an air hose QC (but
rather smaller and lighter) would be great!

Peter Cole said:

What's wrong with presta?

Attaching and releasing a nozzle to inflate it or a gauge
to check it always involves some air escaping (at least,
for me). Also, in my experience, they have been fragile. I
should have put "robust" on that wish list too.

Presta valves don't release air when removing the chuck,
since the valve closes after each pump stroke, the air
you hear is coming from the hose, it being trapped
between the presta valve and the check valve at the other
end of the hose.

You usually have to release some air before pumping
because the valves tend to stick a bit, and to overcome
this sticking often means over-pressurizing the hose (and
gauge, if there is one), which can blow the hose
connection or the gauge.

It's much easier to learn the feel of a fully filled tire
that to mess around with gauges, +/- 10% doesn't have any
real effect, anyway. Pumping is something that really only
has to be done every week or two. If you're using 20 mm
tires at 165 psi, or latex tubes, it may be a more frequent
task, but those applications are very weight-conscious, and
it's hard to think of a valve that would beat a presta in
that regard.

Presta valves aren't very fragile. If they're failing
it's either a Q/C problem in manufacture or a pumping
technique issue.

Quoted message said:

Schraders don't spill like that, and are robust, but
they're relatively bulky for skinny-tire bike application.

The holes significantly weaken the rims, small holes are
much better.

Quoted message said:

Finally, neither has the nice QC-ness that I like in
pneumatic tool couplings, which is the main point I was
considering in the quote above.

I think such fittings would be unnecessarily bulky, heavy,
and complex, besides it's a solution looking for a problem.
Presta valves have withstood the test of time, they're
really a very elegant solution.

Peter Cole said:

Presta valves aren't very fragile. If they're failing
it's either a Q/C problem in manufacture or a pumping
technique issue.

It's all too easy to bend the shaft once the valve has been
unscrewed. Yes, that's poor technique, but I'd describe
something that breaks easily with poor technique as fragile,
especially when the alternative is not so vulnerable.
--
David Damerell <[email hidden]> Kill
the tomato!

"David Damerell" <[email hidden]> wrote in message
"]news:[email hidden]...

Quoted message said:

Peter Cole said:

Presta valves aren't very fragile. If they're failing
it's either a Q/C problem in manufacture or a pumping
technique issue.

It's all too easy to bend the shaft once the valve has
been unscrewed. Yes, that's poor technique, but I'd
describe something that breaks easily with poor technique
as fragile, especially when the alternative is not so
vulnerable.

Maybe it's a difference in the tubes we buy, but I find the
valves difficult to bend/break -- I've never bent/broke one.
If you leave the wheel mounted on the bike you can put some
force on the valve (working against the mass of the bike),
but I don't know how it's possible to put much force on the
valve with the wheel off unless your hand slips.

Peter Cole said:

"David Damerell" <[email hidden]> wrote
in message

Quoted message said:

Peter Cole said:

Presta valves aren't very fragile. If they're failing
it's either a Q/C problem in manufacture or a pumping
technique issue.

It's all too easy to bend the shaft once the valve has
been unscrewed. Yes, that's poor technique, but I'd
describe something that breaks easily with poor technique
as fragile, especially when the alternative is not so
vulnerable.

Maybe it's a difference in the tubes we buy, but I find
the valves difficult to bend/break -- I've never
bent/broke one.

I don't just mean the valve body, but the little nubbin on
the threaded shaft - if you're cack-handed, which I have
been known to be, you can easily use that nubbin to bend the
shaft badly.

Quoted message said:

bike), but I don't know how it's possible to put much force
on the valve with the wheel off unless your hand slips.

I don't normally take my wheels off to pump them - I do far
more weekly maintenance inflation than post-flat inflation.
--
David Damerell <[email hidden]> Kill
the tomato!

"David Damerell" <[email hidden]> wrote > Peter Cole

Quoted message said:

Quoted message said:

Maybe it's a difference in the tubes we buy, but I find
the valves

difficult

Quoted message said:

Quoted message said:

to bend/break -- I've never bent/broke one.

I don't just mean the valve body, but the little nubbin on
the threaded shaft - if you're cack-handed, which I have
been known to be, you can easily use that nubbin to bend
the shaft badly.

Oh, that. Yes, that does bend easily, but I don't think
I've ever bent one of those either, they just seem to stay
out of the way.

Quoted message said:

Quoted message said:

bike), but I don't know how it's possible to put much
force on the valve

with

Quoted message said:

Quoted message said:

the wheel off unless your hand slips.

I don't normally take my wheels off to pump them - I do
far more weekly maintenance inflation than post-flat
inflation.

Yeah, me too, but I use a floor pump for that, so it's hard
to tweak a valve with just a hose connection. It's harder to
use a frame pump with the wheel still on, I could see where
valves could get bent that way.

Peter Cole said:

"David Damerell" <[email hidden]> wrote >
Peter Cole

Quoted message said:

I don't just mean the valve body, but the little nubbin on
the threaded shaft - if you're cack-handed, which I have
been known to be, you can easily use that nubbin to bend
the shaft badly.

Oh, that. Yes, that does bend easily, but I don't think
I've ever bent one of those either, they just seem to stay
out of the way.

I don't anymore, but I used to before I worked out how not
to. I think it's reasonable to say that _in this respect_
the Presta valve is inferior, because other valves are
harder to break.
--
David Damerell <[email hidden]>
Distortion Field!