correct tube size?

Quoted message said:

why buy the "right" tube diameter when the next larger size provides
greater flat protection due to the rubber getting stretched less thin-
as buying a 38c not a 32c
or is this faulty logic?
or to ask another way-how much weight is saved and speed gained from a
38 to a 32?(x2)?

It can be difficult installing an oversized tube. Many people have enough
difficulty with one of the correct size, and don't understand that adding a
bit of air to the tube first actually makes the job easier.

In some cases, tubes are undersized to begin with, so going to something a
bit larger (indicated size) might be fine. But a truly too-large tube risks
being installed with rubber folded over itself in places, which can cause
flats due to abrasion.

--Mike Jacoubowsky
Chain Reaction Bicycles
www.ChainReaction.com
Redwood City & Los Altos, CA USA
<[email hidden]> wrote in message
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Quoted message said:

why buy the "right" tube diameter when the next larger size provides
greater flat protection due to the rubber getting stretched less thin-
as buying a 38c not a 32c
or is this faulty logic?
or to ask another way-how much weight is saved and speed gained from a
38 to a 32?(x2)?

"Mike Jacoubowsky" wrote: It can be difficult installing an oversized tube.
(clip)
^^^^^^^^^^^^^^^
Look at the post by [email hidden] in rec.bicycles.misc

In article
<[email hidden]
t>,

Leo Lichtman said:

"Mike Jacoubowsky" wrote: It can be difficult installing an oversized tube.
(clip)
^^^^^^^^^^^^^^^
Look at the post by [email hidden] in rec.bicycles.misc

Please supply the Message-ID header. e.g.

Message-ID: <[email hidden]>

--
Michael Press

Quoted message said:

why buy the "right" tube diameter when the next larger size provides
greater flat protection due to the rubber getting stretched less thin-
as buying a 38c not a 32c
or is this faulty logic?

It's faulty logic. First, if the next larger is really too large, it
may wrinkle and fail. Second, if it's really enough thicker to be
resistant to punctures, then it'll also be enough thicker to increase
rolling resistance by itself. Third, a *properly sized* tube isn't
stretched all that thin. Fourth, if you want a thick tube, they exist
and are sold as "thorn resistant" for many sizes of tire, but they
carry the same rolling resistance penalty mentioned above. Fifth,
mere marked size range isn't likely to be a good guide for what you're
trying to find; see comments below.

Quoted message said:

or to ask another way-how much weight is saved and speed gained from a
38 to a 32?(x2)?

Not much, but there's not a lot of difference there.

If you sample the various brands of tube, you will find that there are
many tubes marked as usable across that size range (and beyond), for
one thing. If you collected tubes and measured their wall thickness,
you would probably also discover that some brands (and samples within
brands) of nominally same-size units vary considerably in both initial
and installed thickness, so that the mere marked size range might not
be a reliable indicator of whether a given tube will achieve the
result that you're seeking.

--
Typoes are a feature, not a bug.
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datakoll said:

why buy the "right" tube diameter when the next larger size provides
greater flat protection due to the rubber getting stretched less thin-
as buying a 38c not a 32c
or is this faulty logic?

Yes, it is. Stretching a tube a few mm will not make it prone to flats,
but using a too-large tube makes it harder to get the thing inside the
tire without pinching the tube between tire and rim.

I was on a ride with a guy, rather clueless, who had just gotten thinner
tires for his bike. The shop re-used the old, big tubes, and it was
freaking impossible to get them inside. He had lots of explosive flats on
the ride, and I eventually sent him back home with both of my spare tubes.
Now, his was an extreme case; the tubes were for something like 38s and
he was using more like 28mm tires.

But in general, no advantage in using too-fat a tube, and serious
disadvantages.

--

David L. Johnson

__o | Do not worry about your difficulties in mathematics, I can
_`\(,_ | assure you that mine are all greater. -- A. Einstein
(_)/ (_) |

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Quoted message said:

why buy the "right" tube diameter when the next larger size provides
greater flat protection due to the rubber getting stretched less thin-
as buying a 38c not a 32c
or is this faulty logic?
or to ask another way-how much weight is saved and speed gained from a
38 to a 32?(x2)?

I'd been running 700x28 tires on my main bike, but while it was in the paint
shop, my backup bike had 700x23s. I got a flat (from a freakin' STAPLE), and
the spare I was carrying was marked 700x28-32. It went in , sorta, and it
got me the rest of the way to work, then to the shop to get a new 700x23
spare, then back home. The next time I took the bike out, I was about 5
miles out and the rear-end started feeling real squirrely. I stopped and
checked the pressure, which was fine. I got back on, rode about 100 feet and
had a blowout. The folded portions of the tube had all worn themselves very
thin, and although the hole was small enough to patch, there were 3 or 4
other spots that looked like they could go at any time, since the folds made
many weak spots.

Too small is better than too big. Just right is best.

sounds reasonable. i was using fiber filled self sealers and the fiber
was giving me gas getting stuck in the needle valve so i went to
walmart slimes which were GRRRRRRRRRRRRRRREATTT but 700c and 27"'s
aren't racked now so back to specialized after wal's regulars lasted
500 miles or less with longitudinal rubber failures.
wal now has a new supplier with a different look now installed

will two slime liners over one tube wrinkle the rubber past design
standards?