Wire vs. kevlar beads
Dave Stallard
Perhaps there is a difference in price as well. But are there
differences in durability between the two?
Dave
bfd
carbon 12 SL model. Both are folding tires.
On my commuter/junk/costco special, I'm using an Avocet City and Cross
26x1.25 which has a wire bead. Another excellent rolling tire, that is
durable. Highly recommended and reasonably priced too!
Sheldon Brown
> Kevlar beads are surely lighter than wire,
Yes, usually saves 50 grams (2 oz.) per tire.
> and allow for foldability.
> Perhaps there is a difference in price as well. But are there
> differences in durability between the two?
Tire beads don't wear out nor break in normal service, so there's no
"durability" issue.
Wire bead tires are usually easier to mount, and in some cases more
resistant to blow off.
Sheldon "http://sheldonbrown.com/glossary" Brown
+-----------------------------------------------------+
| If one lets fear or hate or anger take possession |
| of the mind, they become self-forged chains. |
| --Helen Gahagan Douglas |
+-----------------------------------------------------+
Harris Cyclery, West Newton, Massachusetts
Phone 617-244-9772 FAX 617-244-1041
http://harriscyclery.com
Hard-to-find parts shipped Worldwide
http://captainbike.com http://sheldonbrown.com
carl...@comcast.net
<capt...@sheldonbrown.com> wrote:
[snip]
>Wire bead tires are usually easier to mount, and in some cases more
>resistant to blow off.
>
>Sheldon "http://sheldonbrown.com/glossary" Brown
Dear Sheldon,
I thought that I'd read claims that it was Kevlar bead tires
that were stretchier and easier to mount, not wire bead
tires, whose lack of stretchiness made them more resistant
to blow-off.
Am I just punch-drunk after the playoffs?
Dolefully,
Carl Fogel
do not spam
<carl...@comcast.net> wrote:
>I thought that I'd read claims that it was Kevlar bead tires
>that were stretchier and easier to mount
I've found that kevlar bead tires usually fit tighter and are
thus harder to mount than wire bead tires (at least when new).
They do loosen up some after you use them.
Alex Rodriguez
>
>
>Kevlar beads are surely lighter than wire, and allow for foldability.
>Perhaps there is a difference in price as well. But are there
>differences in durability between the two?
Not because of the bead. The bead has no bearing on tread wear. What does
tend to happen is that the tire companies will make their high end racing
tires with a kevlar bead. Since they are racing tires and they know most
racers are weight weenies, they want to make them very light. So they make
the tread on the tire very thin to keep the weight down. The tires with wire
beads tend to be the lower end tires where tread life is more important, so the
tread tends to be thicker.
-----------
Alex
Zog The Undeniable
No. IME kevlar beaded tyres can be really, really, hard to fit when
they're new - never had any real difficulties with steel beaded tyres.
Zog The Undeniable
> I've found that kevlar bead tires usually fit tighter and are
> thus harder to mount than wire bead tires (at least when new).
> They do loosen up some after you use them.
Agreed. After 2 weeks on the rim they're as easy to mount as steel
beads. I suspect that kevlar beads are made slightly undersize because
they are known to creep over time, and making them the precise 622mm or
whatever could lead to them blowing off at 150psi.
Kenneth
<hroth...@yahoo.com> wrote:
>After 2 weeks on the rim they're as easy to mount as steel
>beads.
Howdy,
I am happy to assume that you are correct, but I wonder:
Why would kevlar tires become easier to mount after a few weeks of
use? Once mounted, they are not being stretched at all it would seem.
Thanks for your thoughts,
--
Kenneth
If you email... Please remove the "SPAMLESS."
Dave Stallard
FWIW, my Kevlar-beaded Vittorias could be taken on and off like
slippers. But, I never had to put them on new - only after they had
considerable mileage.
Dave
gwhite
"No" on wear durability. For a given model, they are otherwise identical.
A kevlar beaded tire is lighter, nicely folds, and costs more. Wire beaded
tires can be used on hookless rims -- if there is such a thing anymore -- and I
suspect have a bit more resistance to blow off.
dianne_1234
Yes. I've seen several wire-beaded Continentals where the wire has
worn through the casing. I've never seen this happen with Kevlar
beads.
But the bead material has no effect on tread wear.
Phil, Squid-in-Training
> use? Once mounted, they are not being stretched at all it would seem.
The phenomenon known as creep is as follows:
------------------------------------------------
At room temperature, structural materials develop the full strain they will
exhibit as soon as a load is applied. This is not necessarily the case at
high temperatures (for example, stainless steel above 1000°F or zircaloy
above 500°F). At elevated temperatures and constant stress or load, many
materials continue to deform at a slow rate. This behavior is called creep.
At a constant stress and temperature, the rate of creep is approximately
constant for a long period of time. After this period of time and after a
certain amount of deformation, the rate of creep increases, and fracture
soon follows.
-------------------------------------------------
Since the bead on a bicycle tire does not experience increased stress, only
a load as a function of the tire pressure, the bead deforms to a stress that
does not make it creep further, so fracture/failure isn't an issue.
I've found this to be true on wire beads... I don't have too much experience
with kevlar bead tires.
--
Phil, Squid-in-Training
Qui si parla Campagnolo
foldability.
Perhaps there is a difference in price as well. But are there
If the same tire, no difference other than the bead. Sometimes tough to find
higher end tires in wire bead versions tho.
Peter Chisholm
Vecchio's Bicicletteria
1833 Pearl St.
Boulder, CO, 80302
(303)440-3535
http://www.vecchios.com
"Ruote convenzionali costruite eccezionalmente bene"
Werehatrack
>On Fri, 22 Oct 2004 14:23:42 -0400, Sheldon Brown
><capt...@sheldonbrown.com> wrote:
>
>[snip]
>
>>Wire bead tires are usually easier to mount, and in some cases more
>>resistant to blow off.
>>
>>Sheldon "http://sheldonbrown.com/glossary" Brown
>
>Dear Sheldon,
>
>I thought that I'd read claims that it was Kevlar bead tires
>that were stretchier and easier to mount, not wire bead
>tires, whose lack of stretchiness made them more resistant
>to blow-off.
This is a YMMV issue. *Some* Kevlar-bead tires get easier to mount
and dismount after they've been in service for a while, but some are a
royal pain from the very first...and stay that way. Wire-bead tires
may be anywhere in that spectrum as well, and it's been my experience
that sometimes a used wire-bead tire is easier to deal with than it
was when new; I think the loss of stiffness in the carcass that comes
with prolonged use of the cheapass tires I buy may be the factor in
that case.
>Am I just punch-drunk after the playoffs?
Yes, I had cause to celebrate the Astros' loss; it means we *won't*
have two weeks of additional lunacy to deal with around here.
--
Typoes are a feature, not a bug.
Some gardening required to reply via email.
Words processed in a facility that contains nuts.
Werehatrack
With Kevlar, it's my understanding that there may be some lengthening
of the bead associated with fiber alignment which occurs slowly after
a number of hours under inflation tension. The cord is embedded in
the rubber, and can't immediately shift to its final position, but
will do so gradually. Once it reaches that point, it doesn't shift
farther.
g.daniels
Panaracer Pasela Tg Road Tire 27x1-1/4
with kevlar bead-this is a road tire, right?
how does the bead and bead coating, bead and bead attachments to
carcass look for durability on this model?
when LBSing, check out the Conti TT bead, bead cover, bead
attachments, compare to Michelin...
g.daniels
carl...@comcast.net
Dear Werehatrack,
From what you and others say, I gather that how hard the
different tires are to mount on rims (and how hard it gets
after some mileage) varies from model to model more as much
as from Kevlar to wire.
As for more tragic matters, I just got off the phone. My
former sister called to gloat from Boston (and will do so
until after spring training), ostensibly unaware that
traffic here in Pueblo is at a standstill this morning
because her junior senator is visiting town (a librarian
warned me not to even try to pick up a book on hold this
morning).
Sullenly,
Carl Fogel
jobst....@stanfordalumni.org
>> Kevlar beads are surely lighter than wire, and allow for
>> foldability. Perhaps there is a difference in price as well. But
>> are there differences in durability between the two?
> If the same tire, no difference other than the bead. Sometimes tough
> to find higher end tires in wire bead versions tho.
Avocet ROAD 700-25 tires come in both versions and are otherwise
indistinguishable. I keep a folding one in my touring bag and have
had occasion to use it. I find wire bead tires more convenient to
change. There is no apparent difference in performance, that is, I
can't tell the difference other than the detail of the tire label.
Jobst Brandt
jobst....@stanfordalumni.org
Blair P. Houghton
durability?
Looking at fold-ups in the store, I see the edges cracked and
kinked every inch or so around the folds.
Good, bad, or irrelevant?
--Blair
"I got plenty of tires."
carl...@comcast.net
wrote:
Dear Blair,
I've wondered about that, too, but my fold-ups have always
mounted, inflated, and rolled without any problems--no beads
breaking, no sidewalls failing, nothing unusual.
I run 120-125 psi on 700c x 26, about 5,000 miles yearly,
around 220 pounds of rider and bicycle.
I rarely wear tires out in terms of tread loss. I replace
them when the holes in the tread from goatheads, glass and
rock chips, and mystery debris look bad enough to trap fresh
chips or even bulge.
I think that I used the same model in the slightly heavier,
cheaper wire-bead version and noticed nothing different when
I switched, but that was several years ago.
Carl Fogel