Kevlar Tyres

phil wrote:
What's the score with kevlar tyres?

Do any of you have an opinion on them, belts or beads.

1. Beads are for the anti puncture but can weight a bit more than
regular
2. Belts are good for folding, so if you're touring you can fold up a
spare tyre and take it with you.

What would be the best uses for both of these tyres?

Are they worth the extra money?

You've got the terms mixed up.

A kevlar bead makes a tyre foldable and reduces weight. They are sometimes
more expensive, and make the tyre floppy during fitting, but otherwise there
is no disadvantage. Some of the better tyres come only in a folding
version.

A kevlar belt adds a bit of stiffness* and weight* as well as a bit of
puncture resistance. It's not /very/ effective, so regard it just as a
bonus. For puncture resistance, choose by the thickness of the rubber tread
(and any special thick layer under the tread) regardless of whether it has a
kevlar belt or not.

* This is insigificant in cases when the belt is very thin, but then so is
the amount of extra puncture resistance.

~PB

Myra in Cambridge wrote:
As for kevlar belts, I thought that they are not very popular
nowadays? That is, I don't recall tires by people like Schwalbe saying
that they have kevlar belts; they use other technologies for puncture
resistance. Maybe other people are using kevlar belts still? (I've
pretty much gone over to Schwalbe tires exclusively, since they suit
my uses very well.)

A lot of tyre manufacturers still use kevlar belts. I think Schwalbe is
more intelligent!

~PB

What's the score with kevlar tyres?

Do any of you have an opinion on them, belts or beads.

1. Beads are for the anti puncture but can weight a bit more than regular

2. Belts are good for folding, so if you're touring you can fold up a
spare tyre and take it with you.

What would be the best uses for both of these tyres?

Are they worth the extra money?
Phil

phil said the following on 01/10/2008 16:56:

Do any of you have an opinion on them, belts or beads.

1. Beads are for the anti puncture but can weight a bit more than regular
2. Belts are good for folding, so if you're touring you can fold up a
spare tyre and take it with you.

I think you might be confused. Beads are for folding, belts are for
anti-puncture.

I have had tyres with kevlar bands in them, but TBH I didn't really get
many less punctures than without. Kevlar beads though are definitely
useful. The concept of storing a tyre in the round or overlapped
figure-8 seems very odd now - tyres should just fold up! Also, a kevlar
bead is lighter than a wire bead.

--
Paul Boyd
http://www.paul-boyd.co.uk/

"phil" wrote in message
...
What's the score with kevlar tyres?

Do any of you have an opinion on them, belts or beads.

1. Beads are for the anti puncture but can weight a bit more than regular

2. Belts are good for folding, so if you're touring you can fold up a
spare tyre and take it with you.


I think you mean the other way around.

What would be the best uses for both of these tyres?

Are they worth the extra money?

I'm unconvinced by kevlar belts as a punture-proofing. Kevlar may be good
at resisting cutting, but little sharp things can still work their way in
between the threads.

On Oct 1, 4:56 pm, phil wrote:
What's the score with kevlar tyres?

Do any of you have an opinion on them, belts or beads.

1. Beads are for the anti puncture but can weight a bit more than regular

2. Belts are good for folding, so if you're touring you can fold up a
spare tyre and take it with you.

What would be the best uses for both of these tyres?

Are they worth the extra money?
Phil

I'm open to correction, but I think you may have that the wrong way
around...

A kevlar belt protects against punctures. One of the layers of fabric
that makes up the carcass of the tyre is made from kevlar. These
layers are typically made of nylon and other similar materials. Keval
is, depending on weave, thickness etc, tough and resistant to "stabs"
from glass etc.

Kevlar beads replace the standard steel wire beads around the tyre.
These beads "lock" into the edges of the rim as the tube is
inflated.
In this case, the kevlar is nominally lighter than the steel wire it
replaces, and because the kevlar is more like string than the wire,
the tyre can be folded up tightly without the bead "kinking" as would
be the case with steel.
However, because the kevlar bead stretches a bit more than the steel
wire, some kevlar beaded tyres are made fractionally tighter than the
steel beaded equivalents. This is not universal to all kevlar beaded
tyres though - there are specific combinations of rim and tyre that
are hard to fit.

HTH,

bookieb.

phil wrote:
What's the score with kevlar tyres?

Do any of you have an opinion on them, belts or beads.

1. Beads are for the anti puncture but can weight a bit more than regular

2. Belts are good for folding, so if you're touring you can fold up a
spare tyre and take it with you.

What would be the best uses for both of these tyres?

Are they worth the extra money?
Phil

I thyink you may have got this slightly backwards. Beads are good for
folding, and belts are for puncture resistance.

I think a kevlar bead is a good thing if you (a) need a folding tire,
say as an emergency tire on a long tour, or (b) want to reduce the
weight of your tires. For the vast majority of my uses, that is,
commuting or relaxed riding on lanes, neither is true, so I don't get
them.

As for kevlar belts, I thought that they are not very popular
nowadays? That is, I don't recall tires by people like Schwalbe saying
that they have kevlar belts; they use other technologies for puncture
resistance. Maybe other people are using kevlar belts still? (I've
pretty much gone over to Schwalbe tires exclusively, since they suit
my uses very well.)

-Myra

Pete Biggs wrote:

Myra in Cambridge wrote:
As for kevlar belts, I thought that they are not very popular
nowadays? That is, I don't recall tires by people like Schwalbe saying
that they have kevlar belts; they use other technologies for puncture
resistance. Maybe other people are using kevlar belts still? (I've
pretty much gone over to Schwalbe tires exclusively, since they suit
my uses very well.)

A lot of tyre manufacturers still use kevlar belts. I think Schwalbe is
more intelligent!

Schwalbe use kevlar belts in their standard Marathons. The Marathon
Racer doesn't and has less protection as a result.

This is from the Schwalbe technical guide:

Almost all SCHWALBE tires have a puncture protection
belt, though we purposely decided not to include them in
the special light and sports tires.
Even our standard tires are equipped with an effective
puncture protection belt made of natural rubber
(Puncture protection). MARATHON-tires, with the
proven combination of natural rubber and Kevlar fibers in the
Kevlar®-MB-Belt ensures remarkably high puncture
protection. Furthermore, our top of the range tires have
highly efficient puncture protection systems which are
specifically adapted to the particular requirements, for
example Double-Defense® or SmartGuard®.

The current state of the art is our SmartGuard®, the safest
puncture protection belt on the market.
Other puncture protection systems like Double-Defense®
or Kevlar®-MB-Belts provide a very high degree of
puncture protection. The decisive advantage of the
SmartGuard® is its effectiveness against objects that
become embedded in the tread, that are rolled over at
each turn of the wheel and will eventually perforate
virtually any protection belt. When this happens, the
thickness of the SmartGuard® proves its advantage as
a drawing pin will simply remain stuck in the rubber
without further harming the tire.
--
Phil Cook looking north over the park to the "Westminster Gasworks"

Quoting Myra in Cambridge :
I think a kevlar bead is a good thing if you (a) need a folding tire,
say as an emergency tire on a long tour, or (b) want to reduce the
weight of your tires. For the vast majority of my uses, that is,
commuting or relaxed riding on lanes, neither is true, so I don't get
them.

Not that folding tyres aren't very jolly, but a steel-bead tyre in the
folded figure-8 configuration doesn't really take up more space on tour -
on tour, you have enough other gear to pack the space inside it full.
--
David Damerell flcl?
Today is First Stilday, September - a weekend.