| T.R | Title | User | Personal
Name | Date | Lines |
|---|
| 523.1 | Other differences are second order to this... | MENTOR::REG | It was 20 years ago next May | Wed Jan 20 1988 13:58 | 5 |
|
Kevlar is non magnetic, i.e. unaffected by the earth's magnetic
field. This could make a significant difference to directional
stability (better).
|
| 523.2 | -< A difference of opinion...>- | FSTRCK::PICKETT | | Wed Jan 20 1988 20:02 | 10 |
| Kevlar is a composite material that is used in the bead of the tire
only. It is used because it is lighter and much stronger than steel
and can be folded. It has nothing to do with directional stability
or magnetic fields as it is not used in or under the tread of the
tire. It is more of an evolutionary step-like going from steel rims
to alloys.
|
| 523.3 | Get 2 steel, 1 Kevlar... | RAINBO::WASSER | John A. Wasser | Thu Jan 21 1988 13:46 | 22 |
| > what is the difference between Kevlar and steel in the tires?
You don't say whether you are talking about
beads (the edge of the tire that holds it on the rim)
or
belts (the material under the tread that resists punctures).
Steel and Kevlar have been used for both. If the tire doesn't
say, they are probably talking about the bead. The only
difference in any case is that a Kevlar bead makes the
tire easier to fold but more expensive. When you see
a tire advertised as "Folding" it has a Kevlar bead.
Why would you want a folding tire? To carry as a spare in
case of a major cut in one of your running tires.
Why would you want a tire with steel or Kevlar belts? To
reduce the number of flat tires you have to deal with.
My advice: Get steel beaded tires for your bike and if you
are doing any major touring, get ONE Kevlar beaded folding
tire for you tool kit. Get belted tires at your option.
|
| 523.4 | quick and easy pit stop | WCSM::BUCHANAN | Mike Buchanan, Mt. View, CA | Thu Jan 21 1988 15:11 | 2 |
| I also find the folding tires much easier to deal with, that is getting
them on and off the rim.
|
| 523.5 | Kevlar = steel at 1/5 weight | EUCLID::PAULHUS | Chris @ MLO 8-3/T13 dtn 223-6871 | Thu Jan 21 1988 15:54 | 8 |
| A second to John's comments. For the record, Kevlar is almost
exactly as strong as steel, size for size. The advantage is that
it weights 1/5 as much, size for size (ie. 1/5 the density). Also,
since it is spun in rather fine fibres, it is less apt to break
when bent on a tight radius. Hence it's 'foldability' when used
as a bead material. When used as a belt, it's advantage is mainly
in weight (critical here re. rotational moment of inertia).
- Chris
|
| 523.6 | Anyone seen a SPECTRA tire yet??? | SUSHI::KMACDONALD | Got any ICE you need climbed? | Fri Jan 22 1988 13:07 | 21 |
| > since it is spun in rather fine fibres, it is less apt to break
> when bent on a tight radius. Hence it's 'foldability' when used
> as a bead material. When used as a belt, it's advantage is mainly
And now for something completely different, and possibly unrelated
totally! While Kevlar is certainly more foldable than steel, it is not
as foldable as assorted other fibers. Kevlar cord has been used with
rock climbing protection devices as slings, however it turns out that
bending kevlar cord on a tight radius is VERY damaging to the fibers. A
recent issue of ROCK & ICE compared various types of cord under such
conditions as bending on tight radius, kevlar was a clear loser,
although it does have advantages in some areas. I suspect that for
applications such as tire beads, the above is not really too critical;
however the R & I article mentions a newly developed fiber by the brand
name of SPECTRA - they were included in the tests as well, and
out-performed Kevlar in all categories, some categories by phenomenal
margins. As I said before, this may not be relevant for bike tires, but
folks being folks, someone will undoubtedly come out with a
Spectra-based bike tire soon. You heard it here first ...
ken
|
| 523.7 | Spectra = good stuff | EUCLID::PAULHUS | Chris @ MLO 8-3/T13 dtn 223-6871 | Fri Jan 22 1988 17:13 | 6 |
| A guy from Allied (makers of Spectra) gave a presentation on
the stuff at the IHPVA Builders Workshop in Jan. of '86 at MIT.
The stuff looks to be great. They send out a promotional bullitin
on the stuff a couple of times a year. If anyone is interested,
let me know. - Chris
|
| 523.8 | Laugh, and the world thinks you're nuts | HPSVAX::MILLER | I Heart My Picture of a Dog | Tue Jan 26 1988 19:55 | 12 |
| > < Note 523.1 by MENTOR::REG "It was 20 years ago next May" >
> -< Other differences are second order to this... >-
>
>
> Kevlar is non magnetic, i.e. unaffected by the earth's magnetic
> field. This could make a significant difference to directional
> stability (better).
Doesn't ANYBODY appreciate this guy's humor but ME? If not,
I fear I'm REALLY in trouble!
=-=-=-=-g=-=-=-=
|
| 523.9 | I didn't want to mention it | DEBIT::FISHER | Holy DSRI, Batman! | Wed Jan 27 1988 08:56 | 2 |
| I didn't want to let it go to his head. But it does appear to have
gone over a few people's.
|
| 523.10 | Tell us, Reg | AMUN::CRITZ | Pavarotti loses 85 | Wed Jan 27 1988 10:59 | 7 |
| I mentioned in other replys that REG is quite funny. Not
funny looking, or funny acting, just funny.
Now if he'd just tell me what occurred 20 years ago
next May....
Scott (It's probably something funny)
|
| 523.11 | Jokes? | ARCHER::KLASMAN | | Wed Jan 27 1988 12:28 | 7 |
| < Note 523.10 by AMUN::CRITZ "Pavarotti loses 85" >
-< Tell us, Reg >-
Not knowing Reg, except from his entries here, I could only hope that he was
joking. I hope no one takes his jokes seriously.
Kevin
|
| 523.12 | It really screwed up my compass too | GLIVET::DOYLE | JD Doyle | Wed Jan 27 1988 13:08 | 4 |
|
...and I just installed fenders lined with magnets to counter
the earth's magnetic pull. Guess I'll take 'em off...
|
| 523.13 | Power to the people! | CCYLON::SCHULDT | Larry Schuldt - WA9TAH | Wed Jan 27 1988 14:14 | 5 |
| It seems to me that if you could just hook up your lighting system
to the tire bead, you could do without a generator... the bead passing
throught the earth's magnetic field would induce a current in it
which could be used to drive the lighting system!
;-)
|
| 523.14 | & Mt. W. doesn't lean when 300 of us ride up it either | MENTOR::REG | Not B-M-B '88 disqualified; ...YET ! | Thu Jan 28 1988 16:06 | 12 |
| re .8 & a few of the subsequent ones... reread the title to .1
My point is that the practical differences between kevlar and steel
are so trivial that you might as well start worrying about the effect
of the earth's magnetic field. IMHO (I_n M_y H_umble O_pinion)
there's far too much Techno_dweebie mentality these days around
bicycling, I prefer to ride. I acknowledge that Techno_dweebing
is a valid pastime for those who can't or don't want to ride, but
it belongs elsewhere.
Reg
|
| 523.15 | | XCELR8::DELORIEA | | Thu Jan 28 1988 19:01 | 3 |
|
GEE!!!!!!!!! Ask a simple question. ;-)
|
| 523.16 | Pocket protectors & slide-rule holsters? | DR::BLINN | He's not a real Doctor.. | Fri Jan 29 1988 14:28 | 3 |
| Techno-dweebing, eh? Reg, you break me up!
Tom
|
| 523.17 | Questions are Welcome (more than some answers) | VIKING::WASSER | John A. Wasser | Fri Jan 29 1988 16:15 | 22 |
| > differences between Kevlar and steel are so trivial
I would not consider foldability a trivial difference. The
difference is important to long-distance tourers who want
to carry a spare tire.
> I acknowledge that Techno_dweebing is a valid pastime for those who can't
> or don't want to ride, but it belongs elsewhere.
If I understand this it means that one person can't ask
questions about bicycles and ride... It also implies
that the question was inappropriate for this conference.
Neither could be further from the truth.
Your host,
John A. Wasser
P.S. Please, folks. If you are going to attempt sarcasm
in reply to a question, mark it with a :-) since your
tone of voice cannot be heard through the terminal and
you just cause confusion.
|