tire liners and mph
n...@none.comspam
for a given amount of effort when using tire liners?
26" atb, I weigh 205 lbs.
I got a flat from a thorn on the third time that I went offroad some years
ago. I subsequently put in a cheap set of liners (they're probably fairly
heavy) and have never had a flat since, but it seems to me that I am putting
out a lot more energy than others do to achieve a modicum speed.
richard byrnes
encounters less rolling resistance. But that's only my opinion. The ride
is a bit harsher with liners. I think the weight effects are negligible.
I use liners for the same reason: to cut down on flats.
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<n...@none.comspam> wrote in message news:3b06aab1...@news.epix.net...
David L. Johnson
If you are comparing your performance to someone on a road bike, on a flat
road, it's not the tire liners that are slowing you down, it's the bike. A
mountain bike can't maintain the same sort of road speed as a road bike; it's
heavier, and those tires have much more rolling resistance. You also can't
get in as good a riding position for road riding. Both your body and you bike
are providing too much air resistance.
Your lack of flats since the tire liners is probably as much due to chance as
any protection they provide. Imagine a thorn large enough to get through your
mountain-bike tire. How much longer does it have to be to get through the
liner? 1mm? Less? What about that liner actually stops anything?
--
David L. Johnson
__o | And though I have the gift of prophecy, and understand all
_`\(,_ | mysteries, and all knowledge; and though I have all faith, so
(_)/ (_) | that I could remove mountains, and have not charity, I am
nothing. [1 Corinth. 13:2]
kh6...@pe.net
: Your lack of flats since the tire liners is probably as much due to chance as
: any protection they provide. Imagine a thorn large enough to get through your
: mountain-bike tire. How much longer does it have to be to get through the
: liner? 1mm? Less? What about that liner actually stops anything?
I tried to puncture a tuffy tire liner once with push pin and It would not
puncture the material. It only stretched the material. Tire liner are
very good protection against thorns and glass.
The material itself, though, has a tendancy to rub the inner tube where it
overlaps inside the tire casing and causes flats.
--------------------------------
Bob Masse' kh6...@PE.NET
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Rich Clark
"David L. Johnson" <david....@lehigh.edu> wrote in message
news:3B072A37...@lehigh.edu...
> n...@none.comspam wrote:
> Your lack of flats since the tire liners is probably as much due to chance
as
> any protection they provide. Imagine a thorn large enough to get through
your
> mountain-bike tire. How much longer does it have to be to get through the
> liner? 1mm? Less? What about that liner actually stops anything?
That it's made of a tough material that's difficult to penetrate?
My own experience with Mr. Tuffy liners is that I pull glass and nails and
staples and all kinds of other crap (no thorns, though) out of my tires
continuously, picked up on my Lindbergh Blvd./49th St/Grays Ferry route in
and out of Philly. I started using the liners after flatting three times
within a couple of weeks when I started using this route. I've had zero
flats since, 2000+ miles later. Same tires.
It's empirical evidence, but it's convincing enough for me.
I will say that I subjectively felt that adding the liners slowed me down a
touch, but not enough to care about... and there are too many other factors
at play to be really sure. Speculating, I supposed it's possible that the
added weight around the wheels' circumference is a possible cause (although
I know there are people here who would dispute that); another might be that
the liners, being stiff and flat, might tend to broaden the contact patch of
the tire, increasing rolling resistance.
RichC
Garry Lee / Gearóid O Laoi
I used it years and years ago for a long while.
But it will wear a hole in your tube if
1. you don't smooth the edge of the end by passing it over a lighting match.
2. Occasionally moving it.
It does slow you down. It increased tyre stiffness and that is the major
component of rolling resistance.
THe fastest tyres are smooth and supple.
terry morse
> I think that the liners make the tire stiffer and consequently the wheel
> encounters less rolling resistance. But that's only my opinion.
You're half right. Liners do make the tire stiffer, but they increase
rolling resistance instead of decreasing it.
Rubbers and plastics are called visco-elastic materials. When they are
deformed, they convert some of the energy to heat (the "visco" part).
The rest of the energy is returned when the material bounces almost
back to where it was (the "elastic" part).
The more visco-elastic material a tire has in its contact patch (tire
tread, liner, inner tube), the higher the rolling resistance. If you
want to visualize what's going on, think of the rubber/plastic in your
tire as chewing gum or silly putty.
--
terry morse
Palo Alto, CA
http://www.terrymorse.com/bike/
Jobst Brandt
> I think that the liners make the tire stiffer and consequently the
> wheel encounters less rolling resistance. But that's only my
> opinion. The ride is a bit harsher with liners. I think the weight
> effects are negligible. I use liners for the same reason: to cut
> down on flats.
That may be what you think but it isn't so. Rolling resistance is
primarily caused by elastomers of the tire flexing. These are the
tube, the casing binders, and tread. If you throw in an additional
gooey strip like Mr Tuffy, you only add to that loss because the tire
still deflects the same amount, that deflection being dependent on
inflation pressure, not how much additional stuff is in the tire.
Jobst Brandt <jbr...@hpl.hp.com>