Need ideas for 36" tire tread

I have contacted a tubular tire company about making the world's first
tubular 36" uni tire. Meaning a sew-up, where the tire & tube are one
unit, and mounted with glue to a hookless rim.

Tubular tires offer much lighter weight and less rolling resistance,
although some don't like the fact that you have to carry a spare and
some glue in the event of a flat.

Anyway, this company is willing to make the casing with tube inside.
But they do not actually make the rubber tread. Their standard practice
is for te customer to strip a tread off another (cheaper heavier) tire,
and they attach the tread to their casing.

Since the only 36" tires we have are clinchers, I don't know if it is
possible to strip off a tread that they could attach to the new tubular
casing.

It seems the tread would be a loop of rubber about 4cm wide, 4mm thick,
and 36" around (the same circumference as current tires). It would be
ideal to have a fine cross-pattern for the tread.

Thus: does anyone have any suggestions for finding a 36" loop of rubber
with such a tread pattern already on it?

I feel that this is a project worth pursuing, as tubulars rule the bike
world for performance applications, and don't go flat any more than
clinchers.

PS: please, no comments on how modern bike clinchers are just as good
as tublars...that is NOT our situation with the current crop of heavy
36" tires!


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If it requires cannibalizing a brand new 36" tire, how much are these
things likely to cost? Or could you use the tread from two "regular"
tires? That could be a lot cheaper, and also give you way more choices.
But still it sounds pretty expensive...


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Let me clarify. The tire company makes cotton and silk casings. All I
need to do is supply a continuous loop of rubber tread that they will
vulcanize to the casing to complete the prototype. If it goes into
production, they will be more interested in sourcing the treads
themselves.

So the tread has to be a continuous loop of rubber. I wasn't suggesting
that it absolutely had to be from a new 36" tire, although that would
seem to make it easier and guarantee the right size. But it cannot be 2
pieces fused together. Then you would have a sound and possibly a bump
twice per revolution.


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Very interesting. I really would like a 36" tire at half the weight. No
matter how long it would last or be priced.


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unijuul

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As long as the two joins are made neatly and accurately, I don't think
that you would notice any kind of bump when riding. And, as been
mentioned already, the choice of 26" tyre treads is extensive (and
cheap). The fact that it's a prototype should be enough of a reason
to choose a good tread design firstly and worry about the slight joint
mis-match less.

STM


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semach.the.monkey
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semach.the.monkey wrote:
worry about the slight joint mis-match less.



Which surely can be sanded/shaved off afterwards for the prototype?


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Sounds like a great idea, Pete. It seems to me that you'd have to
develop an overall system (i.e., wheel) with specific applications in
mind before spending any money. Here are some thoughts off the top of
my head that may help you work your way through this.

The first thing to think about is your application. Are you going for
a road-only application?

The second consideration is: what ultimate tire profile are you after?
It might be worth copying something like the thinner Big Apple for a
prototype. That way you are dealing with at least some known tracking
and turning characteristics, although of course those qualities will
change with a different tire composition. Another possibility is the
standard Coker tire profile since it provides stable straight tracking
and is easy to turn on pavement. A related question is: what ultimate
tire pressure are you trying to run at?

Once you know what profile you are after, what rim would you use? A
modified Airfoil? An unmodified Airfoil? The rim is a essential aspect
of forming your ultimate tire profile. The rim's materials and cross
sectional design will also determine the maximum spoke tension the
wheel will support (given a specific brace angle), so a related
question will be: how stiff does the wheel need to be? The wheel
stiffness will determine whether the wheel can be used with brakes and
how efficient it is during acceleration/climbing. The typical thing
that people think about, wider rims, is less relevant if your
application is road-only. So the rim should be designed with tire
profile in mind. Also, with higher pressures, the tire itself will be
the predominant factor in shaping the tire's cross-sectional profile,
and an important role of the rim is to act as a cradle for the tire.

Finally we can get to what outer rubber sources you can use. Your
tread choice will be determined by a) your application, and b) your
available raw sources and c) your ability to "edit" the tread. Here it
might be best, for a prototype, to use a thicker source than you might
ultimately desire. The additional thickness will make it easier for
you or the casing manufacturer to tailor the rubber and prepare it for
vulcanization. In addition, the casing manufacturer may have preferred
rubber types for the vulcanization process. I'm sure the three 36"
tires available have very different rubber types. Another
consideration: if you are removing the fabric from the tire to be
cannibalized, then ply is a minor consideration. Lastly, you might
analyze your rubber source for tread post-editability. For a
prototype, though, tread pattern is insignificant. There are so many
other variables that just getting through the process with a tire that
works for a few miles will be a huge step forward.

Once you can build prototypes fairly reliably, then it would be good to
investigate other ways to develop your own outer rubber, which is where
you will be able to fine-tune tread pattern and overall tire weight, as
well as feed back your results into the casing characteristics for
better handling and lighter weight.

Just some thoughts...


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U-Turn wrote:
Sounds like a great idea, Pete. It seems to me that you'd have to
develop an overall system (i.e., wheel) with specific applications in
mind before spending any money. Here are some thoughts off the top of
my head that may help you work your way through this.

The first thing to think about is your application. Are you going for
a road-only application?


Yes, strictly road use. A fine cross-file tread like bicycle road
tubulars is the idea.



The second consideration is: what ultimate tire profile are you after?
It might be worth copying something like the thinner Big Apple for a
prototype. That way you are dealing with at least some known tracking
and turning characteristics, although of course those qualities will
change with a different tire composition. Another possibility is the
standard Coker tire profile since it provides stable straight tracking
and is easy to turn on pavement.


The casing will be round, like all tubulars. The tread is just the
rubber strip on top of the casing. It doesn't have to be thick, and
would not work well if it was as thick as the TA or Nightrider. The
problem with "stripping" a tread off of a clincher is that the casing
is built into a clincher tire. That's why the more I think about this,
the more a plain rubber loop looks like the solution.



A related question is: what ultimate tire pressure are you trying to run
at?


Around 50 sounds good. I know the Nightrider is rated to 65psi, but
what do folks think about that? I have only briefly inflated a coker
tire to that pressure, and it is too hard for my liking. The idea of a
tubular tire would make for less rolling resistance at 30-50psi. Thus
maintaining some semblance of tire suspension effect.



Once you know what profile you are after, what rim would you use? A
modified Airfoil? An unmodified Airfoil? The rim is a essential aspect
of forming your ultimate tire profile. The rim's materials and cross
sectional design will also determine the maximum spoke tension the
wheel will support (given a specific brace angle), so a related
question will be: how stiff does the wheel need to be? The wheel
stiffness will determine whether the wheel can be used with brakes and
how efficient it is during acceleration/climbing. The typical thing
that people think about, wider rims, is less relevant if your
application is road-only. So the rim should be designed with tire
profile in mind. Also, with higher pressures, the tire itself will be
the predominant factor in shaping the tire's cross-sectional profile,
and an important role of the rim is to act as a cradle for the tire.


Agreed. The prototype will simply be an airfoil with the hooks ground
away.
Plenty of surface for gluing, and the width is in good tolerance for a
2" section.



Finally we can get to what outer rubber sources you can use. Your tread
choice will be determined by a) your application, and b) your available
raw sources and c) your ability to "edit" the tread. Here it might be
best, for a prototype, to use a thicker source than you might
ultimately desire. The additional thickness will make it easier for
you or the casing manufacturer to tailor the rubber and prepare it for
vulcanization. In addition, the casing manufacturer may have preferred
rubber types for the vulcanization process. I'm sure the three 36"
tires available have very different rubber types. Another
consideration: if you are removing the fabric from the tire to be
cannibalized, then ply is a minor consideration. Lastly, you might
analyze your rubber source for tread post-editability. For a
prototype, though, tread pattern is insignificant. There are so many
other variables that just getting through the process with a tire that
works for a few miles will be a huge step forward.


I'm still thinking a plain loop of rubber, in the dimensions as
previously posted. To try to strip the casing out of a 36" tire would
take too long, and probably result in a tread much heavier than
necessary.
To give you a better idea, go to any good bike shop and examine how
thin the treads are on a road (not pista) tubular. That's what I'm
after.



Once you can build prototypes fairly reliably, then it would be good to
investigate other ways to develop your own outer rubber, which is where
you will be able to fine-tune tread pattern and overall tire weight, as
well as feed back your results into the casing characteristics for
better handling and lighter weight.


I still have to have a conversation with the company about the final
source of treads. Because they specialize in customers sending them
treads to make into fine handmade tires, they don't have all the
materials at their disposal.
hence maybe I just get a 4mm thick piece of rubber and cut a loop to
shape.
I'm not worried about the durability of the compound right now. I'm
more interested in riding the handmade casing.


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unisk8r nice going, looking into a lighter tire/tube for the 36" wheel.
This combo tire tube is something I'm not familiar with, but sounds
like a great solution.


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Chrashing

Regards,
Ken

I've been flying.......
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Here's a thousand more words:

http://www.worldclasscycles.com/duga...ada_cotton.htm


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