Hooked-edge rims: anybody know the patent or earliest example?

Recently I have been pondering a question concerning radial bicycle tires.
The back story:

1. When Jobst discussed radial tires for bicycles once, he said that
radials needed stronger beads than usual, because the casing threads did
not carry any of the circumferential load the way that bias-ply tires
threads did (which would be true) but-

2. Jobst also played a part in the famous "cut-bead" test, which claimed
that the bead tension did not play a major role in keeping modern tires
on modern hook-edge rims, but-

3. When I asked if the beads of the old Panasonic radial tires were any
thicker than usual, people who had seen them said not noticeably.

4. And yet when I did the math, a radial tire of 559mm x 37mm would need
a bead about five times stronger than the bias-ply tire the same size
would.

-----

The main issue here is the matter of hook-edge rims and what relative
improvement they are over straight-edge.... and I haven't been able to
find any technical-style info on that matter.

How much more "holding force" does a hooked-edge rim offer over a
straight-side rim?,,,, I would guess that vintage bicycle articles of
the era (when hook-edge rims began to become common) would have
attempted to explain the practical differences. I am hoping that the
patent would offer up some data, but I haven't been able to find the
patent yet.

On 12/2/2013 4:09 PM, Doug Cimperman wrote:
Recently I have been pondering a question concerning radial
bicycle tires.
The back story:

1. When Jobst discussed radial tires for bicycles once, he
said that radials needed stronger beads than usual, because
the casing threads did not carry any of the circumferential
load the way that bias-ply tires threads did (which would be
true) but-

2. Jobst also played a part in the famous "cut-bead" test,
which claimed that the bead tension did not play a major
role in keeping modern tires on modern hook-edge rims, but-

3. When I asked if the beads of the old Panasonic radial
tires were any thicker than usual, people who had seen them
said not noticeably.

4. And yet when I did the math, a radial tire of 559mm x
37mm would need a bead about five times stronger than the
bias-ply tire the same size would.

-----

The main issue here is the matter of hook-edge rims and what
relative improvement they are over straight-edge.... and I
haven't been able to find any technical-style info on that
matter.

How much more "holding force" does a hooked-edge rim offer
over a straight-side rim?,,,, I would guess that vintage
bicycle articles of the era (when hook-edge rims began to
become common) would have attempted to explain the practical
differences. I am hoping that the patent would offer up some
data, but I haven't been able to find the patent yet.

Probably because the American hook edge decimal series
(26x1.75/2.125 has survived as the current MTB standard,
26x1.375 is lost to history now) are so old that no one
remembers or much cares. 1930s if I recall but I'm not sure.

The modern hook edge for road rims started with the joint
Mavic type E rim and matching Michelin Elan tire in the late
seventies. That is indeed a big difference from
straight-side rims, allowing not only smaller sections with
higher pressures but also the use of a not-steel bead.

Sorry I can't quantify that, but suffice to say that Jobst's
snip-bead test would not be possible at all with the
previous straight side rims. If you are able, check out a
steel rimmed 27" system (Schwinn Varsity, Peugeot UO8 etc)
at some local shop. You'll get it once you look at the
tire-rim interface.

This is from about 1980, just after the Mavic E rim, when
both styles were still in production:
http://www.yellowjersey.org/photosfr...t/WEINRIMS.JPG

--
Andrew Muzi
www.yellowjersey.org/
Open every day since 1 April, 1971

Read Brandt's work on line. Weighty. However, when JB seems to wander off check back into context.

Straight rims allow contact patch flex to roll with the rim where hooked edge rims stop flex or a hi percentage moving flex into heat...eg the straights are faster, more grippy cornering. ???

Hooked are safer for normal people riding normally with the usual no maintenance or inspection regimen

BTW, information from patents runs counter to the device.

On Mon, 02 Dec 2013 16:09:01 -0600, Doug Cimperman
wrote:

Recently I have been pondering a question concerning radial bicycle tires.
The back story:

1. When Jobst discussed radial tires for bicycles once, he said that
radials needed stronger beads than usual, because the casing threads did
not carry any of the circumferential load the way that bias-ply tires
threads did (which would be true) but-

2. Jobst also played a part in the famous "cut-bead" test, which claimed
that the bead tension did not play a major role in keeping modern tires
on modern hook-edge rims, but-

3. When I asked if the beads of the old Panasonic radial tires were any
thicker than usual, people who had seen them said not noticeably.

4. And yet when I did the math, a radial tire of 559mm x 37mm would need
a bead about five times stronger than the bias-ply tire the same size
would.

-----

The main issue here is the matter of hook-edge rims and what relative
improvement they are over straight-edge.... and I haven't been able to
find any technical-style info on that matter.

How much more "holding force" does a hooked-edge rim offer over a
straight-side rim?,,,, I would guess that vintage bicycle articles of
the era (when hook-edge rims began to become common) would have
attempted to explain the practical differences. I am hoping that the
patent would offer up some data, but I haven't been able to find the
patent yet.

I can't say but I have certainly read in tire specification a
statement that "Must be use on wheels with a hooked rim" or words to
that extent which would seem to imply that the hook does something".

Continental has this to say about their Grand Prix 4000S Road Ty

"These tyres are for racing style bikes that use clincher/hooked rims,
these are the most common fitment and hook onto the rim and require an
inner tube".
--
Cheers,

John B.