On 1/14/2020 6:54 PM, jbeattie wrote:
On Tuesday, January 14, 2020 at 3:58:27 PM UTC-8, Mark J. wrote:
On 1/14/2020 10:34 AM, AMuzi wrote:
On 1/14/2020 11:51 AM, jbeattie wrote:
On Tuesday, January 14, 2020 at 9:10:48 AM UTC-8, Mark J. wrote:
So I learned (?) something new (?) today reading Lennard Zinn's column
at Velonews:
https://www.velonews.com/2020/01/tec...blowoff_503717


What I learned was the term "crochet-type rim".

Looking it up, some sources say this is just another name for hook-bead,
BUT:

https://en.wikipedia.org/wiki/ISO_5775#Rims   says:

    Both crochet (C) and hooked-bead (HB) rims have inner profiles
    that curve inwards near the outside diameter of the rim to
    provide a hook that helps retain the tire bead under high
    pressure. On modern bikes crochet rims are most common and
    hooked bead rims are rare. The distinction is primarily that
    hooked-bead rims lack the defined bead seat of straight side and
    hooked bead rims. The tire is held in position radially by the
    hook without a bead seat playing a role. Without a bead seat,
    the primary designation of the diameter in terms of the bead
    seat is not applicable, and the governing diameter is the OD.

Sentence #3 pretty clearly has a typo, but I can't figure out the
correction, and I cannot find any images on google that directly compare
hooked-bead and crocheted (also sometimes mis-named "crotched").

I suspect the "HB" in the quoted passage above is really referring to an
obsolete design, and that the quoted writer would even call the 70's
Mavic Mod E "crocheted" rather than "hooked-bead," even though we all
called them hooked-bead.

Can anyone clear this up with an authoritative source?

Mark J.

I'm sure there must be an ISO drawing somewhere.
https://en.wikipedia.org/wiki/ISO_5775Â My sense is that we've been
calling ISO "crochet" rims "hook bead" rims but that a true "hook
bead" looks like an open hook ala the old steel rim design.
http://www.asia.ru/images/target/pho.../Steel_Rim.jpg


Yes, that's correct.
Rims with a lip and also a bead seat, such as items #571 and #A125 he
http://www.yellowjersey.org/photosfr...t/WEINRIMS.JPG

are the modern standard design.


Thanks, Jay & Andrew. SO I gather that in the quotation above the
author intended to say:

The distinction is primarily that
hooked-bead rims lack the defined bead seat of straight side and
/crochet/ rims.

Somehow, I think I'm just gonna keep calling them "hooked-bead." It's
worked for me for forty years.

Mark J.

Until today, I had never heard the term crochet rim. I always called them hook bead rims as distinguished from straight sided rims -- like the Wolber concaves Andrew linked. I built a set of those 4X 27" (I think). Anyway, they were 310mm spokes, and I still have a bunch of them. Totally useless unless I get a $zillion Phil spoke cutter-threader. I don't even remember what I did with the wheels. They weighed a ton, and I hated them. I think I replaced the rims with Mod 58s -- my standard crochet bead touring rim.

-- Jay Beattie.


Yeah Weinmann A124/A129 were real pigs.

But we sold tons of them, used to buy them in case-of-50
700C, 27", 36 and 48 drill. For people who eat rims, those
were nearly indigestible.

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