Re: [CR] Bottom Bracket Cups & Threads - Why do they stay tight or loosen?

(Example: Racing:Jean Robic)

Date: Fri, 18 Sep 2009 07:12:41 -0700
From: Jerome & Elizabeth Moos <jerrymoos@sbcglobal.net>
To: Classic Rendezvous <classicrendezvous@bikelist.org>, Steve Maas <bikestuff@nonlintec.com>
In-Reply-To: <4AB3350F.9030805@nonlintec.com>
Subject: Re: [CR] Bottom Bracket Cups & Threads - Why do they stay tight or loosen?


AFAIK, the ISO standard which sanctifies the old English thread is the only one for road bikes, although perhaps there may be separate standards for BMX bikes or such like.

As to French thread, it evidently worked quite well for perhaps nearly a century. The French having invented the metric system during the reign of Napoleon, would not have been expected to use anything but metric dimensions for bicycles. But the British, and least we forget, the Americans, were also poineers in manufacturing high quality bicycles beginning in the last half of the 19th century. So metric and English threading coexisted for a century until the growing Japanese dominance, oriented toward the US market and therefore often using English thread, took over in the 80's, establishing a de facto standard which ISO formalized.

One thing I've long been curious about is just how old were the post-WWII threading standards we call English, French, Italian and and Swiss? Did they originate in the late 19th century or only after WWII? It has been speculated that the curious mix of metric and English dimensions called Italian thread was the result of British and American machine tools used in the reconstruction of Italy after WWII. So what threading did Italian bikes use before WWII? Was it essentially the same metric thread as French, or perhaps Swiss? Or a unique metric thread? Also, does the thread now called ISO, fomerly known as English, trace its origins to the late 19th century British bikes, or to late 19th century American bikes? Or both? Or neither? The British seem to have used a variety of threading standards, with both Raleigh and Chater Lea using BB thread different from "English" plus the whole subject of Whitworth thread. So did "English" thread only become more or less standard after WWII? Or was it perhaps only "English" in that it used English dimensions, perhaps originating in the American bike industry rather than the British one?

Anyone have enough information about late 19th century/ early 20th century Frecnh bikes to know if they used essentially the threading called French after WWII?

Regards,

Jerry Moos

Big Spring, Texas, USA


--- On Fri, 9/18/09, Steve Maas wrote:


> From: Steve Maas <bikestuff@nonlintec.com>

\r?\n> Subject: Re: [CR] Bottom Bracket Cups & Threads - Why do they stay tight or loosen?

\r?\n> To: "Classic Rendezvous" <classicrendezvous@bikelist.org>

\r?\n> Date: Friday, September 18, 2009, 2:21 AM

\r?\n> Jerome & Elizabeth Moos wrote:

\r?\n>

\r?\n>

\r?\n> .....I've long said that the technically correct ISO BB

\r?\n> standard would

\r?\n> have been Swiss, since it was metric, and had the correct

\r?\n> LH thread o

\r?\n> on the fixed cup.  But of course that decision was

\r?\n> made based on market

\r?\n> share, not technical logic.  At least the English

\r?\n> thread anointed ISO

\r?\n> did happen to have the "correct" LH fixed cup as well.

\r?\n>

\r?\n> It's important to remember that the purpose of standards is

\r?\n> to normalize what most people are doing already, not to

\r?\n> determine what's best and try to force everyone to do it.

\r?\n> That almost never works. On rare occasions when it's been

\r?\n> attempted, people just ignore the standard and adhere to

\r?\n> some kind of de facto standard, which is established by

\r?\n> everyone immitating some common practice.

\r?\n>

\r?\n> French dimensions are a good example of an attempt to

\r?\n> create a standard apart from common practice. We all know

\r?\n> how well that went!

\r?\n>

\r?\n> As for BBs--is the ISO standard based on British dimensions

\r?\n> the only one? I'm away from home and my books, so I can't

\r?\n> check. There's no reason why there can't be multiple

\r?\n> standards for some type of item.

\r?\n>

\r?\n> Steve Maas

\r?\n> Göteborg, Sweden