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

(Example: Events:Cirque du Cyclisme:2002)

In-Reply-To: <4AB36C29.60004@m-gineering.nl>
References: <916999.14422.qm@web82206.mail.mud.yahoo.com> <4AB3350F.9030805@nonlintec.com> <7543b4a40909180316i2c15ea46h4f52c8cee8e47b65@mail.gmail.com>
Date: Fri, 18 Sep 2009 13:33:35 +0200
From: "Ken Freeman" <kenfreeman096@gmail.com>
To: M-gineering <info@m-gineering.nl>
Cc: Classic Rendezvous <classicrendezvous@bikelist.org>
Subject: Re: [CR] Bottom Bracket Cups & Threads - Why do they stay tight or loosen?


And why I advocate finding and adhering to a proper torque spec and torquing spec.

On Fri, Sep 18, 2009 at 1:16 PM, M-gineering <info@m-gineering.nl> wrote:
> Ken Freeman wrote:
>
>> On Fri, Sep 18, 2009 at 9:21 AM, Steve Maas <bikestuff@nonlintec.com>
>> wrote:
>>
>> Jerome & Elizabeth Moos wrote:
>>>
>>>
>>> .....I've long said that the technically correct ISO BB standard would
>>> have been Swiss, since it was metric, and had the correct LH thread o
>>> on the fixed cup. But of course that decision was made based on market
>>> share, not technical logic. At least the English thread anointed ISO
>>> did happen to have the "correct" LH fixed cup as well.
>>>
>>> It's important to remember that the purpose of standards is to normalize
>>> what most people are doing already, not to determine what's best and try
>>> to
>>> force everyone to do it. That almost never works. On rare occasions when
>>> it's been attempted, people just ignore the standard and adhere to some
>>> kind
>>> of de facto standard, which is established by everyone immitating some
>>> common practice.
>>>
>>> French dimensions are a good example of an attempt to create a standard
>>> apart from common practice. We all know how well that went!
>>>
>>> As for BBs--is the ISO standard based on British dimensions the only one?
>>> I'm away from home and my books, so I can't check. There's no reason why
>>> there can't be multiple standards for some type of item.
>>>
>>> Steve Maas
>>> Göteborg, Sweden
>>>
>>>
>>> I can attest first hand to this logic of standardization. I'm writing an
>>>
>> ISO standard in another field, and the primary purpose is to promote
>> global
>> trade by establishing a common language for design and description of
>> products in the relevant domain. There is a great tension between the
>> standard writing team and some of the reviewers. Many reviewers think
>> that
>> the purpose of the standard is to show what is the limit of concievable
>> technology, the best engineering solution, or what their sponsors think is
>> best.
>>
>> Back to BB engineering:
>>
> If a reversed thread was
>
>> absolutely necessary in all potential cases, we would have to see hub
>> locknuts using both a righty-tighty and a lefty-tighty design. However,
>> they don't.
>>
>
>
> which is why it's more often the rh cone which you find has loosened.
> --
> mvg
>
> Marten Gerritsen
> Kiel Windeweer
> Netherlands
>
> _______________________________________________
>

--
Ken Freeman
Ann Arbor, MI USA