RE: [CR]the odds on tandem transfer cog tooth count

(Example: Framebuilders:Mario Confente)

From: "Mark Petry" <mpetry@bainbridgeisland.net>
To: "'David Benson'" <david@worrall.co.nz>, <classicrendezvous@bikelist.org>
Subject: RE: [CR]the odds on tandem transfer cog tooth count
Date: Tue, 8 Apr 2003 20:16:42 -0700
In-Reply-To: <3E937DE7.1000702@worrall.co.nz>


David - BZZT! Empirical results obtained on a schwinn town and country are completely irrelevant! No data will be accepted unless the experimental testbed is an all 531 or Columbus tubed frame of fillet brazed or lugged construction!

As for your measurements of the boob toob, the radius of the eccentric will more than compensate for any irregularities in chain length. The prime number hypothesis stands until disproved with REAL data! And none of this half link stuff (altho I must admit I stopped for a moment to consider the implications of this un-anticipated development.

WHO has read the masterpiece / tour de force "Cryptonomicon" by Neal Stevenson ? In that book, there is a description of a great piece of empirical mathematics performed by the polymath Allan Turing, inventor of the stored program computer, while on a bike ride in southern England in 1942. His chain has a sticky link, and his chainwheel, a bent tooth. Every so many fractions of a mile, the chain pops off! He does, in his head, during the ride, he does the calculus about the frequency of a sticky chain link, hitting a tooth on the rear cog, blah blah blah. How appropos the present discussion!

Worth hunting for if you are so inclined.

Anyway!

===================================================== Mark Petry 206.618.9642 Beautiful Bainbridge Island, WA mpetry@bainbridgeisland.net

===================================================== "Fighting a preemptive war is as irrational as committing suicide because one fears death."

--Otto von Bismarck =====================================================

-----Original Message----- From: David Benson [mailto:david@worrall.co.nz] Sent: Tuesday, April 08, 2003 5:57 PM To: HM & SS Sachs Cc: mpetry@bainbridgeisland.net; Classicrendezvous@bikelist.org Subject: Re: [CR]the odds on tandem transfer cog tooth count

HM & SS Sachs wrote:
> Whoa! Mark, I'm going to take the bait. In a series of miserable,
> unplanned, empirical experiments involving an on-topic Schwinn
> Town-and-Country and transfer cogs ordered from R.E.W. Reynolds in
> England, I was forced to confront the fact that tandem eccentric
> bottom brackets can only take up a limited amount of chain. The exact
> length of the "boob tube" (bottom bracket connector tube) on that bike
> was such that it absolutely required even numbers of teeth on the
> transfer cogs. With a slightly shorter boob tube, I suspect that only
> odd tooth numbers would work. Evens worked fine on the T&C, and
> allowed use of the eccentric to take up slack as the chain wore. Odd
> tooth rings could only be set up as too-loose, or won't-stretch-to-fit.

So DB asks:

Harvey, Did you try putting a half link in the chain?

DB
Auckland, NZ