Re: [CR] Chain-rub With A Very Wide Range Double

(Example: Racing:Jacques Boyer)

Date: Sun, 27 Jun 2010 12:52:50 -0700
From: <mrrabbit@mrrabbit.net>
To: John Clay <jmedclay@yahoo.com>
References: <593104.3981.qm@web51101.mail.re2.yahoo.com>
In-Reply-To: <593104.3981.qm@web51101.mail.re2.yahoo.com>
Cc: Classic Rendezvous <classicrendezvous@bikelist.org>
Subject: Re: [CR] Chain-rub With A Very Wide Range Double


Old news...the "don't run small ring / small cog" advice is almost run of the mill advice wilth all setups regardless of vintage, brand and model.

There are exceptions...it's just a general rule of thumb. Large to large sticks up on the radar as well...

However, in your case you mentioned the problem occurs with your second cog up...normally I don't expect the problem to continue once out of the smallest cog.

It's probably been discussed many time over here and elsewhere - likely noted in a Sutherland's manual as well. Try searching the archives...

=8-)

Robert Shackelford San Jose, CA USA

Quoting John Clay <jmedclay@yahoo.com>:
> I have discovered that when on the small ring and smallest two cogs the chain
> rubs the inside surface of the large ring. It's a Stronglight 99, 48/28 with
> shortest BB spindle projection on right side possible.  Is that a known issue
> with wide range double arrangements? I haven't calculated the geometry (will
> undoubtedly do so), and I know that on this particular frame I skewed the BB
> alignment a skosh, in a direction that would exacerbate this issue
> (fortunately I know why). Still, I wonder if this is part and parcel of such
> a large difference in the diameters of the two rings. Anyone?
>
> John Clay
> Tallahassee, Florida
> USA
>
> http://healthcarefunding.blogspot.com/
> Single Payer IS the compromise.
>
>
>
>
> _______________________________________________
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