Generally a 531 tubeset was just a bit lighter than Columbus SL. The 531 top and seat tubes tended to be slightly thinner, I believe .5 mm butted to .8 mm. Columbus SL was butted from .6 mm to .9 mm.
Here's some info about Reynolds tubes:
http://www.equusbicycle.com/
Note that by the date of the catalogue, Reynolds 531 came with four tubesets and weights.
I seem to recall a road test in "Bicycling" magazine years ago where two Bruce Gordon frames were constructed with identical geometries, but were made with different tubesets, one Columbus SL and the other Tange Prestige. One was painted blue and the other was painted pink. I do not remember which was which, but all riders thought one frame was lighter and rode better, until they weighed the bare frames. The heavier Columbus SL frame was prefered by all. We are talking only ounces here.
Oh, cool... Please check this out:
http://www.desperadocycles.com/
Paul Haussler (Fuso Luxe with TSX, but off timeline, rider) Huntington Beach, CA
Date: Wed, 30 May 2007 15:27:08 -0500 From: <jeff-arg@bizwi.rr.com> To: <classicrendezvous@bikelist.org> Subject: [CR]Reynolds 531 vs. Columbus SL Message-ID: <5p5kll$l5ab5@rrcs-agw-02b.hrndva.rr.com> Content-Type: text/plain; charset=iso-8859-1 MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Precedence: list Message: 13
An friend of mine and I were talking about bikes last night and he asked, "wasn't the Columbus SL tubing allways lighter than Reynolds 531?" I couldn't give a definitive answer. My inclination was to agree. However, I have a digital scale that is on my bike stand and thought about some of the bare frames (sans forks) that I have weighed. The Colnagos built with SL are typically around 1900 grams but so are the Masi's built with 531. A Windsor I just bought made of SL is actually heavier than a Raysport I have made of 531.
Does anyone know of standardized tubing weight measures between 531 and SL for comparison?
Jeff Pyzyk
Milwaukee, WI