Re: [CR] 753 vs 531 (Important!)

(Example: Framebuilders)

From: <gpvb1@comcast.net>
To: classicrendezvous@bikelist.org
Subject: Re: [CR] 753 vs 531 (Important!)
Date: Sun, 03 Jul 2005 16:27:20 +0000

Date: Fri, 01 Jul 2005 10:50:08 -0500 From: John Thompson <JohnThompson@new.rr.com> To: classicrendezvous@bikelist.org Subject: Re: [CR]753 vs 531

Tom Dalton wrote:
> Can anyone explain why Reynolds initially made the 753 tube set in an
> unusual diameter? With such thin walls, the 26.8 post sizes imples
> that the OD was significantly smaller than "normal". I have seen a
> whole lot more 531 tubes in the imperial size than the smaller,
> metric size. So, why did they initially offer 753 in the less common
> O.D.?

Reynolds made both Imperial and Metric sizes from the beginning, but the first few years of Imperial production were exclusively for Raleigh, so everybody else had to use metric.

--

-John Thompson (john@os2.dhs.org) Appleton WI USA ------------------------------

John:

Do you mean 753? Do you know this, or are you just guessing? Because it doesn't make sense. All of the early 753 Team Pros are made with Metric 753 tubing.....

Folks, it seems that something needs clarifying here. 531 DB tubing was available in Imperial and Metric diameters. This is why a standard-gauge French 531 DB frame takes a 26.6 diameter seat post, whereas an English one requires a 27.2 post. The wall thicknesses are the same, but the O.D. of the tube is 0.6 mm different (28.0 vs 28.6). The original 753 tubing (I'm not talking about 753R) only came in Metric diameter sets. I'm not sure why this happened, but I can guess that it was a tooling availablity issue. Why tie up a set of high-volume Imperial-diameter Production tooling for what probably started out as an R & D exercise?

Later, 753R was introduced, and was available in Imperial diameters (only?). Ilkeston switched to the new tubing at that point, which allowed them to use Imperial-diameter frame fittings (Cinelli BB shell, other lugs, etc.).

Don't confuse a standard-gauge 753 frame with a 26.8 seat post with a heavy-gauge 531 frame with a 26.8 seat post. The seat tube I.D.s are the same, but the tube O.D.s are different.....

Greg Parker Madison, Wisconsin Where the fireworks, Blackhawks, and F18s were amazing last night.