Re: [CR] Ebay Outing : Rudge Pathfinder 22.5", 1960.


Example: Bike Shops:R.E.W. Reynolds

Date: Fri, 24 Jul 2009 17:17:11 +0100
From: Hilary Stone <hilary.stone@blueyonder.co.uk>
To: donald gillies <gillies@ece.ubc.ca>
References: <20090723211451.1CCE219D8D@ug6.ece.ubc.ca>
In-Reply-To: <20090723211451.1CCE219D8D@ug6.ece.ubc.ca>
Cc: classicrendezvous@bikelist.org
Subject: Re: [CR] Ebay Outing : Rudge Pathfinder 22.5", 1960.


A frame made from two types of steel (for example 2030 carbon steel and Reynolds 531) made with identical butting,wall thicknesses and dimensions will flex identically. The modulus of elasticity (some people will know this as Young's Modulus) of different steel alloys is to all intents and purposes identical - differences will be of the order of less than 0.1%... However all Raleigh steel frames built from 2030 carbon steel use quite thick walled seamed tubing so are most definitely stiff and unyielding... I have never seen one of these frames with butted tubing. All take 25.4mm seatposts. It may well be true that later Raleigh frames put on some weight but that could easily be due to the use of heavier lugs and BB shells - Raleigh pressed lugs and BB shells made in-house were really quite finely made from thin steel sheet. Later they bought in proprietary lugs and even the in-house made ones seem cruder and thicker walled. Raleigh 2030 carbon steel frames generally weighed about 2.8-3kg. Ones made with 531 plain gauge main tubes shaved off about 400g whilst 531 DB frames would weigh under 2kg - often as light as 1800g with good quality pressed steel lugs, BB shell and fork ends.

Hilary Stone, Bristol, British Isles

donald gillies wrote:
> Yes the bike is made of Raleigh 2030 carbon steel, but what matters
> more is the gauge and butting of the steel used, not the carbon (or
> chromoly) content of the steel. In the late 50's through the early
> 1970's it was common to make "club racers" out of thin-walled 2030
> carbon steel. Yes, the frame would be a little bit more flexible than
> a reynolds frame of exactly the same gauge, but the butting and thin
> tubing walls would give the bike a lively reynolds-like feel, with
> just slightly heavier tubes that weighed a few (maybe 4-8) ounces more
> than a reynolds 531 frameset.
>
> In my experience, the double-butting in the forks and main triangle
> are responsible for the lightness and lively feel of high-end bikes.
> The alloys used to increase the tubing strength and lighten the frame
> are a 2nd-order optimization compared to double butting.
>
> I had a double butted tange steel frame on my SEKAI 2500, 25 lbs with
> a very lively ride. There was no indication that it was chromoly
> tubing - the decal just said 'Tange Double Butted Steel'. By
> replacing some midrange japanese components on that bike (bottom
> bracket, crank, freewheel, rims, etc.) I could easily have dropped
> that bike down to 23 lbs.
>
> Club Racers came to an end with the introduction of CPSC crash-test
> regulations in 1977-78. These regulations made club racers impossible
> to sell in the USA market. Low-end bicycle immediately increased in
> weight due to these regulations.
>
> If it's a club racer, then the campagnolo gran sport derailleur (350?
> 400? grams) is the most likely reason that the bike might accelerate
> like a boat anchor ...
>
> - Don Gillies
> San Diego, CA, USA