I asked the original question while at work, then at home found I had an article from "Bicycling" magazine in July 1988 (pg 110-118) that gave some relevant data (thicknesses in mm, weight in gm). It has specs for 56 different steel tubesets from all of the major maufacturers of that era.
531ST 531C 653 753R Top tube: .81/.55/.81 .81/.55/.81 .71/.55/.71 .71/.55/.71 Down tube: 1.02/.71/1.02 .91/.61/.91 .81/.55/.81 .81/.55/.81 Seat tube: .81/.55 .81/.55 .71/.55/.71 .71/.55 Chainstays: .81 .81 .61 .61 Seatstays: .91 .55 .61 .61 Tubeset weight: 1.935 1800 1700 1650
Doesn't say what size the weights relate to. It is not stated explicitly but I presume that the tubeset weight includes fork. My 56cm 531C bare frame weighs 1890gm on the kitchen scales. As a comparison Columbus SL tubeset supposedly weighs 1932, SP 2295, TSX 1945.
Also gives fork data, but I got bored typing... .
Another article I have lists the UTS (N/mm2) of each grade as: 531: 802 653: 929 753: 1315
It would appear that by this stage the 531SL had been replaced by the 653?
I'm surprised that the 753 is only 50gm lighter than the 653, 150gm lighter than 531C. A lot more $ for not much less weight!
Mark Battley, Auckland, New Zealand.
Reynolds 531C was just a simple naming of 531 db tube sets when the more specific Special Tourist and SL names were introduced. Reynolds 531 has always been available in a variety of gauges and until the 1980s REynolds did not distingush on the tube sticker between them. SL however was a new thin walled version introduced in the 70s. You would be almost right in your assumption about 531SL being the same as 653. The tube gauges were pretty much the same but the main triangle tubes of 653 featured slightly enhanced strength tubes compared to 531 and the rear triangle used 753 tubes - good builders of course silver soldered these. Hilary Stone
> To the best of my knowledge, Reynolds 531C is a set having double
butted
> tubes with .9/.6 mm wall thickness. 531 ST(Special Tourist) has 1.0/.7
walls,
> and 531 SL(Special Lightweight) has .8/.5 walls. Was this (531 SL)
basically
> the same as 653?