>>I'll take a stab at this, even though I'm sure more informed persons will correct my errors.
I'm probably not more informed, but I have additional info, FWIW
>>531 is the oldest, then 753, then some other numbers, and then 853 and 653.
I'm pretty certain that 653 came about well before 853. 653 was the same heat treated stays (and blades?) as 753 with a work hardened version of the 531 main triangle...or something like that. It ended up being a lighter set than 531C but heavier than 753R. Builders will now jump in and say that every Reynolds tube was available in numerous gauges, but I will maintain that the "C" and the "R" implied specific dimensions..
>853 is a stronger alloy, and is heat treated and drawn in thinner tubes than 531 for a lighter weight tube set.
853 is an air hardening material intended for TIG welding (can also be brazed). With this material, post-weld heat treatment is unnecessary (actually the welding and air cooling are the heat treating process).
>653 is supposed to be similar to 853, but lacks the heat treating. So 653 is lighter than 531 and a >bit stronger, but not as strong/light as 853. But it is cheaper than 853.
This may be how Reynolds was positioning 653 once 853 came out, but that isn't what they said early on. It was more of an intermediate set between the pedestrian (531 durable, good) and the exotic 753 (brittle, light).
Tom Dalton Bethlehem, PA
I just purchased that Bob Jackson frame from ebay. I looked up Reynolds tubing types on their web site and could find no reference to 653 tubing which this bike is. Is there a comprehensive site for tubing types somewhere or does anyone know how 653 fits into the Reynolds line up. A secondary question. I see a lot of emphasis on 531 tubing almost like it is the Holy Grail of bike tubing. Yet I see that is has been around since 1935 and surely metallurgy has progressed since then so why the fascination with this tubing. Since I am still new to the lightweight world this may seem like a stupid question but that never stopped me before.