Reviving this thread after 4 years, because of a conversation on another thread, regarding what 653 actually is (it is still as clear as mud!).
Amongst so much rumour and conjecture, the 'facts' we know are:
- 653 has same gauge main tubes as 753 (though supposedly heavier, which makes no sense)
- Made of MnMo, not CrMo (so, same material as 531 and 753)
- Mixed strength tubeset (strong forks, stronger main triangle, strongest rear triangle)
- 753 and 531 are essentially the same material, with 753 receiving thinner gauges and heat-treatment
Questionable 'facts':
- Merckx had anything to do with 653 - just because a Reynolds employee said it, doesn't make it true. I worked for a global company, where dozens of myths were propagated, either out or ignorance or laziness, or because people thought it was fun to make up stuff for customers!)
- The idea that the main triangle is just 531/531Pro - it is thinner gauge than 531 and, according to Raleigh, stronger than 531Pro (although, see point above, about misinformation)
- That 725 has any place in this story. It was released to the public more than 10 years after, and is CrMo, not MnMo. Did Reynolds make a new product, and hide it for a decade, to make stays for a tubeset that was around for only a couple of years? Seems implausible.
My best guess is that 653 main tubes are something between 531 and 753. If 753 is heat-treated 531, drawn thinner; then 653 is likely to be 531, non-heat-treated, drawn to the same gauge as 753, and then some additional strengthening (cold-working?) so, neither 531P nor 753?
Also, if it uses 753 rear stays, why are non-753 certified builders allowed to use it? And why can 653 frames have chromed stays, whilst 753 supposedly can't?