The 653 tubeset uses 531 tubing for the main tubes and fork and 753 tubing for the stays, it is not a tubing or alloy in it's own right......so there!
For (almost) all your Reynolds tubing arguments.. http://www.equusbicycle.com/bike/reynolds/Reynolds-transfers.jpg
@hippy started
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For (almost) all your Reynolds tubing arguments..
http://www.equusbicycle.com/bike/reynolds/Reynolds-transfers.jpg