This is what breton bikes has to say about 531st tubesets:
The standard 531 set is the 531c racing tubeset which makes for a
frame around 4 1/4lbs. This builds up into a fine responsive frame
ideally suited to road racing, but lacking a little stiffness in the bottom
bracket area. For smaller frame/riders it also make a nice touring
frame, but it really has too much flex to be good for someone carrying
full cyclecamping loads on a larger frame. To solve this weakness
531 st has a heavier gauge down tube which resists the flexing which
causes the dreaded speed wobbles on a loaded tourer. It also has
beefier stays for the loads imposed by cantilever brakes. The taper
gauge forks are of a flattened oval profile to give clearance for wider
tyres without using wide fork crowns, and that's it...
So it might make sense to use 531st to achieve the extra stiffness you'd want for track sprinting in a larger frame that would otherwise be relatively flexible on account of its longer tubes?
This is what breton bikes has to say about 531st tubesets:
So it might make sense to use 531st to achieve the extra stiffness you'd want for track sprinting in a larger frame that would otherwise be relatively flexible on account of its longer tubes?