get a tuning fork, hit it against the top tube..
if it makes a sound like this then it's 531
and if it sounds like this then it's 501
.. there is an outside chance it's columbus tubing, in which case it will sound like [ame="http://www.youtube.com/watch?v=7OvsVSWB4TI"]this[/ame ]
@dan started
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get a tuning fork, hit it against the top tube..
if it makes a sound like this then it's 531
and if it sounds like this then it's 501
.. there is an outside chance it's columbus tubing, in which case it will sound like [ame="http://www.youtube.com/watch?v=7OvsVSWB4TI"]this[/ame
]