Small animation with Raphael
I really like what you wrote there, though I am afraid at this point you ought to expand the code, not reduce it.


r, r1, r2, cx, cy, beta are all variables that need better ( more meaningful ) names
You need to indent your code, just hit TidyUp in your fiddle and you will see
This is not part of your core code, but you should not simply assign something to window.onload, you should use addEventListener
Your code had support for using custom colors, and then you took it out, if you really want to take that out, then you should also take out the parameter, the commented out code and the  if (color == "rainbow"){ statement
in your var statement, you could simply do cy = cx
be consistent in your name, and use lowerCamelCase: stroke_width -> strokeWidth
You did not declare i with var
While straightforward, your code has no comments at all..