sorry if this is a repeat thread, i did a couple searches but had a tough time finding the info I am looking for. How do i determine what size derailleur I need (ordering on line, clamp on, options are 32 and 35 mm). Thanks in advance for the help.

There are two easy methods to figure out the ST diameter. Assuming you don't own calipers, how about an adjustable wrench? Adjust to the size of the ST and measure the opening with a scale. The other option is to wrap paper around the ST, mark the point of overlap, then unroll the paper, measure the length and divide by 3.14. The 32mm will measure about 3-15/16 inches and the 35mm will measure 4-5/16 inches.

wow, didn't even realize that that is what i was measuring for. total brain lapse moment. thanks a lot for the help.