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Like someone said, the top of main street is a shitshow of a rotary/circle with lights. Would not work well with a group. For a place to stop and make sure everyone's bike is good to go I would suggest take a right onto 101e then take the left onto optical ave. A few seconds after you make that turn there are huge Timken parking lots on your right and a huge Markem parking lot on your left.
If gas is needed by or before this point there's a pretty big Sunoco? with plenty of parking in Troy.
-Evan