Our triathlon will be this sunday and it is now friday night. As I was test riding my bike tonight I noticed that the rear derailleur was shifting funny. It would shift but slip to another gear. So, I tried adjusting the barrel and it seems fine but not too confident about my work(Gear not slipping after adjustmen.) I callled the bike shop that would be conducting the race packet pick up and explained my situation and they said to bring it in and they will inspect it. Should I go with my insticnt and ride or have it checked just incase. Not sure about tinkering with the bike the day before race day. Need your opinion. Thank You in advance

sometimes things just stretch or need adjustment. if it works after your adjustment I say just do the tri and save your money. Watch a tutorial about derailleur adjustment on bicycletutor.com or something. Trust me you can do your own bike work it's not that hard.

edit: i looked at the post date and realized my advice is a little too late for your specific tri, but I stand by it. Hope the tri went well.
-durty