Newb from PNW (inland)

Welcome to the forum. I am from the Cd'A area and have witnessed many 70.3 and 140.6 IMs here in town both as an athlete (70.3) and a volunteer. In the 70.3 you will see everything from a mountain bike or two to road bikes with clip on aero to tri bikes. In the full IM you will see some clip on aero on road bikes but also predominantly tri bikes. What you choose depends on your budget and on what your goals are: Bucket list finish or going for front of the pack in your age group.

I will never have a tri bike but am comfortable with my road bike with aero bars. I'm a 60-something (on the downhill slope toward 70) who simply wants to do and finish these races.

Hope this helps.