frame size question...

No.

Not necessarily.  If you can test ride something that's very similar w/ regards to the geometry of a used bike you may be looking at, then it would be fine.  Unfortunately there is no 'standard' between brands, so what would be a 58 in one brand may be a 'large' in another or a 56 in brand x might fit you better than brand y.  It's all going to come down to what fits you best.  No one can give you a definitive answer because of that.

I ride a 60 cm road bike and a 61 cm tri bike.

But I think my road bike is the wrong size.

Depends.

Cervelo does a very good job of "equalizing" fit coordinates so their size names are roughly comparable. That said, there are pro team cyclists who ride a 58cm Cervelo road bike, but a 54cm time trial bike- Cervelo discussed that at one of their "Brain Bike" dealer symposiums.

Ultimately, size names are arbitrary. If you visit your LBS and line up three different brands, each in their so-named "54cm" frame size, then try to make some systematic comparison of the seat tube dimensions you'll see some pretty significant discrepencies in their actual measurements. A 54cm Cervelo will measure about 51cm from center of bottom bracket to top center of seat tube, while a Felt may be exactly 54cm and Quintana Roo something else entirely.

The industry does this for a few reasons, not the least of which is to compel you to rely on your local dealer for fit services, a not entirely subverssive agenda.

In the end, you need a decent fitting by a formally trained (in triathlon fit) F.I.S.T. Certified triathlon bike fitter. I prefer a lad or lass who has done triathlons themselves. It will cost you- a few hundred bucks likely- and it will be worth about what you pay in saved time, enhanced performance and potential discomfort avoidance. Also, there is something to be said for getting on the right equipment from the onset- there is a true value to that.