What do you tell a client that wants to bring in their road bike to get fit for a tri bike (using their clip ons?).

I do not have a fit bike.

Do you tell them no, recommend them to a fitter with a fit bike, have them borrow a tri bike in their size to fit on, or explain that the road bike measurements with clip-ons may get us close, but it's not the best option and let them decide?

Thanks for your input.

Denise