You can use scales if you care about a number, or you can just do it by feel on the hands. Any good fitter will have this discussion with you when you talk about your objectives for your bikes, especially if they are fitting multiple bikes with different positions for various road/cross/gravel disciplines. Its pretty easy to feel the differences, and if you have a chance to get a guru dynamic fit they can run you through a range of these fit parameters in real time to try to achieve the best balance for your riding style and position requirement.The fast road bike has less setback and more weight on the hands because the stem is slammed compared to my cross bike for example where the position is more upright and optimized for technical handling.