Adjusting shock preload on Honda and yamaha

How to adjust shock preload. My wife is a smallish lady that rides a huge Yamaha raider. She was coming clean off the seat when she would hit a big bump. I am a huge guy on an average Honda motorcycle and it was bottoming out when I hit big bumps. I fixed both these problems by releasing some of the spring preload on her bike and adding spring preload on my bike. There is a way to measure travel and sag and adjust the preload to approximately 30 percent of that travel, but I’m going to just move it a little at a time until the ride is satisfactory for both of us.

As an affiliate for the links below, I get a small fee or commission if you make a purchase.
My website https://bcblades.net/
Amazon https://amzn.to/3DqKTaP
Combat Abrasives https://bit.ly/3mFIWRL
Renegade products https://bit.ly/3ssp9Go
Maverick Abrasives https://bit.ly/3kxAyBp
Donate https://www.paypal.com/donate/?business=JAX9BNBWK49PE&no_recurring=0&currency_code=USD