Follow the Adventure Cycling route 1 to 101. There are state parks at Gaviota, Refugio & El Capitan. There is one dicey bridge but it is short, well marked, with good sight line & warnings to cars to look out for bicycles. I have ridden this route several times & consider it perfectly safe.
If safety is a concern, DO NOT take the 246/154 option. It has a steep long uphill to the top of San Marcos Pass, with a fast, steep descent on a narrow road down to Santa Barbara. It is a shorter alternate between Santa Barbara & the Santa Ynez Valley & tends to attract people in a hurry. Plus the coastal route is more scenic.
dougP