The Coast to Cardiff. 35 mi, 1740 ft el, 48 ft/mi

0.0 R San Marcos
2.5 = Palomar Airport
8.8 R ramp to S Coast 101
23.8 U Cardiff State Beach -
Break beach
25.4 R Poinsettia
26.0 L Paseo Del Norte
26.4 R Camino De Las Ondas
26.7 L Hidden Valley
27.0 L Plum Tree
27.0 L Hidden Valley
27.6 R Palomar Airport
32.5 = San Marcos
34.1 R Discovery
34.4 L Discovery
35.1 L Via Vera Cruz
35.5 L OCRR

Super simple route, with lots of beach views.
Good for hot summer days.