Several ghost bikes have been installed in the Santa Cruz area. Many have been removed.
From the Santa Cruz Sentinel:

A mass of bike-riding mourners remembered a teenage cyclist who died in a bike crash near East Cliff Drive on Jan. 2.
Lucian Gregg's friends, family members and former teachers, as well as members of the cycling community who never met the 18-year-old, participated in the Saturday afternoon memorial ride. The pack of bicycles sometimes stretched for the length of a block as they made a leisurely loop through downtown to the site of the fatal crash.

Read more here.
The ghost bike left in honor of this cyclist has been removed.