here is something i found at
http://laneshare.org/ca.htm
The generally “understood†guidelines seem to be:
Travel no faster than 10 mph faster than the vehicles you’re lane-sharing with.
Merge back in with the traffic when they reach 30-35 mph.
Never exceed the speed limit.
Lane-sharing between lanes #1 and #2 is preferred. (#1 being the “fast†or “inside†lane)
Stay, more or less, in one lane or the other. Excessive meandering might get you cited. (CA code 21658)
Add to this a few other pointers:
Be a competent rider before attempting the practice.
Be prepared to adjust your speed as necessary.
Cover your brake and clutch to reduce reaction time.
Avoid lane-sharing between two large trucks.
Be wary of open spaces inviting a vehicle to change lanes.
Be vigilant of other vehicle operator’s head movements indicative of an impending lane change.
Check your mirrors and be prepared to move over for overtaking motorcycles behind you.
When in doubt, wait for a CHP motor patrol officer and follow him/her. (You might have to travel a bit faster than 10mph to keep up.)