I'll be working in Bellevue for 2 weeks this month, and one week in mid-July. I doubt I'll fit a bicycle or helmet on the plane, but I'm still curious about bicycling locally for transportation. Depending on auto congestion and bus service, a cheap bike on CL might be interesting.

(a) Bike Lanes - mandatory? Useful??
Is bike lane use required by law or enforced by motorists? Are bike lanes built well enough that bicyclists use them voluntarily?

(b) Helmet laws
How(If) is helmet use enforced? Depends on officer's mood? Used to hold bicyclists responsible for all injuries if they are not helmeted?

My experience with bike lanes from MD - NY is mixed (a few well designed, some completely unusable), but I haven't been to Seattle yet.