So, billh, if a bike lane would slow me from 35 to 30 mph, are you saying it should not be built? If not, what speed differential is too much (you can use the chart below as a guide to answer)? It sounds like you might be arguing that the government shouldn't stripe a bike lane unless the lane is built and maintained perfectly. If that's your standard, maybe we can agree.
But, assuming that's not your position, it's now time to answer the other question. Assuming a non-ideal bike lane is built or an ideal bike lane is not ideally maintained (we're in the real world here), and that riding safely in it as opposed to riding in traffic would slow down cyclists. Under which of these circumstances should it be legal for a cyclist to leave the bike lane?
Safe traffic speed 35mph, safe bike lane speed 30 mph
Safe traffic speed 35mph, safe bike lane speed 25 mph
Safe traffic speed 35mph, safe bike lane speed 20 mph
Safe traffic speed 35mph, safe bike lane speed 15 mph
Safe traffic speed 35mph, safe bike lane speed 10 mph
Safe traffic speed 35mph, safe bike lane speed 5 mph
Safe traffic speed 30mph, safe bike lane speed 25 mph
Safe traffic speed 30mph, safe bike lane speed 20 mph
Safe traffic speed 30mph, safe bike lane speed 15 mph
Safe traffic speed 30mph, safe bike lane speed 10 mph
Safe traffic speed 30mph, safe bike lane speed 5 mph
Safe traffic speed 25mph, safe bike lane speed 20 mph
Safe traffic speed 25mph, safe bike lane speed 15 mph
Safe traffic speed 25mph, safe bike lane speed 10 mph
Safe traffic speed 25mph, safe bike lane speed 5 mph
Safe traffic speed 20mph, safe bike lane speed 15 mph
Safe traffic speed 20mph, safe bike lane speed 10 mph
Safe traffic speed 20mph, safe bike lane speed 5 mph
Safe traffic speed 15mph, safe bike lane speed 10 mph
Safe traffic speed 15mph, safe bike lane speed 5 mph