bike lane interuptions
You don't say where in the world you are, so it's not clear what the traffic regulations are. I'm in the UK, so I'll assume UK-like regulations&nbsp;&ndash; bicycles are allowed to use the vehicle lanes even when there's a cycle lane and bicycles are basically supposed to act like cars.

First, regardless of regulations, you've missed option&nbsp;3, which is to slow down to a speed where the cycle lane is usable. You don't say exactly what the problems with the cycle lane are but, unless they're so dangerous that the highway authority needs to have fixed them yesterday, you should be able to slow down for them. By approaching what you know to be bad sections of the cycle lane at speed, you are severely limiting your options.

Second, you mention motorists being surprised when you enter their lane. In jurisdictions that I'm familiar with, signalling a turn means "I intend to manoeuvre when it is safe to do so." In particular, it does not mean "Please make space for me&nbsp;&ndash; I'm gonna turn!" If you are signalling, it would be nice for somebody to make space for you, but that is not an obligation and a car rapidly braking from its 40mph to your 20mph is asking to be rear-ended. If your lane change is causing surprise, it suggests that your manoeuvre wasn't safe and that you were using your signal as a request for space rather than a notification of intent. After all, if there had been enough space for you in that lane (i.e., a long enough gap in the traffic), motorists wouldn't have had to react to your presence at all.