Where I live (New South Wales, Australia) the official way for cyclists to traverse junctions like this is to stop/slow down about where the back of the red car is, do a 90 degree turn to the right and cross the on-ramp - either cycling or walking - perpendicular to the direction of traffic, then get going again down the "far" side of the on-ramp (from the perspective of this image.)

Not perfect because unless there's nothing coming down the ramp at all you still have to slow down/lose momentum if not actually stop, but definitely preferable to becoming a human zipper between two lanes of merging cars travelling three times faster than you are.