That seem more metaphorical, doesn't it?
It's like going through a series of repeated activities that are quick and/or confusing(fast, painful, soothing) until you reach the end(climax) of the ride.
I don't think you're suppose to sub it, it's a feeling I guess?
If I was subbing it I would say something similar and move on. For example, "It's like a merry-go-round!"
--Or you could try to find something that means "reaching/approaching climax".
--Or make a note in the sub and give a small hint to it. Sometime I add something like that but its most comical.
WHATEVER YOU DO... DO NOT OVER THINK IT.