Just some spontaneous info for ya.......
Sometimes vehicles will ONLY obtain top speed in 5th gear. The only way to push through the wind is with power and the high RPM of 5th will push the vehicle through the wind better than shifting into sixth. This is not all cases and have a ton of variables but is still a reality in some cases.
As it goes for an R1 with an exhaust doing 189 mph..... I say it is probably possible however with the gearing you would have to use, you would have to have your buddy push you and the bike up to about 26 miles before the bike took over and bogged it's way through the gears
A friend of mine held the fastest partial streamlined motorcycle record. He took his turbo busa (that he rode to work) up to 246 Mph at the salt flats.
He said that the issue with going any faster was the fact that his swing arm was bending at 230 and it was hard to control hahahahahaha!!!!
He said the bikes starts off with normal steering (steer left - go right, etc), then at about 210 the front wheel began to work like an airplane rudder and the bike would steer left go left. Then at about 230 it would go back to conventional steering because of the down force over taking the wind.
Makes ya kind of chuckle when we talk about going 155mph

LOLOLO