and then gravity will be the main force acting
on it, pulling it down until the wheels touch
the road.

A motorbike hydroplaning across a lake has to

deal with all of those forces, and keeping up the

forward thrust is clearly the key to maintaining

that ‘Third Law’ pressure that will keep the

front wheel hydroplaning. And so is shifting

as far back on the saddle as you can go. Hugh

had no doubt that this was a major factor in

achieving a successful motorbike hydroplane.

The less weight there was on the front wheel,

the better. The whole thing was a balancing act,

balancing forward thrust against gravity and

drag as well as balancing the attitude of the bike

to keep the front end up on the surface.

Keeping the bike at the right angle was also

going to depend on hitting the water at the right

angle. The impact with the water was a crucial

factor in making the bouncing bomb skim across

the surface. Skimming a stone also shows you

that. If you get down low in order to give the

stone as flat a trajectory as possible, you get far

better results. The bouncing bomb, like

the skimming stone, was also spinning.

The spinning gave the bomb what is called

gyroscopic stability. To try to understand how

that works we have to go back to Newton’s

First Law again. The bomb would tend to carry

on spinning at a certain angle – parallel to the

surface of the water – and this helped to stop

it from toppling over and going off course as it

bounced on the surface.

I would have spinning wheels on my

hydroplaning motorbike, of course, but because

they wouldn’t be spinning freely – they would

be churning through the water – they wouldn’t

provide me with any stability. All gyroscopic

bets were off in that respect. Hugh also pointed

out that I would have another problem with

balance when the wheels left firm ground and

hit the water. Without the grip that the tyres

provided on dry land, I would need to draw

deep on my motorcycling experience to stay

upright. He described how it would be like

trying to stand on a tea tray in a room where

the floor is covered with marbles. I wasn’t too

worried about that. If the guys on the internet

could manage to stay upright, then so could I.

Though I might not be too confident balancing

on marbles while standing on a tea tray, give me

a motorbike and I’d fancy my chances.

KEEPING YOUR END UP   147