Of course, there was nowhere thereabouts to

buy a set of scales, and by now all the people on

the TV crew who’d come to film the thrust test

were looking at me and smiling. There were

houses close by and there was probably a set

of scales in every bathroom in every house.

All I had to do was go and ask someone. Can

you imagine someone turning up on your

doorstep in the middle of the afternoon and

asking to borrow your bathroom scales? The

TV crew love it when I have to do something

like that. I’m sure they all get together before

each shoot and say, ‘Right – who’s got any ideas

for something really stupid that we can we

get Guy to do this time?’ I don’t really mind.

They’re a great bunch and it’s all part of the fun.

As it turned out, the gentleman in the first

house that I went to was more than happy

to lend us his bathroom scales, we strapped

Above: Fitting the rear wheel prior to testing the tyres
on the Tamar slipway.

them to the test rig and they worked just fine.

Graham and Charlie had worked out that the

overall weight, with me at around 75 kilograms,

the bike at around 110 kilograms, and a bit

added on to account for the fact that I would

be soaking wet and that we were bolting extra

bits to the bike, meant that the planing surface

would have to generate lift of roughly 200

kilograms. For it to do that, they calculated that

we would need at least 50 kilograms of thrust

from the rear wheel.

We tried the knobbly tyre first, dipping it into

the water to different depths to see how that

affected its performance. The answer was that

new tricks for a magic bike   157