I'm trying to figure out how to steer an in-line wheel scooter. The
wheels must be in line and close together in order to smoothly
traverse rough terrain.

So far, apparently that's by making the wheel frame flexible.

Here are some very simple stick figure drawings (included both BMP
and JPG of the same thing):

Newsgroups: alt.binaries.phish
Subject: in-line scooter drawing

The bar extending forward has to be flexible and strong. Whether or
not it is a viable steering device will be determined. There will
also possibly be some leaning to one side or the other involved when
the bar is twisted left or right, maybe riding on either the left or
right row of wheels. There are some functional complexities involved
having to do with carving/turning and control of that action like on
in-line skates and maybe other recreational devices. Ideally the
metal will flex to a point and then resistance to flex will increase
greatly. I guess that's the way most spring steel does? Or will it
just deform? Maybe that's how a tension bar works (multiple layer
flat bar steel)? Although I doubt that could be used. There might be
some serious jarring pressure on the metal bar, so having a flexible
and strong enough is necessary but might be difficult to achieve.
The shorter the stronger, but that also means less flexibility.
Fortunately, that piece of flat bar extending forward is easily
replaced for trying various 1/8" thick metal bar.

There might be other solutions if this one doesn't work. The goal is
to turn an in-line set of wheels efficiently using a simple design.

Thanks.