Wheel wobble isn't a machine thing, it's a rider thing.

Obviously, there has to be a certain amount of side to side movement of
the wheel to maintain balance, but people do ride 20s and Cokers on very
narrow strips: kerbstones, log bridges, bridge parapets...

I think wobble happens when your pedal action isn't smooth. If you
pedal in a series of hard downwards pumps on the pedals, the uni will
tend to turn towards the pedal which is going downwards. If you pedal
smoothly and fast then you will travel in a straighter, smoother line.

I think crank:wheel ratio matters a bit. I put 170s on the 26 and found
it was quite difficult to avoid the "push push" style of pedalling,
rather than the "spin spin" style. The uni was slow, the tyre
introduced an element of weave, and I couldn't keep the pealling smooth
enough. On the other hand, I never notice weave or zig zag on the 28
with 110s.

It also seems to be the case that a larger diameter wheel weaves less.
I think that's an absolute, because (unless you scrub the tyre) the
uni's turning circle is dictated by the wheel diameter.

And the Coker seems to be almost a 'special case' because the wheel is
so big and heavy that you don't pedal it, you let it spin, and just pump
a bit more energy into it. It works like a flywheel or gyroscope.


--
Mikefule - Roland Hope School of Unicycling

The long distance Fule on his farcycle
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