My Scout unicycle group has a Semcycle XL 2-Wheeler which we cannot adjust
properly. The bottom wheel moves off onto an angle, and the tires slip off
to the side. I have replaced the 1.75 tires with 1.85 primos. Any help
would be appreciated.
John Hooten
Greetings
In message “multi-wheel unicycle problem”, John Hooten wrote…
>My Scout unicycle group has a Semcycle XL 2-Wheeler which we cannot
>adjust properly. The bottom wheel moves off onto an angle, and the tires
>slip off to the side. I have replaced the 1.75 tires with 1.85 primos.
>Any help would be appreciated.
I don’t know about the Semcycle but in general with 2-wheeler you should:
>John Hooten
>
Stay on top, Jack Halpern, IUF Vice President Website:
http://www.kanji.org
> My Scout unicycle group has a Semcycle XL 2-Wheeler which we cannot
> adjust properly. The bottom wheel moves off onto an angle, and the tires
> slip off to the side. I have replaced the 1.75 tires with 1.85 primos.
> Any help would be appreciated.
I would recommend sending this question directly to Semcycle, in case
nobody from the company is listening here. They must have encountered
this before.
Based on the simplicity of the design, imperfections probably creep in if
the tolerances are slightly off in the bearing holders. A simple solution
might be to put some shims in on the offending side, to bring the wheel
back into line. I have not tried this.
Good luck, John Foss, the Uni-Cyclone jfoss@unicycling.com
www.unicycling.com
“Someone who thinks logically is a nice contrast to the real world.”
John Foss wrote:
>
> I would recommend sending this question directly to Semcycle, in case
> nobody from the company is listening here. They must have encountered
> this before.
Or call Paul at Osells Custom Cycles (612-788-5200) as I remember him
talking about fixing a couple of the semcycles that had that problem.
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========================================================John Hooten <jhooten@rcsis.com> wrote:
>My Scout unicycle group has a Semcycle XL 2-Wheeler which we cannot
>adjust properly. The bottom wheel moves off onto an angle, and the tires
>slip off to the side. I have replaced the 1.75 tires with 1.85 primos.
>Any help would be appreciated.
The two wheels must be held in exactly the same plane. Otherwise, the
centers of the wheels will be pulled apart, one wheel to the left and the
other to the right until they slip as you experienced.
I’ve built a number of two wheel unicycles. They all had a bottom axle
slot that was 7/16" wide so the 5/16" axle could be moved 1/8" front to
back on both the right and left sides. With just the right adjustments, a
slightly out of true frame can be compensated so the wheels are in
precisely the same plane.
A practical test for whether both wheels are in the same plane is to place
the unicycle up side down on its seat. Turn the pedals forward and observe
whether the wheels pull away from each other in a side-to-side sense. Do
it again, this time turning the pedals backwards. If in both instances,
the wheels track each others center without pulling to either side, the
wheels are in the plane. If not, loosen the axle a bit and twist the
bottom wheel to match the plane of the top wheel and retighten the axle
and repeat the test.
I haven’t seen a Semcycle XL 2-wheeler, so I don’t know if or how such
wheel plane alignment can be adjusted. Hopefully it has wider than normal
axle slots like the two wheelers I built, so the adjustment method above
can be used. If the slots are too narrow, one could apply a rattail file
in the appropriate spot, making the slot wide enough for the needed
adjustment. When filing the slot, be sure the gripping washer has enough
metal to grip and be sure to leave enough metal so the entire slot area in
structurally sound (in either case don’t file too much!).
Sincerely,
Ken Fuchs <kfuchs@winternet.com
This refers to John Hooten’s post of a few weeks ago about a Semcycle
two-wheeler with badly aligned wheels resulting in slipping. I mentioned
the issue to someone from Semcycle I saw today. He recommended in general
that the bottom tyre be pumped quite hard (as it takes your weight), and
the top tyre not harder than needed to prevent slip. That way, the top
tyre would fold slightly around the bottom tyre, and also the top tyre
would be more flexible to absorb and “correct” some lateral slip without
accumulating in too much sideways movement and consequent run-off.
“To trigger/fool/saturate/overload Echelon, the following has been picked
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