Re: odd uni idea
Dennis Katherns <d.kathrens@genie.geis.com> wrote:
>I want one really bad and I had the same idea as you, find a Schwinn replica
>penny farthing. Tom could build me a custom big wheel uni if I give him about
>$500, but that’s not going to happen any time soon.
>He told me how he made his first ones, back in his high school days. He made
>his own hubs out of small kids-bicycle chain wheels by cutting the teeth off
>and drilling spoke holes around the circumference. He welded two of these to a
>steel bar 5/8" in diameter and filed flats for cottered cranks. The spokes were
>simply lengths of steel wire with spoke threads rolled into one end and a
>“dogleg” bent into the other end. The rim was made by cutting and carefully
>uncurving two or three 26" steel bike rims and weld- ing them together. The
>tire tread was simply a bulk length of wheelchair rubber held on by an internal
>wire and glue. The frame was easily made Schwinn-style with two pieces of flat
>bar stock.
Back in 1980, Tom helped me put together a 40" big wheel right after he finished
his duties as the 1980 National Unicycle Meet Director! In the few years
thereafter, I put together close to a dozen big wheel unicycles in sizes from
34" to 56", using Tom’s basic design and a local machine shop to do the frame
and weld the rim pieces together.
Hub flanges can be made out of 16-18 gauge 5" disk plates with 5/8" hole in the
center for the axle. I had a jig made so the spoke holes could be drilled at the
exact same radial distance. A paper plan of where the spoke holes should go can
be taped over the top plate and drilled into with a drill press. After the holes
are drilled, a de-burring tool can be applied to each side of every spoke hole.
The axle must be made of cold rolled steel so it will be hard enough to last a
long time, but if it is too brittle the axle can crack or break. It would be
best to find out exactly what axle material Tom uses. It is easiest to cut
notches for cottered cranks in a mill. Be sure the flange spoke holes are
staggered properly before welding them on the axle. After the flanges are welded
to the notched axle, they can be painted a silver, aluminum or chrome-like color
or actually chromed.
3/32" x 36" stainless steel welding rods make excellent spokes with an old
bicycle style S end on one end and 3 56 cut threads on the other end. This
makes very close to a 13 gauge spoke. 13 gauge nipples are somewhat hard to
find, but are available. Schwinn had a big supply of these. Now Semcycle
might have a supply of these or may be able to make a referal to a parts
supplier who does.
27" x 1 1/4" Schwinn tubular rims are excellent raw materials for making big
wheel rims by cutting at the spoke hole and slowly increasing the radius and
matching to a circle of the desired wheel size on a large sheet of cardboard.
Using 36 hole 27" rims, the possible big wheel rims are:
No. of Holes Wheel size in inches (approximately +/- 0.25") 48 34.25" 52 37"
56 39.75" 60 42.5" 64 45.25" 68 48" 72 50.75" 76 53.5" 80 56.25"
Wheel size above includes a total of 1" wheelchair rubber, 1/2" sticking out on
either side of the rim, so outside diameter rim measurements will be 1" less
then the size given in the above table.
Use the hardest grey wheel chair rubber in the 7/8" diameter size. Use 11 gauge
steel wire inside the wheel chair rubber. A gapping tool is placed between the
ends of the rubber to keep them apart while the wire is tightened until the wire
makes a somewhat high pitched sound when picked. Twist the wheel 180 degrees in
the direction that causes the wire ends to wrap around each other. Cut the wire
carefully to the length of the gapping tool; make sure the wires don’t unwrap
until the gapping tool is removed and the rubber ends can be pushed around the
wrapped wire ends. WD-40 or another light lubricant is used to get the wire
through the hole in the tire and to slide around the rim. The rubber should be
cut 12-16" longer (depending on wheel size) than the circumference of the wheel,
so the compressed rubber will close up the gap between ends and also so the ends
won’t separate during normal use of the big wheel.
This was not intented to be big wheel build it yourself guide, but it has gotten
close to it in some respects. Just wanted to add enough information for any
would be big wheel builder to seriously consider building one. It’s not that
hard to build a big wheel to equal the quality of one built from a penny
farthing replica!
Stay on Top,
Ken Fuchs <kfuchs@winternet.com