I examined some closeup pictures I took of George Peck’s unicycles when he was
at the NUM and UNICON last summer. It seems he uses a skinny alloy rim with fat
MTB tire. I recommend going with what George uses, because he’s the expert, and
has tried all kinds of different parts.
Next time you go to your bike shop, you can mention to the smart people there
that there’s no such thing as a unicycle rim, at least to my knowledge. Hubs and
tires yes, but not rims.
John Foss closet MUnicyclist coiner of the phrase “UMX” oh, I guess I also won
the event at UNICON last summer unicycle@aol.com
I got my MUni together today and took it for a test ride at the local
college campus. The wheel consists of a 26" Mavic 231 rim, Performance ATX
26 by 1.9" inverted tread tire attached to a Semcycle Deluxe hub by 36 14 ga
DT stainless steel spokes laced 4-cross. The frame is a 28" Semcycle frame,
with an old-style Schwinn seat. The cranks are aluminum 170mm bicycle cranks
with the spider ground off the right arm. The pedals are BMX style platform
pedals made by GT bicycle, modeled after the extinct Shimano DX pedal.
I was immediately impressed with how slowly and easily I was able to climb
the very first curb I came to. Of course it helped that my pedals were in
just the right position to power up and over. On my 24" uni, with its 5.5"
cranks, I'd have had to rely on speed and perhaps a little rolling hop to
bump me over it, but I rode up to it slowly until my tire touched and then
just pushed down on the lead pedal.
After becoming somewhat familiar with the larger wheel and longer pedal
stroke, I rode diagonally down a series of 10 or 12 steps, 18" long and 4"
high. I spent some time trying spins, one-footed idling and hopping on
level ground, and hopping sideways up the same steps, with varying success.
It hops well, partly I think to the large volume of air in the tire and
partly due to the lightweight alloy rim. Takes bumps noticeably better than
my 24" too.
I still have some dialing-in to do with the frame, clearances between the
hub flange and the inside of the bearing clamps are extremely tight. I had
to file down the bearing clamps because they scraped on the hub flanges. I
had to dimple the inside of the fork blades slightly just above the bearing
clamps so the spokes running over the outside of the flanges would not rub.
You see, the Semcycle Deluxe hub axle has no shoulder built in to locate the
bearings, instead collars of varying thickness are machined to slide over
the axle and hold the bearing out from the flange. Tom Miller was very
helpful in making what he guessed to be the correct size collars but I think
I'll ask him for some about .025" thicker.
Overall, I am extremely pleased with the results. I believe this will become
my preferred street uni, but I am still looking for some of the old style
crankarms with no lateral offset. I find that the pedals are an extra inch
or so further away laterally from the centerline of the axle and this adds
some strangeness to the feel of turns and twists.
The DX pedals have a smooth surface, but come equipped with holes for up to
10 studs, much like the studs in automobile studded snow tires. The pedals
came with 6 studs installed in each side of each pedal and they are almost
too grippy. When freemounting, I rarely get my foot on the pedal exactly
right and I spend several revs trying to lift each foot and set it down
again in the proper position. Each stud sticks up about 3 millimeters, so I
will probably grind them down to about half that height and maybe round off
the tops too.
(In response to the post by D. Kathrens about his MUni):
You will be very unlikely to break unicycles as fast as George Peck does. He
seems to be an expert at this. He does a lot of hopping, and approaches his
riding as an aerobic workout; measuring heart rate and elapsed time. Who knows,
maybe you’ll be more abusive than him? We don’t know.
The hubs he uses are stronger simply due to their greater size. I don’t know
offhand, but the axle diameter is a lot thicker on the Phil Wood axle, and
that’s what makes the difference. Don’t know where you can get crank arms.
I’m facing a similar problem (building a new unicycle). Though I ride a fairly
“stock” Miyata/Semcycle combination, I broke my Miyata frame last summer, and
want to replace it with something more substantial (yet still rigid, unlike a
Semcycle or Schwinn). I may go to a custom frame builder somewhere in my end of
the country, or have something built by the guy who builds for George Peck. My
main problem is how to pay for it. This project will have to wait a while.
I hope you’ve seen enough of your local bike mechanic to not bother with him any
more. Some people just aren’t comfortable working on unusual things, but in his
case he sounds fairly incompetent. I’m not a bicycle mechanic myself, but I read
BICYCLING MAGAZINE and a few books, and I know the only hard part about making a
custom wheel like yours is figuring out what length of spoke to use.