Hubs and Tires

Unicycles and Equipment
1

Couple quick questions:

Does anybody have any opinions on whether the sem deluxe axle is better than
the miyata axle? I’ve heard it go both ways. But I think Geoff Faraghan put
the Sem axle on the Telfords. Any takes? I broke another axle on my
freestyle machine.

Does anybody know if a 3.0" Gazzaloddi tire will fit in the Pashley frame? I’m
pretty sure it won’t, but it’d be neat to try if it would fit. How about the
2.6" tire?

That’s all the questions I have for today. Maybe tomorrow I’ll realize that I
don’t have any money and I can’t get this stuff anyway.

Its been real, Brett “Bloodman” Bymaster aka “dude” “Please whatever you do,
don’t fall off”

2

RE: Hubs and Tires

> > Does anybody have any opinions on whether the sem deluxe axle is better
> > than the miyata axle? I’ve heard it go both ways. But I think Geoff
> > Faraghan put the Sem axle on the Telfords. Any takes? I broke another axle
> > on my freestyle machine.

Geoff seems to think they are about equivalent. A standard Telford comes with a
Suzue Miyata axle. The stronger option is the re heat-treated Semcycle axle,
which is $100 extra and definitely way stronger.

This heat treating is based on a specific batch of Semcycle hubs that may not
have had the complete heat treating job they were supposed to have had in the
first place. My experience with Semcycle axles from many years ago was that they
were much, much stronger than the Miyatas. But since both companies continue to
make changes in their products, it’s hard to be sure what you’re going to get,
unless the makers would like to give us some more detail.

> > Does anybody know if a 3.0" Gazzaloddi tire will fit in the Pashley frame?
> > I’m pretty sure it won’t, but it’d be neat to try if it would fit. How
> > about the 2.6" tire?

Remember, you would need a 24" tire, plus the double-wide rim; a pretty big
investment. I’d try the 2.6 first. What a difference! I have it now on my DMATU,
and at MUni Weekend I was able to hop up things I couldn’t hop before, and ride
down things I was scared to before. Now I just need some longer cranks! Though
the 3.0 would probably make the ultimate snow tire for Indiana’s winter, I think
you’ll get great results with the 2.6 as well.

> > That’s all the questions I have for today. Maybe tomorrow I’ll realize
> > that I don’t have any money and I can’t get this stuff anyway.

Poor Brett, the poor college student. Hope your studies are going well, and
that you’re getting out for some fresh air at least once in a while. We all
miss you here.

If it makes you feel any better, it rained all last night. Yuck, summer’s
definitely over!

Stay on top, John Foss, the Uni-Cyclone (reply to jfoss@unicycling.com)
http://www.unicycling.com

“I’m okay, I crash like that a lot.”

  • Dan Heaton
3

Re: Hubs and Tires

I have ridden both the NK hub (Sem deluxe) and the Suzue hub (Miyata) on my
twenty four inch Schwinn. It all started when I bent the Schwinn hub. Schwinn
was less than concerned about the situation, but finally I got in touch with Tom
Miller who recommended the Suzue, but said that everyone else thinks the NK is
better. I tried the NK first, and snapped one in four weeks of rugged MUni
riding. The second one took six weeks to snap. Since then I have been riding the
Suzue, for about a year, and have not been able to break one, despite learning
to hop on them.

I do however constantly wear out the crank seats and I am in the habit of
replacing the hub when I replace the cranks, as the fit seems to last longer.

The NK hub sells for about 45 dollars, unless you have a broken one from an
unmodified Semcycle unicycle to trade in. The Suzue hub sells for 20 or 25
dollars. You can buy two Suzues for the price of one NK.

The last time I talked to Geoffry Faraghan, he was using the Suzue for his
standard wheels and a heat treated version of the NK for the optional stronger
wheel. The heat treating probably eliminates the brittle part of the hub that I
was snapping. I am told the NK flange assembly is spin welded to the axle, and
while that might make a strong joint it would also tend create a lot of heat and
ruin the temper of the axle. I am guessing at this point so I stop now.

I recommend the Suzue, unless you can buy the DN.

I would bet that John at The Unicycle Source would know how big a tire you could
fit on a Pashley

Joe Stoltzfus

4

Re: Hubs and Tires

>The last time I talked to Geoffry Faraghan, he was using the Suzue for his
>standard wheels and a heat treated version of the NK for the optional stronger
>wheel. The heat treating probably eliminates the brittle part of the hub that I
>was snapping. I am told the NK flange assembly is spin welded to the axle, and
>while that might make a strong joint it would also tend create a lot of heat
>and ruin the temper of the axle. I am guessing at this point so I stop now.

Doesn’t heat treating makes steel both stronger and more brittle?

Sincerely,

Ken Fuchs <kfuchs@winternet.com>

Microsoft has finally found someone it can’t bully into submission: US
Department of Justice - http://www.usdoj.gov/atr/cases/ms_index.htm Yahoo links

5

Re: Hubs and Tires

Ken wrote:

> >The last time I talked to Geoffry Faraghan, he was using the Suzue for
his
> >standard wheels and a heat treated version of the NK for the optional
stronger
> >wheel. The heat treating probably eliminates the brittle part of the hub
that
> >I was snapping. I am told the NK flange assembly is spin welded to the
axle,
> >and while that might make a strong joint it would also tend create a lot
of
> >heat and ruin the temper of the axle. I am guessing at this point so I
stop
> >now.
>
> Doesn’t heat treating makes steel both stronger and more brittle?

I hope someone can give you a fuller answer to this, as I find this difficult to
explain Ken but basically heat treatment re-aligns the structure of the steel.
What effect that has depends on the temperature achieved, the method of cooling,
the length of cooling and several other factors. It can make a material harder
and more elasticity. Strong is not an engineering term.

How often a hub brakes depends on lots of factors including the distance over
which the torque force is applied, if there are any stress raisers (generally
and sharp edges), the elasticity and hardness of the material, and etc.

Roger

6

Re: Hubs and Tires

> Doesn’t heat treating makes steel both stronger and more brittle?

In the sense that stronger means that it would take a larger load before
failure, then that is correct.

I’ll take a stab at trying to explain it (though I am not an expert about it):

Heat treating steal will make the yield strength increase by about 3 times
depending on how it’s done (and the type of steal). The yield strength is the
amount of load it can take before plastic deformation occurs (for ductile
materials) or until fracture (for brittle materials). Both ductile and brittle
are relative terms to each other. A typical higher quality steal that has not
been heat treated will plastically deform before failure which means that for
the case of a unicycle hub, the hub will be bent before it fractures. For the
same steal that has been heat treated, it will not plastically deform (or at
least not as much) before it fractures, but will just snap when the maximum load
has been exceeded. The maximum load for the heat treated one will be higher than
for the one that wasn’t. However, for some applications, plastic deformation is
a good thing, but not really for a unicycle hub (though if you’re miles away
from your car out on a trail, you’d probably rather have a riddable bent hub,
than a fractured one for when it does fail. That’s the cost of having a longer
lasting hub.).

What does heat treating do? It recrystalizes the atoms of the material into a
different crystal structure. Steal starts out as BCC (body center cubic) and can
be heat treated into others like BCT and FCC, or a combination of those. This is
done by heating the metal past a certain point (eutectoid temperature) where it
will all be the BCC, then it is cooled at different rates to different
temperatures to form the other structures. Another thing that changes is the
molecules that are formed such as the amount of Fe3C in steal. Different
combinations are given names such as pearlite, bainite, speroidite, and
martensite. Martensite gives you the best yield strength of all those and is
made by very rapid cooling. However, martensite has tension internally so it is
heated up again, but not as high as before to form tempered martensite. You can
also get a combination of martensite and the others by only cooling it to a
temperature to get a certain percent of martensite and then heated and cooled at
a different rate to form the other things.

There are a ton of possibilities of what can be done to get the properties that
you want for the application that you want to use it for. The overview above is
very brief and hopefully helps explain what it is a little better.

    ___________ =========================================== ___ /_/ / / / /
    Kevin Gilbertson - <a href="mailto:mail@gilby.com">mailto:mail@gilby.com</a> / _ '/ / / _'\_ / Unicycling
    T-shirts at <a href="http://www.gilby.com/">http://www.gilby.com/</a> \_ /_/_/,___/ / AIM/AOL:
    UnicyclingGilby /\/ /__________/ Unicycled Across Minnesota to help
    others! \__/ ================================================
7

Re: Hubs and Tires

In article <38324575.E327B4DC@tc.umn.edu>, Kevin Gilbertson
<gilb0179@tc.umn.edu> wrote:

>> Doesn’t heat treating makes steel both stronger and more brittle?
>
>In the sense that stronger means that it would take a larger load before
>failure, then that is correct.
>
>I’ll take a stab at trying to explain it (though I am not an expert about it):
>
>Heat treating steal will make the yield strength increase by about 3

snip at the risk of the pot, kettle, black syndrome, I am surpsised that Kevin
insists on calling it steal not steel!

– Rob.

… Rob Stone,
Dept Psychology, University of York, York, YO10 5DD, UK. tel:433161 See Anthony
Gatto perform at 13th British Juggling Convention.
13…16 April 2000 YORK, UK http://www.bjc2k.york.ac.uk/
…

8

Re: Hubs and Tires

> snip at the risk of the pot, kettle, black syndrome, I am surpsised that Kevin
> insists on calling it steal not steel!

Ahem! I’m sorry I don’t know what surpsised means, it’s not in any dictionaries
I looked in. Ok, so English isn’t my greatest subject.

                       -------------------------
                            Kevin Gilbertson
                        gilb0179@itlabs.umn.edu
                         <a href="http://www.gilby.com/">http://www.gilby.com/</a>