MUni Frames

My preferences:

-Flat crown if 24" or smaller- one foot skills
Otherwise a rounded crown for general XC riding 26", 29" or 36" MUni's-
I think they are less likely to catch on baggy shorts. The YUNi style
crown with sticky out bits has caught my shorts once or twice resulting
in a painful UPD.

-Weight: The lighter the better. If you're using DH wheel components,
on top of a heavy frame, the unicycle can end up weighing like a boat
anchor. The frame hardly ever fails, so is probably overbuilt for most
unicycles. I think a butted frame would be nice too- maybe thicker at
the ends for strength and thinner at the center.

-Low profile fork legs- maybe ovalised tubes so your feet don't rub as
much on the fork legs. I know someone who rubbed a hole in his 661 pads
from the fork legs.

-Titanium is my fav material; but Carbon fibre is sexy and you can make
it curve in all the right places.

-Hunter style frames look cool- but I think all that tubing adds extra
weight. Steve Howard frames look awesome too- lot's of holes but I
don't know how much they weigh.

-Brakes- I hardly ever use mine but they look good on a unicycle. Also,
a disc brake might be a good challenge for your project, because there
are few disc compatible Unicycles around- so lot's of potential to be
innovative.

-Split bearing holders are the way to go (as compared with lollipops).
Perhaps you could design a low-profile quick release system- that way
you can change the wheel size easily on the same unicycle.

-It would be good if the seat tube is able to take MTB standard
seatposts- usually 25.2mm (I think).

Keep us posted on developments!

Ken

--
GizmoDuck - NZUNI

o-kO

"Give man dead fish, and he feed himself for lunch, teach man to catch
fish, and he feed himself for life. Teach man to wheel ride, and he
make friends everywhere, anywhere, and even have lunch at their
place."
Old Chinese saying

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The Steve Howard frame I'm currently working on weighs under 2 lbs
(around 1.8lbs). It is made out of 3 chunks of aluminum and a piece fo
tubing. It rocks.

The Hunter style frames look cool and are really strong. I have plans to
build one out of titanium, but replace the 1/2" tubing with 5/8 or 3/4".
More on that a bit later in the post.

Steve Howard made a design of bearing holders that could potentially be
made into a quick release bearing holder. It has a piece of aluminum
that basically wraps around 3/4 of the bearing, with the fork leg making
the final 1/4 of the bearing. The piece of aluminum overlaps the fork
leg, where it could be skewered by a quick release clamp.

Titanium is an okay material for frame construction. It has an 8%
failure rating (or something like that), so if it breaks it won't become
a spear, instead it will bend. It's 2x as strong as steel with half the
weight. The only problem is that it's very difficult to machine and also
rather hard to weld correctly. Also, it flexes a lot, so larger
diameters of tubing than steel are neccessary. That's why my titanium
Hunter design has larger diameter tubing for the fork legs.

Carbonfiber is cool because it's stiff, light, and strong, but I don't
think it's durable to be a very good freeride muni frame. Maybe for XC
style with a 700c, but a hard crash on one's muni could possibly crack
the CF as could a hard crash during a sidehop.

Aluminum is about 1/3 the strength of steel with 1/3 the weight. That
means that with larger diameter thin walled tubing, aluminum frames can
be lgihter than steel ones. Steve Howard frames are also lighter than
most steel frames, too. Aluminum frames must be made stiff, because if
there is any major repetitive flex in the tubing the metal will fatigue
and fail. This means the both with bike and unicycle frames, the
aluminum must be VERY stiff. Some people like this, and like the weight
savings, but I've heard of people who absolutely hate their Wilders.

Steel is a very good material because it is extremely resistent to
fatigue, so you can crash on it, bend afork leg, and simply bend it
back. Mike Middleton Crashed his Hunter, anf bent the fork legs out of
alignment. He simply bent them back and it's just as good as before. You
couldn't dfo this with aluminum or carbonfiber. Steel is also extremely
strong and readily machined and welded. Not to mention it's dirt cheap
compared to almost everything else.

As for frame shape and design, I personally think that Hunter, Vortexes,
and KH muni frames look the best. I don't like the look of the Wilder,
and some don't like how it rides . Others love both it's looks and it's
feel. Ovalized tubing or rectangular tubing is pretty much a must unless
you do a Hunter design, which in effect is a giant tapered oval. KH
frames use ovalized steel tubing. From the perspective of someone who
uses their muni for trials while on the trail, I think that a
low-profile crown is a must. The Hunters and KHs and Wilders and DM
Vortexes have this, but not much else. The numbus crown sucks because it
bashes your knees and catches your shorts.

As for that titanium HUnter I have plans for, I'm basically going to
eventually make a Hunter frame out of titanium, but I plan to have 5/8"
tubing instead of 1/2" in the legs. It'll have a 28.2mm seatpost ID, and
be somewhere around 2 lbs in weight. I plan to skirt the process of
machining the titanium somewhat by making the brake bosses out of
aluminum which I clamp to the fork legs and also making the bearing
holders a-la Steve Howard so that I keep the machining of the titanium
to a minimum. Here's a link to a thread that talkd a bit more in detail
about the thoughts behind the design, including some info on the
materials: http://tinyurl.com/6dbsa

--
gerblefranklin - Trials Unicyclist

Don't you think it's a cruel irony that acting like a G.I. Joe in the
army can get you a Medal, while playing with one can get you thrown
out?

http://gallery.unicyclist.com/Trials-Muni

"Our enemies are innovative and resourceful. They will stop at nothing
to hurt us and our people, and nethier will we"-Dubya
Vote Kerry. Yeah, they both suck, but Kerry sucks less.
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I have an aluminium KH 20 prototype I got from Kris and though I weigh
210 lbs., it's totally burly and handles drops with ease. So aluminim,
for weight purposes, might be a consideration.

Carbon fiber is strong but probably not so good for bashing off rocks.
That's where steel is basically peerless. A titanium MUni would cost a
fortune, I think, though a T alloy might be affordable. I don't know
jack about it, only that titanium climbing gear is super costly.

There are axes out there now made of space aged plastics (polamers??) so
I suspect someone knowledgable in that field could serve up some
fantastic and lightweight options.

I think all the fancy designs are basically just cosmetics, but reducing
the profile might help so long as you can still run a Gaz.

Flat crown for one-footing and gliding.

JL

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rick_else said:

*i need to find info on the developement in the design of a certain
product. Naturally I have chosen to do mine on MUni frames. eg.
rounded or square crown, does weight matter, bearing casing type,
material, width, or anything else that you consider important for a
good MUni frame. Also, which frames do you all think look the best?
*

If you're interested in the development (history) of the design of the
muni frame, you should try searching archives of this forum. There is
some great info. Try searching on Telford, as one example. Then follow
things from there. It's great to look at current state of the art, but
also worth checking into the evolution of design that got it to where it
is today.

Which look the best? Well I'm a Hunter owner, Hunter fan. Also a Steve
Howard fan. If forced to choose on general coolness of appearance it
would be:
1) Hunter
2) Telford
3) SH scalloped Al frame
4) DM Vortex

Anything else you think important for a good muni frame?

Yes: double brake boss

--
tomblackwood - Registered Nurtz

Tailgate at your own risk.....

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wow, thanks everyone.

All those ideas are really great, and very helpful. I will make sure to
look into all of them.

I liked the idea of a quick release bearing casing, and that could be a
really good basis for my project. Has anyone tested the casings on steve
howards frame? Are they better than the standard ones?

Also, thanks for all your opinions on materials, there's lots of scope
for experimentation there.

I will keep you posted on any ideas i come up with.

--
rick_else - unofficial level 7 rider
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gerblefranklin said:

The Steve Howard frame I'm currently working on weighs under 2 lbs
(around 1.8lbs). It is made out of 3 chunks of aluminum and a piece fo
tubing. It rocks.

Those frames are very, very cool. Still, I grew up with the mantra
that tubes are by far the strongest shape for frame construction.

Reduced to its elements, the SH frame comprises two truss shaped legs
(carved from solid aluminum) bolted to a crown and seat tube. I
wonder if you could replace the legs with tubular trusses to save
weight. Of course, that would be a lot of welding!

Quoted message said:

aluminum [frmaes] must be VERY stiff. Some people
like this, and like the weight savings, but I've heard of people who
absolutely hate their Wilders.

I don't believe that fram flex is an issue for MUnis. That's not to
say the people you have "heard of" don't hate Wilders, but if they are
blaming it on stiffness I say they don't know what they are talking
about. This is because steel MUni frames are so stiff you won't feel
them flex in use, especially with fat cushoned seat between you and
the frame. More importantly, most of pedalling energy goes directly
into the wheel without involving the frame at all. A bicycle, in
contrast, has the pedals suspended by the frame inbetween the wheels,
and a fork that may flex significantly when braking.

Ken

I've tried a number of different frame designs and ideas. The CNC'ed
aluminum ones seem to be favorites and they've turned out to be a
reasonably good design. They are light weight, but have a tendency to
be flexy. You can see just about everything I've ever done here:

http://gallery.unicyclist.com/showard

The problem with a flexy frame is that the tire (especially a big one
like a 3.0 Gazz) can rub the side of the frame during steep climbs. I
think it's more that the frame twists rather than flex side to side.
This problem is even worse when using brakes since the brake pads need
to be pretty close to the rim. My current aluminum frame has brakes and
I've never had a problem with them rubbing but a 29'er frame I made had
enough flex that the brake pads rubbed. Some of my earlier MUni frames
were made with thinner fork legs (3/8" rather than the current 1/2"
thick) and they'll rub while climbing. I think the "ultimate" MUni
frame is the Wilder. Some people might not like them (I can't imagine
why not??) but I can't think of a lighter weight, stiffer design.

I think bearing holders generally leave a lot to be desired. I've tried
several designs but I'm not really very excited about any of them. The
last frame I made was a Coker and I just bored out shaft collars and
left a retaining lip on one side ... this works OK. The cleanest,
lightest design is the "pinch" type on my CNC'ed frames but they aren't
without their problems too. The "U" shaped bearing retainer on my
current MUni seems to work fine. I like it because there's no way to
overtighten it and put the bearing in a bind. It also retains the
bearing on both sides. However, I'm not really too excited about it -
I'm still looking for the ultimate bearing holder.

Here's what I like to see in a MUni frame design:

* Stiff enough the frame won't twist or bend to the point that the tire
or brakes rub.
* Uses a 27.2mm seat post.
* Light weight - around 2 pounds.
* Cool looking!

SH

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You may be able to use something like this for the bearing holders.

[image: http://www.mdc-vacuum.com/graphics/KF_Clamp.jpg]

http://www.hyvac.com/Products/Fittings/Clamps_fit.htm

These are clamps for vacuum fittings, but a bearing holder design could
be based on them.

--
Keith - unicyclist
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i really like the quick release bearing holders idea, it can be a real
pain tryin to change a tube mid-ride with all those little bolts to
lose, and worry about tightening correctly afterwards.

i can imagine it would be helpful in something like the red bull, where
you want to change your tube or fix a puncture in the minimum time
possible

I also think it has to look good, and be competitively priced, as even
if it has great features, most are still likely to go with a very cheap
nimbus 2, over the advantages of your frame.

--
manic_mark - level 4!

lever (dot) mark (at) ntlworld (dot) com
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I agree with Steve about flex, and know firstahand that you can feel
frame flex. I ride a 24" nimbus 2 (Yuni) frame on my muni, and on steep
climbs and descents I can both feel the frame flex and feel the little
knobbies on my tire hitting and rubbing the frame. It's a very noticable
effect. Also, anyone who's ever seat dragged or ridden an ultimate wheel
on any sort of incline will tell you that the frame plays a major part
in pedal power.

--
gerblefranklin - Trials Unicyclist

Don't you think it's a cruel irony that acting like a G.I. Joe in the
army can get you a Medal, while playing with one can get you thrown
out?

http://gallery.unicyclist.com/Trials-Muni

"Our enemies are innovative and resourceful. They will stop at nothing
to hurt us and our people, and nethier will we"-Dubya
Vote Kerry. Yeah, they both suck, but Kerry sucks less.
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Yeah I like the idea in QR bearing holders, would give a whole new
aspect on the project. I like Square shouldered and the main easy to
correct thing is tyre clearence...In the uk the nimbus 2 originals have
really small height clearence with a gazza creating a weapon..stones
spit out at speed! The new nimbus 2's have a good height but are far too
wide. Take note to this! Would make a nice muni frame between the two.
The other thing I prefer is a larger seatpost like 27.2 which makes
choosing a really nice bike seatpost/seatclamp a lot easier than 22.2. I
am really looking forward to seeing this frame when it's done and hope
it all goes well.
Thanks
Aaron

--
pluto - Muni obsesive

www.freeborn.co.uk

www.cumbriamuni.com

www.sixsixone.com

one or two wheels
+ a mountain
= fun
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