Hi there,
I was wondering if anybody any experience in making their own unicycles, out of
mostly standard off the shelf bike parts.
If so how did you get around the obvious difficulties - the crank area - and
from then onwards how to bolt the frame to it.
I’m asking because I fancy an MUni, but really the market is quite small…
cheers
Re: Making a Unicycle
At 03:26 AM 11/22/97 GMT, Bruce Bundy wrote:
>willing to build up and mail more of these dream machines (~$700 COD) (408)
>662-7003 but it’s definitely fun to put together yourself. Good Luck!
Hey, sounds very interesting! I definitely would like to see one up close, and
will start saving my lunch money as of today . . .
I’m pretty tired of riding my cobbled-together “piece of Schwinn”!
John Foss, the Uni-Cyclone unifoss@calweb.com http://www.calweb.com/~unifoss/
“Never two tired”
Re: Making a Unicycle
I have been considering making a MUNI for about 6 months and have some questions
and ideas to bounce off the experts since I personally lack the exposure and
experiences many of the readers of this news group have.
I have 3 major areas of concern; axles, bearing holders, and the frame.
Axles: After reading the news group posts and web pages, it seems the axles are
a weak point for many munis today. I think strong axles could be made from high
strength steels or titanium. Does anyone know what specific material suppliers
use to make commonly available axles? Are most axles a standard size? (length
and diameter) How does the axle interface with the hub? (if they are typically
welded together, then dissimilar materials will propose a problem) I thought I
would have a machinist make 5-10 axles from a high strength material and sell
them for cost to spread the expense over a few parts. Any recommendations on a
material or an alloy would be welcome. On the other hand, I understand the
Semcycle axles are very strong. Maybe there is no need to go through the hassle
of making axles…
Bearing holders: I found myself in an redundant design loop when I considered
the frame and bearing holders and determined I need more information. I have
exposure with two different types of bearing holders. My first unicycle was a
Zefer and it has a holder made from an aluminum casting. The bearing is pressed
into the casting. The casting is attached to the frame by sliding it inside the
tube of the fork and is secured by two bolts, as shown below.
___
| O |
| | <== This part slips into the fork
| O | and the holes are tapped for the bolts.
| |
/
/ ___
| / \ | _/ | The casting is shaped some what like this
\ / and has the bearing pressed inside. ____ /
I think I read someones description of a Pashley Munis bearing holder and it
sounded similar to the one shown above.
My other unicycles are Semcycle XLs. Their holder is a two piece hat shaped
clamp. One half is welded to the frame and the other half captures the bearing
and is fastened to the other half with small bolts, as shown below.
| | <== bottom of frame
__|__|_ / \ __T__/ \__T__ __|__ __|__ T \ / T Two clamps with
bearing \_______/ held inside.
Of the two designs, I like this one the best. I would like to know how Miyata,
the other Semcycle, Schwinn, etc. make their bearing holders.
Frame: I have considered buying a mountain bike tire for my Semcycle XL and
there was not enough space between the forks. I read that this is an issue with
other standard unis available today. So we should consider making a custom frame
for a muni.
I am sure many people have looked at mountain bike forks and thought it would be
a good start for a unicycle frame. Mountain bike frames use a variety of high
strength materials. The have relatively high production volumes which keep
prices reasonable. They also are the prefect size for a mountain bikes tire.
[thats obvious I suppose 
] [this section is focused on frames, however I am
leaning towards a 26 inch wheel for a muni with approximately 6 inch cranks]
When one considers a mountain bike fork, you must consider suspension. I have no
clue if a suspension is a desirable feature on a muni, however it would be neat.
Cannondale has a fork with a suspension in the head set instead of the blades of
the fork. (see pictures of them at www.cannondale.com or more directly at
www.headshok.com/html/products.html) Check out the DD60, MC60 and the
DD25.
OK, the down side to a bike fork: The part of the fork where the bike axle
attaches would have to be removed and replace with a bearing holder. The
spacing between the fork would have to match that of the axle and hub, and the
cranks would have to have plenty of clearance. Then the seat post must attach
to the fork and with the fancy Cannondale fork, this would be tricky (although
not impossible)
Well, buying a bicycle fork and modifying it may be a waste of time and money.
Especially if the suspension is a undesirable feature. So I began thinking about
making a frame from scratch. I have had lots of ideas but my lack of exposure to
bearing holders is a major stumbling block. Is a light weight frame an issue
with these unicycles? (As a very proud owner of a Tom Miller giraffe, weight is
NO concern!) I think one could make some nice muni frames in aluminum with tubes
and extrusion. (I know an extrusion die costs in the neighborhood of $1000, but
I am a dreamer)
I have been further inspired by Bruce Bundys recent post. I like his design
because he uses proven, available parts (axle, hub, bearing holder etc.) and
makes a custom frame. His offer to sell one for ~$700 is interesting, however as
he says, …its definitely fun to put [one] together yourself.
Thanks in advance for your responses!
Greg Caster Lexington Kentucky
Re: Making a Unicycle
At 09:25 PM 11/26/97 -0800, Greg and Alexandra wrote:
>I have been considering making a MUNI for about 6 months and have some
>questions and ideas to bounce off the experts since I personally lack the
>exposure and experiences many of the readers of this news group have.
>understand the Semcycle axles are very strong. Maybe there is no need to go
>through the hassle of making axles…
Semcycle and Miyata have fine axles, but neither holds up to any extended amount
of MUni riding. The kind of torque that gets applied when you ride on steep
stuff, and the longer crank arms we use both put the axle under a great deal
more stress than it gets on a regular unicycle. Any really good MUni will be
built starting from the axle and working outward.
In other words, I think this is the order of importance:
If you want a serious MUni for serious rough terrain riding, make a strong axle.
George Peck has had some killer axles made for him over the years. These days
he’s using 3/4 inch titanium, I believe. Contact him at <gpeck@arctic.net>
As for forks, the nicest ride on a MUni I ever had was on one with a Rock Shox
fork. It was built by Daniel Hopkins Daniel <DJHfilm@aol.com>, who lives in
Tenessee. Maybe not too far for you to meet? I hope these guys don’t mind me
sharing their email addresses.
Do your research, and make something great! Maybe I’ll buy one as well . . .
John Foss, the Uni-Cyclone unifoss@calweb.com http://www.calweb.com/~unifoss/
“Never two tired”
Re: Making a Unicycle
Simon, and other potential unicycle makers,
I am now riding a custom MUni, which is a combination of off-the-shelf and
homebrew bits and pieces. All of the stock frames that I have seen have some
kind of clearance problem with either larger wheels (26" or 700c which works out
to about a 28" rolling diameter with a fat tire) or cranks, which can tend to
rub the frames when tightened down sufficiently to stay put. Also they tend to
be simply stamped steel, heavy, and too flexible. I am using a custom tubular
lightweight chrome moly frame designed and built by Rick Hunter of Rock Lobster
cycles in Santa Cruz, California
(408) 469-6748. This comes complete with excellent bearing holders designed for
the Semcycle deluxe axle, which comes with bearings and can be ordered
from Sem in Livonia, Michigan (313) 421-2505. This is a strong,
heat-treated chrome moly axle which comes welded to hub flanges ready to
build a wheel. Make sure you get spacers with the bearings and put them on
first, as it will require a hefty bearing puller to get them back off, and
without them the bearings will press directly against the hub flanges and
there will be no frame clearance. I am using a 700c Mavic rim with DT
stainless spokes and 170mm Deore XT cranks. It’s VERY important to use a
right-threaded left crank on the right side or your right pedal will keep
falling off. If you have trouble finding that (try a tandem bike
manufacturer) you can helicoil a standard left crank. Everyone is bound to
develop their own tastes, but I believe that 170 cranks with 700c wheel is
ideal for mountain unicycling. Miyata and Viscount make good seats, and
seats and seatposts are available from the Unicycle factory (Tom Miller)
(765) 452-2692 in Kokomo, Indiana. I am willing to build up and mail more
of these dream machines (~$700 COD) (408) 662-7003 but it’s definitely fun
to put together yourself. Good Luck!
Bruce Bundy
Re: Making a Unicycle
Greg and Alexandra wrote:
>
> I have been considering making a MUNI for about 6 months and have some
> questions and ideas to bounce off the experts since I personally lack the
> exposure and experiences many of the readers of this news group have.
> I have 3 major areas of concern; axles, bearing holders, and the frame.
interesting that you do not consider the seat a concern aswell, When
manufacturing my own uni’s the seat has often been difficult to manufacture
or purchase.
> Axles: After reading the news group posts and web pages, it seems the axles
> are a weak point for many munis today. I think strong axles could be made from
> high strength steels or titanium. Does anyone know what specific material
> suppliers use to make commonly available axles? Are most axles a standard
> size? (length and diameter) How does the axle interface with the hub? (if they
> are typically welded together, then dissimilar materials will propose a
> problem) I thought I would have a machinist make 5-10 axles from a high
> strength material and sell them for cost to spread the expense over a few
> parts. Any recommendations on a material or an alloy would be welcome. On the
> other hand, I understand the Semcycle axles are very strong. Maybe there is no
> need to go through the hassle of making axles…
The long and short of it is that the hardest steels available have been used and
have failed as unicycle axles. That is not to say that a hub machined from a
decent billotted steel with purticular attention payed to the machining around
the 5/8" square taper, i.e. no sharp edges and generious radi where ever
possible, then hardened…, will not last the life of the unicycle. Go for
it! What would be better, would be to look at the top end BMX hubs as they
experience the same if not higher forces than unicycles. They use up to 1"
diameter round bar (or bigger and hollow) with a broached or rolled spline. They
then use a different design for the crank, a broached tube with one or two pinch
bolt to the rear. In general terms this is the direction I think you should be
looking in. There is only a few problems I can see at the outset:
a: You need to manufacture the cranks as well as the BMX ones are
definately too long.
b: The standard design used on BMX’s have the pinch bolts at the opposite end to
the pedals. This would be bad for crank idling. I think the pinch bolts could
be on the same side as the pedals (but I have not layed it yet).
c: The bearing need to be bigger, you can get 42mm od bearing with a 25mm id,
they are not common, but the load area higher than those on the
40mm/17mm ones used on the better unicycles - so you cannot retro fit this type
of hub to a standard unicycle.
d: One advantage that is worth mentioning is that the cranks could be fitted at
different widths depending on the riders preference. I am seriously looking
at manufacturing some like this, I have the machinist, one of the best welder
in this region and even a company who can do the broaching. I just need the
time to get it sorted!
> Bearing holders: I found myself in an redundant design loop when I considered
> the frame and bearing holders and determined I need more information. I have
> exposure with two different types of bearing holders. My first unicycle was a
> Zefer and it has a holder made from an aluminum casting. The bearing is
> pressed into the casting. The casting is attached to the frame by sliding it
> inside the tube of the fork and is secured by two bolts, as shown below.
> ___
> | O |
> | | <== This part slips into the fork
> | O | and the holes are tapped for the bolts.
> | |
[i]> / [/i]
[i]> / ___ [/i]
> | / \ | ___/ | The casting is shaped some what like this
> \ / and has the bearing pressed inside. ______ /
>
> I think I read someones description of a Pashley Munis bearing holder and it
> sounded similar to the one shown above.
>
> My other unicycles are Semcycle XLs. Their holder is a two piece hat shaped
> clamp. One half is welded to the frame and the other half captures the bearing
> and is fastened to the other half with small bolts, as shown below.
>
> | | <== bottom of frame
> ||_ / \ T/ _T_ | | T \ / T Two clamps with
> bearing _______/ held inside.
>
> Of the two designs, I like this one the best. I would like to know how Miyata,
> the other Semcycle, Schwinn, etc. make their bearing holders.
I agree with your conclusions, I would add that there is a difference between
the clamp designs available. The pressed steel ones are of a conciderably lower
quality than the ones that are machined (look at DM’s Unihock for an example of
good design). If the bearings are not held correctly they tend to fail. Another
point worth noting is that if bolts are used to secure the bearing holder in,
then they should be from front to back not side to side as they can catch your
ankle when riding.
> Frame: I have considered buying a mountain bike tire for my Semcycle XL and
> there was not enough space between the forks. I read that this is an issue
> with other standard unis available today. So we should consider making a
> custom frame for a muni.
>
> I am sure many people have looked at mountain bike forks and thought it would
> be a good start for a unicycle frame. Mountain bike frames use a variety of
> high strength materials. The have relatively high production volumes which
> keep prices reasonable. They also are the prefect size for a mountain bikes
> tire. [thats obvious I suppose ] [this section is focused on frames,
> however I am leaning towards a 26 inch wheel for a muni with approximately 6
> inch cranks] When one considers a mountain bike fork, you must consider
> suspension. I have no clue if a suspension is a desirable feature on a muni,
> however it would be neat. Cannondale has a fork with a suspension in the head
> set instead of the blades of the fork. (see pictures of them at
> www.cannondale.com or more directly at www.headshok.com/html/products.html)
> Check out the DD60, MC60 and the
> DD25.
>
> OK, the down side to a bike fork: The part of the fork where the bike axle
> attaches would have to be removed and replace with a bearing holder. The
> spacing between the fork would have to match that of the axle and hub, and
> the cranks would have to have plenty of clearance. Then the seat post must
> attach to the fork and with the fancy Cannondale fork, this would be tricky
> (although not impossible)
If you are interested in suspention then don’t use the Cannondale one as it has
an adjuster on the top. Look at the one on the Action-Tec bikes, it is a lot
better and it is the one that Cannondale copied. It uses an oil damped, duel
spring suspention into a single shaft, with CrMo forks. It is manufactured in
Silverardo in South California by Russ who is a very skilled designer/machinist
and I am sure would talk to you if you would like to go down this avenue.
Warning though, you need to be tall to ride one, I cannot as I only have an
inseam of 30".
> Well, buying a bicycle fork and modifying it may be a waste of time and money.
> Especially if the suspension is a undesirable feature. So I began thinking
> about making a frame from scratch. I have had lots of ideas but my lack of
> exposure to bearing holders is a major stumbling block. Is a light weight
> frame an issue with these unicycles? (As a very proud owner of a Tom Miller
> giraffe, weight is NO concern!) I think one could make some nice muni frames
> in aluminum with tubes and extrusion. (I know an extrusion die costs in the
> neighborhood of $1000, but I am a dreamer)
Weight (and ridgidilty) is a big issue in my books as it effects the properties
of the riding, the lighter the uni the easier it is to use. I have a 7lb
mountain uni and it does perform rather nicely. I am on a mission at the moment
to manufacture a 6’ giraffe that weighs only 11 lbs, my problem at the moment is
getting a 150mm aluminium crank set with a single small chain ring (38 tooth
would be great). Anyone have any ideas? One thing I have learnt from the early
CF uni’s is that the crown width of Mountain bikes is too big and catches on
your knees (it doesn’t bother me luckly). I reduced the size on the Mk4’s by
10mm and I still get comments that they are too big. I am about to layout for an
investmant casting tool for the crowns for the Mk5 CF uni which will be smaller
again by 10mm and bonded instead of clamped. My dream at the moment is to
manufacture some CF uni’s with ovel tubing, but I don’t know anyone with an ovel
mandrel. oh well…
Good luck
Roger
-----------------------------------------
Roger.Davies@Octacon.co.uk
Stockton
North East England
Re: Making a Unicycle
On Thu, 27 Nov 1997 22:42:11 +0000, Roger Davies
<Roger.Davies@octacon.co.uk> wrote:
>I am on a mission at the moment to manufacture a 6’ giraffe that weighs only 11
>lbs, my problem at the moment is getting a 150mm aluminium crank set with a
>single small chain ring (38 tooth would be great). Anyone have any ideas?
I was about to suggest the cranks I’ve used, but then checked - 170s I’ve got a
17 tooth chain ring fitted to it currently, do you remember the failure I took
to Gloucester?
My problems with the bottom sprocket have been fixed. I’ve got a bit of flexing
to take out out of the frame, I’ve found where is occurring, but I’ve not done
anything with it yet. I’ll try to get my finger out & get it finished & painted
for York - it’s a bit heavy tho’.
Regards Colin.
3rd York Chock Fe(a)st 24th Jan 1998 http://www.york.ac.uk/~rfs1/yjf/