MUni Frames

Hello unicyclists

I have just started a product design assignment for college, in which 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.

I would like to know peoples opinions and preferences in their frames, and any suggested future improvements.

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?

Rick Else

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!


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:

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.


Re: MUni Frames

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

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.

Re: MUni Frames

“gerblefranklin” <> writes:

> 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!

> 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.


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:

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!


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

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

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.

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.

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.