I’m going to rebuild my wheel shortly with Monty 19" rim and Profile hub.
Do most of you guys do a 3x or 4x pattern with that, I know my old wheel that was stock from unicycle.com had a 3x patteren but I was planning on going with the 4x because its a bit stronger from what I’ve heard. Is that a correct assumption or should I get it built with the 3 cross patteren instead?
Mike
4X is good. It adds strength torsion-wise, which is helpful in trials. There is no problem with the angles associated with that combo; see these photos.
4x pattern is generally used with smaller sized wheels.
3x patterns are more common with your bigger wheels.
24" and under 4x for sure
26" not positive
28"and up 3x
the idea behind 4X on 26 inch wheels is that it makes the spokes more tangential. ideally you want the pairs of spokes to be parallel as they go toward the rim.
On a 19inch rim 3x is about as close as it gets.
I’m probably wrong but it strikes me that 4x in this situation just adds more complexity with no advantage and the possible disadvantage of having the spokes rub on the hub more as they move and bed in.
3x is deffinately the way to go. 3 is just as strong as 4 in this situation, and 3 is ever so slightly lighter, easier to build, and the spoke angles are better.
Also note: sem deluxes use 1 or 2 cross wheels.
i go with 4x every time i can.
even on my 48 spoked 700c utilitarian byke.
my old kh20 was 4x with no probs.
I don’t know what I’m talking about but I’ve heard that 4X is heavier and although it crosses more frequently (adding strength), the spokes are longer (apparently reducing strength).
Andrew
The 4 X is heavier but has greater lateral strength. 4 X also gives more flexi in the wheel vertically – to absorb shock. If you built a radially built wheel it would be very stiff vertically but perhaps fold like a potato chip the first time you did a side-hop. The larger diameter the wheel the more lateral strength is needed – if you are doing anything other than just riding
I build all my uni wheels 4 X because my personal preference is toward strength rather than weight – though I weigh 155 lbs… Also, I want there to be some flex in the rim
Tommy
4x is slightly heavier because the spokes are slightly longer. The difference for a trials wheel is miniscule. For example, for a Profile hub and Monty back wheel the difference is 9mm per spoke, or a total of 324mm, which is essentially two spokes-worth of weight.
It’s not really that they cross more frequently, Andrew, it’s that they come off the hub at an angle, which means they can exert force inline with the wheel rotation, which means that they can help strengthen the wheel during acceleration and deceleration in the forwards/backwards direction.
The length of the spoke doesn’t really have anything to do with the strength of the spoke; a spoke gains strength in its diameter and material.
[/B]Actually I don’t think the 4x has much to do with lateral strength; that is handled by the spoke tension and the brace angle (the width of the hub compared with the diameter of the wheel), coupled with the torsional rigidity of the rim. Except for imperfectly sideways sidehops, I don’t see that the spoking pattern has much to do with lateral strength.
The real weakness in a radial wheel is that the spokes, while rolling or accelerating, change length too much, thus fretting in the hub and eventually (quickly) breaking at that spot. Some road bicycles use radial spoking in the front wheel, where the static load is much less and there is essentially no torque being applied through the hub (rim brakes on radial wheels, not disk brakes!). Radial spoking in unicycles, where all the rider’s weight is on the wheel and large amounts of torque are being applied, was abandoned quite a while ago because of very fast spoke breakage.
It’s not quite true that the larger the wheel the more lateral strength is needed. It’s just that the wheel has to handle the load that you give it. If the wheel diameter grows, then the hub width has to grow with it so that the brace angle stays the same (all other things being equal). That way the wheel doesn’t get weaker as the diameter grows.
As far as flex in the rim goes, there is essentially none in a strong wheel, at least not in the way that you are thinking, Tommy. The real flex takes place in the spokes, and of course the most significant place of the tube/tire. In fact, the real job of the spokes is to keep the rim in its original shape.
A couple of good resources:
Jobst Brandt’s The Bicycle Wheel
Spoke Calculator by uni uk dot com
And a shameless plug! 
Thanks for clearing that up for me. One question, why is it important to have added strength while accelerating and decellerating on a unicycle? How would accelerating and decellerating do damage to the uni?
Thanks,
Andrew
U-Turn,
Thanks for the links! They are really great.
Tommy
Whenever you put a lot of force on a single pedal, you are applying a force to the surface on which the uni is resting, through the pedal, crank, hub, then spokes, rim and eventually the tire. For example, you do a stillstand on a slanted surface facing downhill. There is more force on the rear pedal to counter the forward push of the slanted surface, otherwise you would move downhill. This involves a torque, or twisting force on the hub which eventually puts the backward force on the tire that exactly counters the forward push.
On a radially-spoked wheel, there are no spokes that go that direction (they all go straight out from the hub); so the way the force is transmitted to the rim from the hub is by “winding up” the hub and spokes until the increased tension in the spokes matches the forward thrust. This involves a lot of spoke motion, both stretch and motion within the hub holes. The motion in the holes is called “fretting” and will lead quickly to spoke failure at the spot where the spoke abrades. On wheels spoked with a higher pattern, part of the spoke tension is in the direction of that twisting force so there is a lot less motion of the hub relative to the rim, and thus much less spoke motion in the hub holes.
On unicycles, there is always this kind of torque. Idling is constant acceleration/deceleration. For trials, this is especially so because you may be landing on a curved or narrow surface with a lot of forward and downward momentum to cancel. So you need a lot of strength in that direction because the torques will be high. These torques are much higher, I believe, than those involved with normal riding acceleration and deceleration.
On that front bicycle wheel for road riding with rim brakes, there is essentially no torque passed from the hub to the rim, so there is no need for the extra strength in that direction. Thus one can make the wheel lighter without compromise. For this wheel, the lateral forces are minor as well, so the rim can be lighter and there can be fewer spokes.
For a trials wheel, you just want it to be as strong as possible in all directions. When your technique gets really really good, think about lightening up your uni, but lighten the wheel last.
At Unatics we met a pro trials bicyclist who had a very light bike. He said he could have it that light because his technique was very good. A normal rider would simply break it.
One of the reasons we often use washers under the spoke heads of a uni is to support the spoke head better; this also helps reduce the fretting mentioned above.
These are just generalities but there isn’t much that I’ve found so far beyond Jobst Brandt’s reference. He doesn’t really treat lateral forces and rim stiffness that thoroughly because he is primarily concerned, I think, with road bikes. It’s a fascinating read, though.
Gerd Schraner’s book is very good too but is also focused on road bikes.
Hope that helps.
Sure thing. 
RE: Wheel building question
Wheelbuilder John Kovachi uses 4X for 20- and 24-inch wheels, 3X for 26-
and 28-inch wheels. The rationale: these combinations use
standard-length spokes, available in many bike stores. John has a
professional-grade spoke cutter/threader and can make custom spokes, but
his customers prefer standard sizes, for easy replacement when
necessary.
-John
-----Original Message-----
From: rsu-admin@unicycling.org [mailto:rsu-admin@unicycling.org] On
Behalf Of AccordNSX
Sent: Monday, March 31, 2003 1:48 PM
To: rsu@unicycling.org
Subject: Re: Wheel building question
4x pattern is generally used with smaller sized wheels.
3x patterns are more common with your bigger wheels.
24" and under 4x for sure
26" not positive
28"and up 3x
–
AccordNSX - Broken Neck
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Re: Wheel building question
On Mon, 31 Mar 2003 16:54:15 -0600, Max_Dingemans
<Max_Dingemans.l6gun@timelimit.unicyclist.com> wrote:
>Also note: sem deluxes use 1 or 2 cross wheels.
Yes my Sem 24" deluxe uses 1-cross. Early Semcycles (before there was
an XL) had radially spoked wheels. Semcycle have their philosophy on
this model focus on flexibility (in the physical sense), that’s what
they see as the advantage for the flexy frame as well.
My daughter’s Sem XL 20" uses 3-cross.
“I’m not tense, just terribly, terribly alert.”
Re: Re: Wheel building question
Yes apparently this lead to a lot of spoke breakage, so they shifted up.
Extra spokes add strength?
While we are talking about spokes, I was wondering about the number of spokes. I noticed that the Stealth Torker has 48 spokes, while the Kris Holm has fewer spokes (looks to be 36 or 30 from the picture). I always assumed that more spokes made the wheel stronger. So why does Kris Holm uni use fewer spokes? I assume that the KH has better quality spokes than the Torker, but I wonder if there is little extra to be gained by using extra spokes.
–Amos B.
Re: Extra spokes add strength?
The strong downhill rims that are used for muni are only available with 32 or 36 spoke holes. The downhill bike folks are not using 48 spoke wheels so downhill rims with 48 spokes are not available.
In general more spokes make for a stronger wheel. But the biggest factor in the strength of a wheel is the quality of the wheel build. A well built 36 spoke wheel will be stronger than a poorly built 48 spoke wheel.
Common spoke counts are 32, 36, or 48. The munis are using 36 spokes. Some freestyle and hockey unicycles use 48 spokes. 700c rims (used for 28" wheels and 29" wheels) are available with 48 spokes but 36 spokes would be more common.
an aditional note.
most tandem byke riders are now going with 40 spokes so the manufactuers of 48 holed rims is drying up fast.
i wish i could get a 48 spoked Profile hub for my Super 29er!
Re: Re: Extra spokes add strength?
not true
Halo rims and many others are available in 48 spoke patterns.
you could probably get profile to make you a 48º unicycle hub.