3 cross or 4 cross for 24" Muni/trials?

What kind of spoke pattern is better for MUni and trials for a 24"
wheel? I won't do drops over three feet.

Include an explanation of why in your answer if possible.

Thanks.


--
The Munieer - Mountaineer + Uni = MUnieer

Rod Wylie


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The tangential loading of spokes in a unicycle wheel is minmal when
compared to that of a cross country mountain bike, or any bike with a
disk brake system.

The effective moment experienced by the wheel is far less than what
would generally cause much detensioning of the spokes and therefore
whould cause little flex in the wheel.

A 4x will not support a radial load much better than a three cross,
since it is only the bottom few spokes that are losing some tension and
the rest of them along the top of the wheel are all making up for it.

Lateral laoding is affected only by hub width, and the ERD of the rim.
the triangle created here is the important aspect, therefore the spoke
pattern will have a negligible affect.

I'd go with a three cross as long as you are using at least a 36 hole
rim. I don't think you'll have any problems.

I have had to build four cross wheels in the past just because i
couldn't obtain the correct spoke length for a three cross.


--
SEMPER_UNI - Alethes Cycling, since 2004

Michael S. Pritchett
Alethes Cycling




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SEMPER_UNI om writes:

I'd go with a three cross as long as you are using at least a 36 hole
rim. I don't think you'll have any problems.

There are a couple of other considerations. First, there is the
reason for crossing spokes in the first place. Radial spokes (0
cross) pull straight out of the hub, putting stress on the weakest,
thinnest part of the hub. Spokes laced approximately tangent to the
hub place those stresses on much stronger parts of the flange.
Second, as SEMPER_UNI mentioned, there is some consideration of
wind-up when you pedal hard. Radial lacing allows much more rotation
of the hub for a given amount of wheel torque, which is alleged to
produce a "mushy" wheel.

Anyway, here's Sheldon Brown's advice about crossing:

The more spokes a wheel has, the higher the cross number for a
similar spoke angle. 48 spoke wheels are usually built cross 5,
40 spokes, cross 4; 36 spokes, cross 3 or 4; 32 spokes, cross 3;
28 or 24 spokes, cross 2...
[http://www.sheldonbrown.com/wheelbuild.html]

I think 3 cross is more common than 4 for a 36 spoke wheel. The only
disadvantage of 4 cross I can think of is a bit of extra weight
(n.b. my brain doesn't allow me to think of aero considerations in a
unicycle wheel).

Ken