I wonder if a spoked wheel can actually be stronger than a disc wheel. Suppose the spokes are properly designed-can the spoked wheel resist bending, as well as (or better than) a disc/solid wheel?
What other constraints are you imposing? I presume that the spokes can’t be thicker or of a different material than the equivalent portion of the solid wheel?
Without such constraint, we could be comparing flimsy solid wheels made of tin to huge, sturdy spoked ones made of cast iron - and it would be obvious that a spoked wheel could be stronger
Right-the constraints would be that the spokes would be of the same material and thikness, of the solid wheel.
The only scenario I can think of here would be if the material was of such properties that a solid wheel would be vulnerable to damage by its own weight, and might sag or buckle.
Otherwise, if the spoked wheel is just the solid one with pieces cut out, how can it be stronger? It might be more flexible (and thus less prone to failure), but that would be at the cost of far greater deformation, which doesn’t make it ‘strong’
The spokes on bike wheels are offset a bit, so they form a bit of a triangle. If you were to take a flat sheet of the same metal, with similar thickness, it would probably bend easier if you hit a curb or something.
I’m betting the solid wheel would support a hell of a lot more weight though.
I was wondering about that. Particularly from an aspect where the weight is increased like a very high speed rotation under the effect of centrifugal forces. You might be able to design a system where a full wheel causes failure at the hub, but the lessened weight of a spoke system might allow higher speed rotation.
Might not fit your definition of stronger however.
This is basically it. A spoked wheel has flex by design. So to a certain extent, and obviously we’re talking about light impacts, it’s more resilient than its solid counterpart. It will take a hit and rebound, as long as that hit wasn’t too significant to overwhelm the spokes, or too sharp to immediately bend the rim.
Stiffness is interesting too. Spoked wheels, in most non-wagon applications, have the spokes offset from the rim with two sets of spokes opposing each other on either side (left and right sides of the wheel). This increases stiffness dramatically over a simple inline arrangement.
I never studied bicycle wheel building to the depth I should have. I bet we’ve got a skilled wheel builder lurking around here somewhere…
A spoked wheel can be stronger, and is almost always stronger for a given weight.
The strength and stiffness of a spoked wheel come from preloading the tension in the spokes. It is difficult, if not impossible, to produce such preloading in a solid wheel.
For a rigorous analysis, see The Bicycle Wheel by Jobst Brandt
I always thought the bicycle wheel was the most brilliant demonstration of why reinventing wheels can be productive.
Spokes (like on a bike tire) hold the wheel with tension. The spokes are all pulling the wheel to the center, but because of the equal force, the wheel is balanced.
If you use spokes vs. an equal weight of a solid rim, the spokes would be stronger due to the tension on the wheel which is why bike wheels are spoked.
None tension spokes (such on a wagon wheel) might be stronger on a weight-by-weight basis than a solid wheel because the spokes are cylinder in shape and thus thicker and stronger than what a solid rim wheel would be.
If you take a disk and cut out pieces, the solid shape would be stronger, but spokes are not a mere cutout of the wheel. They use either tension or cylinder shapes to help support the wheel and can be stronger than a solid rim of the same weight.
The trick to understanding spokes - they are not holding the rim out from the center, they are pulling it in. (unless we’re talking old wagon wheels, which are holding it out) - but with bike rims the spokes are pulling to center.
Correct. One way to say it is that the hub is hanging from the spokes that come from the top of the rim, not resting on the spokes going to the bottom of the rim. The reverse on true on wagon wheels.
You mean a…spokesman?
Understood, but such spoked wheels are no longer easy to compare to solid ones (which was what I was on about at the top of the thread).
The sort of spoked wheels I think we could directly compare to solid ones might look like this:
http://www.wicketts4wheels.com/Autopart%20Wheels/4x4/02%20-%20Legend_5_HS_600x600.jpg
Or this:
Material matters
A disc of wood is stronger in the direction of the grain than it is across the grain, and if it is cut as end grain faces, it would be more vulnerable to pressure in and out along the axis.
Spokes can be made of the same type of wood, and the grain of each aligned raidialy, and the rim of segments coopered properly, and the wood will have the greatest strength at each point for the direction from which stress is likely to be applied.
Tris
This old thread, about the relative strengths of hollow versus solid cylinders, has a lot of information of relevance to the OP.