Why do most wheels have 5 spokes?
 

I was the first one in to work yesterday and had to wait for someone with a key to show up. I noticed that 5 out of 6 vehicles had 5 spoke wheels and one car had 7. Since then I have noticed that most cars have 5 spokes, or as my wife's Expedition, 5 sets of two spokes. Most of the ones with more spokes were the sportier models. So is it just a styling thing? You would think that there would be the same number of spokes as lugs, but not necessarily.

So, other than the obvious "To keep the rim away from the hub!", does anyone have any idea as to why? Something to do with vibrations and harmonics would be my first guess.

Why do I even ponder such things anyway?:confused:

rbrowning i think this is a purely styling thing. 5 spokes looks better than 6 i guess.

The wheels will be balanced mechanically with either 5 or 6 or any number for that matter. So no issue with vibration or harmonics. A lower number of spokes say for an extreme example of 2 spokes would put significant stress on the spokes but from 4 or more spokes its not even a consideration.

Well worth pondering these sort of things its best way to find out something new

Perhaps styling enters in, but in earlier days an odd number of lug nuts seemed to have less effect or wheel warping and the associated vibrations. Still today odd number of attach points are often used where balance is critical. When it comes to heavy vehicles you may have notice six, eight, teh or more lugs. So as the number of attach points increases in number the load distribution is more evenly distributed and less critical. Today however it does seem that it has more to do with style as the previous poster mentioned.

If odd= better balance then the heavies would have 7, 9, etc. instead of 6, 8, etc., right? :confused:

First, there are probably 100 answers to this question and while some of them have a grain of truth to them, I'll bet that true answer is that there is no real reason.

- But -

Most vehicles have 5 lugs, so I supposed symmetry plays a role.

I've heard that using prime numbers has the effect of isolating vibrations. So 5, 7, or 9 are common used when the number of "X" is chosen.

^^ What he said about vibration plays a big role. I suppose it's also true that the engineering advantage of 5 spoke over 6 spoke is minuscule.

I looked around at wheels a few years back, and noticed a fair number of American cars with even numbers of spokes, but not nearly as many imports like that.

...anybody remember the THREE-spoke wheels from back in the mid-1970's?

...and SAAB used a 3-spoke rim as OEM for awhile on one model.

They're back, on Smarts ! ;)

How about the 3-lug Le Car?

It's just a styling thing.
The number of spokes has nothing to do with the number of bolts, though 5 spokes and 5 bolts create some symmetry.

BTW: I'm known for my profound dislike of 5-spoke rims :D

What's not to like about a lower-vibration (and therefore potentially incrementally lighter) design?

As long as there is some engineering sense behind a design, I can live with it.

I have a great dislike for 6, 8, and 10 spoke wheels.

The lightest OEM rims for my car, is a 7-spoke design - both in 15" and 16".
They're lighter than the 5-spoke designs.

I had an R5 was my second Renault and a good car. I put an oil pressure gauge on it and whilst going over some rough rr tracks it broke the fitting off somewhat seizing my engine I fixed the engine and drove it another year. Still getting 35 mpg without trying.

As far as 5 spokes I believe it to be the mark of the devil. The Pentagram you know.

...are you implying that CHRYSLER MOTORS™ is owned & operated by the Devil (wink,wink)?

http://www.allpar.com/images/logos/creed-pentastar.jpg

Well, it all depends.
Standing on two "feet" with a point up the symbology is positive.
Standing on a single point, there are negatige conotations:

http://vigilantcitizen.com/wp-conten...ifer_satan.gif

Higher aspirations vs. base instincts.

When a five spoke wheel is spinning, it's anyone's guess. :rolleyes:

Pentagon symbology

Pentagram

If the devil is in a rim he's going to get seriously dizzy ;)

Could be harmonic resonance. Rotary and radial engines (aircraft) almost universally have an odd number of cylinders. Could be for the same reason.

regards
Mech

Prius Rims
 

Prius rims (2004-2009) mostly came with the 6 spoke wheels, although they are a lot thicker than what I would consider "spokes".
http://upload.wikimedia.org/wikipedi...s2004DSide.JPG

Would a first generation Insight have three spoke rims?
http://static.howstuffworks.com/gif/...2101990002.jpg

I prefer to think of it as a spokeless wheel with three major and nine minor vents. Similarly, the Civic Hybrid wheels are a spokeless, five vent design:
http://www.technofile.com/images/hon...id_06wheel.jpg

I think an odd number of spokes is more appealing to the human eye.

I see 3-spoked alloys every so often, mostly on Mercedes. I believe they are not good for larger diameter wheels because the distance between spokes is big enough to allow denting/bending. I hate 4-spoke wheels, though.

Um, 9 isn't a prime number.

Hey, that's cheating!!

How about the 8-spoke DaVinci wheel?

http://ecomodder.com/forum/attachmen...1&d=1285059143

Prime numbers are desirable here because they have few divisors, and the ones they have are large. A 9-spoke wheel may have resonant vibrations at 1, 3, and 9 times wheelspeed, while a 6 spoke wheel may at 1, 2, 3, and 6 times wheelspeed.

Sometimes, resonant vibrations don't matter. e.g. if there's enough damping for the vibration to die out before the next excitation arrives, if excitations at that frequency are exceedingly unlikely, or if the frequency of vibration is too high for humans to perceive.

Robert,

I'm trying to understand this whole matter.

I have seen wheels with 3, 4, 5, 6, 7, 8,9, 10 and 11 spokes.

Beyond this it's too hard for me to count the spokes as they spin. :p

Presumably, all of these arrangements will run safely from 0 MPH, well up
beyond the highest legal Posted Speed Limit.

Since I haven't heard of any X numbered spoke wheel recall, can I presume
that whether through intentional design or blind luck, none of the issues you
have identified are likely to come up.

I tried to find an Internet site, blog, document, whatever discussing
wheel/spoke design, spoke cross section vs. number, etc.
Couldn't find anything.

Do you have any idea's for self-paced learning on this?

Rokeby,

All the wheels on the road are safe. Some are heavier than they need to be, and some transmit more NVH than they ought to. The number of spokes is a very minor point, but lacking small divisors in your symmetry is generally a good way to avoid resonant vibration at lower frequencies.

An even-numbered spoke count is a sign that designers and stylists came up with something, then told the engineers to make it work. An odd-numbered spoke count indicates the process went the other way around.

Further reading? Nah. The math behind NVH is boring, and since it's so far beyond the scope of the DIY'er, there's not much written on it.

...here's the DaVinci wheel I can relate to:

http://www.lifeisajoke.com/simpsons/...s-Da-Vinci.bmp

AFAIR, the only two wheels that were engineered rather than styled were the tension-spoked (bicycle) wheel, which was actually developed for the still unsuccessful aircraft of the mid-1800s. At higher loadings and smaller diameters, the spokes get thick enough to take compression loads, and the end fittings become useless weight.
In the 60s, the Minilite was designed as a superior alternative for sport and racing cars, with some actual calculations.
While unsprung weight is one of the biggest factors in ride and handling, the nature of wheels is almost unresponsive to fine-tuning of the structure. You need so much material for the hub and rim, almost anything can connect the two with reasonable success. These days, with FEA readily available, better wheels could probably be designed, but the performance increment would be easily overcome by BS and styling preferences. Cars are about image, not engineering goals. Nobody Needs fancy rims to drive around urban decay, but that is where you find them most often.

Any number that divides evenly into 360 is a easily usable number of spokes, as they can be spaced evenly around the circle.

Any number of spokes, even one, can be spaced evenly around a circle.

Just an observation on the question of "why do most wheels have 5 spokes?" Most vehicles also have 5 wheel lugs as well. One lug per spoke seems visually appealing.

I wonder what fuel economy advantage there would be in saying having
- 3 spoke light weight wheels that are easier for the engine to accelerate but have more openings hence cause more aero dag
- vs heavier disk wheels which are harder for the engine to accelerate but have less or no openings resulting in less aero drag

I guess he doesn't have to worry about the old broom stick in the spokes trick stopping him...


>

I believe that's why the two latest generations of Prius have had alloy wheels with plastic trims on the outer edge, improving aero while not adding too much weight (which is especially important on the outer edge as it has a greater effect).

Do a Google Images search for Minilite and see the only wheel worth having....

...now if I could afford a set.

You mean the Very Light Wheel?

http://farm5.static.flickr.com/4143/...9d4bf2ff_b.jpg

Is that the Continental tyre developed for the Loremo ?

That's a photo of the Very Light Car's wheel. I don't know the origin of the tires, but a quick Google search says I can buy them at Sears. They also fit a Smart, among other cars.

Hey Capri Racer, 9 is not a prime number!
BTW, to date I have seen wheels with 3,4,5,6,7,8,9,10,12,15 and 20 spokes. All except 7 have a geometric construction.

I have also seen them with 11 and 13 spokes.

pakamac -- Welcome to Ecomodder. First post in a zombie thread with a point that had already been made.

I know you can do better.

Bicycle Bob (in 2010) said the tension spoke wheel and the Mini-lite were the only ones 'engineered'. I'd suggest the Centerline Convo Pro. The corrugations reduce weight.

http://www.jegs.com/images/photos/10...-005143550.jpg
http://www.jegs.com/i/Center-Line-Wheels/184/005143550/10002/-1

That brings up a good question. I suppose if you angled the light weight ones enough so that it would lessen the drag and allow it to flow through without a problem you'd find your perfect solution!