Source
r/science•
semanticprecision

Why do car wheels have an odd number of spokes?

My morning commute has been taking a little longer than usual, and I've been using some spare moments to -- and mind you this is a little embarrassing -- count the "spokes" on car wheels (not sure if they're "spokes" on a car, but they are on a bike, so I'll stick with it). So far, I've seen counts of 5, 7, 9, and 11; generalizing, I'll assume that most-if-not-all vehicle wheels contain an odd number of spokes.

Does anyone know why this is? I'm not up enough on my physics to put together a cogent explanation that way. Or is it purely stylistic?

Posted Jan 28, 2010, 1:05 AM UTC

39
pythor•

WAG, here, but I would say that an even number of spokes gives the weight of the car a straight path to the ground, so that shocks are transmitted directly through the spokes, causing extra stress. With an odd number of spokes means that there is always at least one end of the wheel that has the stress spread across two different spokes.

2
benclayton•

I think this is the best answer, and for those of you seeing 4 and 6 spoke wheels, are they hub-caps, or actual rims?

I also think that an odd number seems a bit more aesthetically pleasing.

1
ghidra•

I've had 6 spoke wheels. Also seen 4 spoked wheels too. I think you just had a day of seeing only odd numbered spokes. I don't think anyone makes a 2 spoke wheel, or a 1 spoke wheel for that matter.

1
Lyrad1000•

or a 0-spoke.

1
dryguy•

Not so.

http://spluch.blogspot.com/2006/10/hubless-wheels.html

http://www.doobybrain.com/2009/06/17/lexcarbon-monospoke-bicycle-wheel/

3
lyingit•

I've seen four "spoke" wheels before, but usually those are hub capped, near solid wheels.

my assumption would be it's a style thing to match the lugnuts, most cars have 5 lugnuts (minimum) so that you wheel doesn't wobble, when you tighten them you go in a star pattern too.

I can't imagine it gives much more function, as there are 3 spoked wheels too, although the most secure chair/tables are three-legged

1
[deleted]•

I was once told that - in regards to bicycle rims, specifically - the number of spokes has to do with the probability of the entire wheels structure failing when one spoke fails and the exact number of spokes used depends on the size of the rim.

1
losewinspin•

Purely aesthetic. Notice that all of the patents for wheels and moulded wheel covers are design patents (ie, aesthetic). Example

1
permaculture•

10 spoke rims

1