spoke calculation formula?

Unicycles and Equipment
1

is there a formula to calculate the length spokes need to be?

2

Uni.com in the uk has a spoke length calculator. You select the hub, rim and number of crosses and it tells you the length.

3

You can find many with a quick google search. Here’s one: http://users.senet.com.au/~mitchell/misc/html/spoke.htm

4

but i want to be able to get a hub and rim and find out what length i need instead of searching around, emailing and caLLing, only to find out that no companys have my parts in the calculator

5

hey thanks

one more question, when building a wheel, how do you determin the number of cross when lacing the spokes?

for example, say im bulding a four cross wheel, as im lacing it, how do i space the spokes on the hub/rim so it will be 4 cross when im done

thanks
jesse

6

if the numbers aren’t in the calculator, you’re going to have to do some work. if you just shoot out a question and don’t even bother telling us what kind of rim or hub you’re using, you’re never going to get any information without looking for it yourself.

check out sheldon brown’s “spocalc”… an Excel-based spoke length calculator. instructions for measuring your hub / rim are on the site. you may be able to obtain some measurements by contacting the manufacturer of your gear, or an authorized retailer.

P.S. I found the above link, as well as a couple databases of measurements, with ONE GOOGLE SEARCH… it took less time to make the search than it would to start a new thread. what’s so hard about searching for yourself? you might learn something in the process… that’s not a bad thing, y’know…

Edit: see http://www.sheldonbrown.com/wheelbuild.html to learn about wheel building. it covers cross patterns and everything else you’ll need to know.

7

k sorry

8

Re: spoke calculation formula?

On Thu, 22 Jun 2006, unijesse <> wrote:
>
> one more question, when building a wheel, how do you determin the
> number of cross when lacing the spokes?

Install all of the trailing spokes first, with heads on the outer face
of the hub. Then, when you thread the first other spoke in, you
simply weave it in applying the number of crosses needed.

Read this: http://sheldonbrown.com/wheelbuild.html
or buy the book ‘The Bicycle Wheel’ by Jobst Brandt.

Don’t forget to stress-relieve the spokes when you’ve built it, but I
personally don’t like the method recommended by Sheldon - I do the
‘grip pairs of spokes’ method followed by side-loading the wheel.
Put a block on the floor, place the end of the axle on the block so
the rim is parallel to the floor, then lean down on two opositte
points on the rim. Rotate the wheel slightly and lean down again.
Repeat 'till you’ve been right round the rim. Turn the wheel over and
repeat. Repeat from the start until there are no more pings.

regards, Ian SMith

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9

Re: spoke calculation formula?

On 23 Jun 2006 12:17:20 GMT, Ian Smith wrote:

>Put a block on the floor

Ian, you could use your helmet for that (if you had one, that is).

Klaas Bil - Newsgroup Addict

“I’m slowly but surely stealing Wales and bringing it back to my house on the wheel, frame and cranks of my muni. - phil”

10

Here is the link:
http://www.unicycle.uk.com/SpokeCalc.asp?id=269

it is set up for building unicycle wheels so ignores the dishing required for bike wheels. There are also all the unicycle hubs added in to make it easier for you.

Roger

11

When determining how many crosses you are going to have you need to take into consideration the wheel size. When I built my trials wheel I was planning on doing a 4 cross as then I could use longer spokes. I went to the bike shop to buy the spokes and explained what I was doing and they advised me against that.

The reason is that on such a small wheel when the spokes are crossed like that then the spokes begin to overlap onto the buts. This means that you have a stress point right ontop of another stress point and will cause you to snap spokes like crazy. So basically you want to keep with three cross at most up until at least a 24 inch wheel. I would probably only use four cross on a 29 inch wheel and even then I probably wouldn’t do it because it would be adding alot more weight to an already heavy wheel.

Hope that helps.