[pugslybell]

hey i need to find the mathmatical formula for doingspokecalculations.doesanyone know it and if so do they know it in an excelor ti 89 friendly format. thanks in advance

 

[MisterMental]

spoke length =L
ERD = D
flange hole circle diameter [ c2c across hub flange] = d
flange width [thickness of hub flange] = W
flange hole diameter [diamter of hub flange spoke hole] = S
crossing pattern = X
number of spokes = N

work out first:
T = 360xX/(n/2)
A = (d/2) x sin(T)
B = D/2-((d/2)xcos(T))
C = W/2

Spoke length :
L = sqr(Asq+Bsq+Csq) - S/2

 

[pugslybell]

can i ignore flange width and flange hole diameter? by that i mean can i make this measurment once and call it good enough for all hubs?

 

[MisterMental]

no each hub is different
it would be the same for all hope bulb front hubs for example but not all hubs, all hubs in the same range will be the same eg all front XT disc hubs, all front Deore Disc hubs

 

[SwisSlesS]

There's a spoke calculator on the dtswiss website. There, you just choose your hubs, rims, spoke number, and lacing pattern and it tells you what size spokes to use. It's always worked for me.

 

[MisterMental]

yeah thats what ive always used, just that he asked for the formula so i gave it to him

 

[Matt D]

I don't know how friendly excel is with your program, but go HERE, save "spoccalc express", and copy the formulas into your program. MisterMental is right, the flange width is dependent on what hub you use, but spoke hole diameters are generally all the same (2.4).

 

[GeoffW]

try dtswiss website, I found it very helpful when I was figuring what kind of spokes to use

 

[Matt D]

Originally posted by GeoffW
try dtswiss website, I found it very helpful when I was figuring what kind of spokes to use

that's not what he's asking, he wants the actual formula for it.

But you are right in the sense that dtswiss has a nice calculator