mrblue

I am thinking about building a set of wheels using the DT Swiss 350 straight-pull hubs. I went online to use the spoke length calculator at the United Bicycle Institute website. Then I started thinking...will this give an accurate length for straight-pull spokes?

Can anyone give me some insight on how to calculate spoke length for straight-pull spokes? Or do the online calculators work just fine?

Thanks.

rhenning

If you tell the program you are doing 0 cross wheels it will give you the correct answer providing all the other informatiion is also correct. Roger

tomacropod

Straight pull and radial are different things. Straight pull is just a type of spoke head.

My suggestion would be to avoid straight pull spokes.

- Joel

FBinNY 

Straight pull calculations depend on the specific construction of the hub. You have to do a bit of mental gymnastics to convert normal J-bend calcualtions to straight pull. Here's an example.

Consider a hub with a "star" pattern "flange" like this one.



If you were using J-bend spokes they would be entering the hub through equally spaced holes drilled sideways through a circle the same diameter as the existing spoke holes. So cross count, and CTF distance are as per normal, but each spoke but you have to add (or subtract) the distance from the theoretical spoke hole to where the head actually sits.

For reference, J-bend spokes are measured to the inside of the bend. Likewise straight pull spokes are measured to the inside (bottom) of the head.

The first time I did this, I ended up making up a paper template and holding it against the hub so I had a reference, and it made the job easy. Now I don't bother, and can eyeball the adjustment pretty accurately.