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Je to zkopirovane z knihy Roger musson, Professional guide to wheelbuilding.

Straight pull spoke lengths

Straight pull hubs that require straight pull spokes need a different approach to calculating spoke lengths. I am talking here about standard straight pull spokes, the ones where the spoke head looks like those shown on page 22. You cannot use a spoke length calculator for this type of hub because there are so mainy variations on the design of straight pull hubs. The DT-Swiss spoke calculator includes an option for straight pull hubs but it requires dimensional data that is ambiguous meaning it's not possible to measure it yourself or reliably obtain it from the hub manufacturers, although DT supply data for their own hubs.

If you have a wheel using a straight pull hub and the rim has worn out and you'd like to replace it with a different rim you need to use the procedure described above for „Spoke lengths for a different rim“. Before you do anything with straight pull hubs, either buying the hubs or attempting to calculate spoke lengths make sure you can purchase straight pull spokes because they are ve1y difficult to find.

Spoke lengths for a different rim

Once you have built a wheel and later decide to build another using the same hub, same spoke count and same lacing pattern but this time using a different rim then calculating spoke lengths is very easy. All you do is compare the rim diameters and modify the spoke lengths you previously used. Here is an example:

I have already built a wheel that required 262mm spokes. With the next wheel eve1ything is the same except for a different rim. The previous rim had an ERD of 540mm and the ERD for the new rim is 544mm so the spokes need to be 2mm longer and I will use 264mm. All I did was use half the difference in rim diameters to modify my existing spoke lengths. If my new rim was smaller in diameter I would be subtracting rather than adding. I use this method all the time since I tend to build the same hub onto lots of rims and it provides fast and ve1y accurate spoke lengths. You must have a record of the previous wheel, you need the rim ERD and the exact spoke lengths for it, and all this information is in the notes you made whilst building the previous wheel.

If you are replacing a rim and the two ERD's are different and you wanted to reuse the old spokes then read the section on rim replacement on page 107 because there's still a chance the old spoke lengths will be suitable. If you have the same hub but with a different spoke count or require a different lacing pattern then use the online spoke length calculator. Once you determined the exact spoke lengths for this new configuration they become your standard and for other rims just compare rim diameters as before.

Straight pull spokes

Hubs must be specifically designed to take straight pull spokes and although a few of them exist they are likely to be problematic in calculating spoke lengths and finding a supplier of spokes. ·wheels built with straight pull spokes are no better (or worse) than those using normal hubs and spokes. There is nothing special in the manufacturing process of straight pull spokes, in fact they are easier to make because they just take them off the spoke making machine one stage early before they receive the thump that bend over the elbow.