single butted spokes

17:21 Mar 13, 2019 

Single Butted Spokes:
These spokes can be identified by a single change in diameter between the neck and the body of the spoke. The neck is slightly thicker than the body to improve durability for disc brake and other heavy-duty applications. Single butted spokes are slightly heavier than double butted, but are also slightly less expensive. Single and double butted spokes are used for similar applications. Single butted spokes with 2.3mm neck diameters are also useful for wheels to be rebuilt with used hubs that have worn mounting holes in the flanges.
http://www.wheelbuilder.com/pages.php?pageid=16

19:05 Mar 9, 2019 

Double Butted Spokes
Lighter than Straight Spokes
More elasticity in the wheel (less rigid / will flex some before breaking)
Spokes will bow out less at the crossings
Easier to bend/lace
When overtightened or stressed too hard, the spoke is more likely to snap than the rim eyelets or the hub's flange

17:48 Mar 9, 2019 

6


In his book 'The bicycle wheel' Jobst Brandt, says that double butted spokes will be more resistant to fatigue failure when built into a wheel.
This is because spokes break because of the cyclic stress they suffer as the wheel rotates.
As the spoke rotates thru the bottom of the wheel it experiences a reduction in tension.
Butted spokes are more elastic so this reduction in tension is spread over more spokes, each experiencing a smaller reduction in tension.
Wheels are an order of magnitude stiffer than the tyres they roll on, so any stiffness differences will not be noticeable. A wheel built with butted spokes will be able to carry a heavier load before any of the spokes become slack. At this point the rim is no longer restrained and the wheel will be more likely to collapse.