Construction of the spoke.

Construction of the bicycle spoke.

constructie van de spaken
The bicycle spokes are inserted through a hole in the hub, and fixed with the aid of a spoke nipple to the rim.
With the nipple the spoke can be brought at the correct pre-tension, and the rim can be perfectly centered and focused.
The bicycle spoke nipple is secured by the bias against vibration loosening.
As soon as the tension disappears the nipple can vibrate loose, so that the tension in the spokes is no longer equal, and there will be a stroke in the wheel.
A high tension flocks the spoke nipples better. The nipples can also be secured with a liquid sealant.

The ordinary spoke consists of a steel wire with at one end a thickened head bent in order to fix the spoke to the hub, and on the other hand screw-thread to mount the spoke with a nipple to the rim.The quality of the spoke is determined by the weight, the strength, the corrosion resistance, the stiffness and the air resistance.

The material strength and the diameter of the spoke determine the strength of the spoke.
The spoke is weakest at the head which are inserted into the hub.
The bend of the spoke is under bending stress, making it quick to break.
In order not to weaken the bicycle spoke at the screw thread, the screw-thread is rolled on the spoke instead of cut.
Consequently, there are no sharp transitions in the thread.
For very different wheel sizes are tailored specifically spokes..

Cut for this purpose the spokes on the right length, install the correct roller head and roll the thread on the spoke.

The air resistance of round spokes is very bad.
This can be improved by a smaller diameter or by improving the shape.
Aerodynamic spokes are therefore used in aero wheels with high rim.
By a spoke to be carried out butted, the mass air resistance and stiffness can be reduced without this being at the expense of the strength.
After all, the weakest areas of the bicycle spoke were sitting at the head and the thread.
A butted executed bicycle spoke is even more strongly, because it is more elastic and therefore is better to be able for impact loads.
At the head gets a butted spoke less hits.

As the material of spokes is used almost exclusively steel.
Steel is pre-eminently suited to make spokes, as this has a high strength at a small volume.
Also, the head can well be forged into steel wire, and the screw thread can be easily rolled around .
For cheap spokes steel is galvanized or plated. More expensive spokes are made of stainless steel.
This material provides a very high tensile strength (2500N / mm²) by cold deformation during the production of the spokes.
With aluminum are currently no better spokes created.
To be as strong as a steel spoke, a aluminium spoke should have a wire diameter that is three times as large.
The air resistance is therefore three times as large.
In a wheel 36 spokes are generally employed.
At tandems are the forces on the wheel much greater. For this purpose, therefore, wheels are available with 40, 44 or 48 spokes.

The air resistance of a spoked wheel can be improved by as much as possible to omit spokes.
Combined with a strong and rigid rims there are aero wheels with 20, 18 and even 16 spokes.
Because the spokes are taxed much more heavily they also need to be a lot stronger .
Spokes for these wheels are therefore not provided with an angled head, but will be straight attached to the hub.

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