Headset (bicycle part)
A tax rate of the steering head bearing is designated for bicycles, so the bearing in which rotates the steerer.
Construction
The bearing housing is the head tube. Two bearings run in the steerer tube. The outer rings of the bearings are pressed in as a rule in the control tube. The inner race of the lower bearing is usually pressed onto the steerer tube, screwed to the inner race of the upper bearing depending on the version of the steerer tube or fixed by a conical seat.
Standard for simple bearings are angular contact thrust ball bearings, often abbreviated as ACB ( angular contact bearings ). At the upper price classes will also elaborate tapered roller bearings or tapered needle bearing use.
The sizes of the tax rates on bicycles are given in inches. The size corresponds to the outer diameter of the steerer tube. Today, almost all tax rates for the size 11 /8 inches (11/ 8 ") are installed worldwide, which greatly facilitates the procurement of spare parts. Meanwhile, there are reasons of stability also 11/2-Zoll-Steuersätze: A shaft bearing ( such a one is machine construction ) is more stable, the more the bearing points apart and the larger the bearing diameter.
By design, it is no longer easy to control sets of any manufacturer, to exchange against each other since the heights are different and thus the steerer tube may be either too short or would have to be sawed off.
Systems
Thread
For a long time tax rates common in which the rate was fixed by threaded the steerer.
Ahead
The Ahead system (protected brand name) used forks without thread. The tax rate does not have a tensioner. Instead, the voltage is regulated by a cap set, which is connected with a claw at fork. The claw must first be wrapped in the steerer tube; for carbon steerers contrast inner terminals are used, supplied by the fork manufacturer. After the bearing tension adjusting the stem is fixed, thereby keeping the tension.
This system is lighter than Threaded headsets, assembly is easier and the manufacturing of the parts is cheaper, because no thread has to be cut into the steerer. There are press-fitted bearing shells above and below the head tube of the bicycle. The bearings themselves are then in the bearing shells outside the frame.
Semi- integrated
In recent years the semi- and fully integrated tax rates came on the market, which reduced the overall height, but ensure, through the many different sizes of confusion.
Is semi - integrated often referred to as internal or Zero Stack ( ZS) respectively. Ahead of the difference is that the storage is located in the interior of the control pipe.
Fully integrated
Integrated headsets go one step further and abandon the costly press-fitting, which is usual with tax rates. The treads are already incorporated in the head tube with 36 ° or 45 °. The bearing shells can without special tools and without forcing be installed and include inside storage. The advantage of this system lies in the lower weight. There are so-called Micro Spacer with 0.25 mm thickness to compensate for the different heights of the individual manufacturer. This is intended to frame damage.
Conical (Tapered )
The latest generation of wheels has a so-called Tapered - tax rate system. Here, the control tube has up and down different Einpressdurchmesser. It must be the lower shell and the lower Einpressmaß be determined separately from the upper Einpressmaß. First, the control tube diameter must be above and below are determined, then the Gabelmaß must be measured above and below. Forks can be either a continuous steerer 1 1/ 8 " or 1.5 " or have a tapered version with a butted steerer tube from the bottom 1.5 " and up 1 1/8 " here.
From various manufacturers now many standards came on the market. Unfortunately, it's almost become unmanageable, which is compatible with each other because there's different bearing widths and bearing angle. Even the height of the bearing shells is different.
All measurements refer to the diameter in mm.