To facilitate a better understanding of the new and mountain Utility Vehicles riders all parts of the central axis of this article to shimano, dental plate as an example, explain to you riders under the central axis of each tooth plate classification and definition of the term

A: axial square hole, square hole cranks

This is the most common type of bicycle bottom bracket, crankset type, shimano square hole axis number begins with un, so we see that un shimano bottom bracket starts with the model, you can determine this axis is a square hole axis

The figure is a suite of standard shimano's alivio axis: un-25
II: spline shaft, spline crankset

Splined shaft, the power distributed to each spline on the central axis of the tooth plate, and tolerance to do with the better. Reasonable efforts have been scattered, the gap is reduced. Contact area, the force transmission performance the better. shimano splined bottom bracket usually start ES

The figure is a suite of standard spline alivio axis: ES25
Third, the integrated structure of the central axis, two-piece crank structure (two-piece crankset)

The structure of the tooth plate, the central axis relative to the old section of the square hole, spline system is a qualitative leap, whether square or splined hole, when they were pedaling axis and the role of dental plate, shaft and bearing role . These two stress. And one axial and two-piece cranks, shafts and cranks are fixed, the right foot force, only the shaft and bearing role. This reduces the dispersion of power consumption, so the power transmission with good performance. Road vehicles in this area is particularly reflected. And integrated axis on both sides of the axis spacing wider, improved rigidity.

Many riders to-one axis, two-piece crankset that is integrated into a dental plate, in fact, this is not true, but because of one style and two-piece tooth foldable electric bikesaxis drive can not be separated, so referred to is understandable.

shimano-one BB axis number usually begins with the following figure is shimano deore's integrated suite of standard axis: BB51

The figure is deore kit standard FC-M590 crankset

Four: hollow crank

We see the traditional crank to alivio the tooth plate to for example, is hollowing out the inside of the crank to reduce excess weight, do so at the same time, the crank on the formation of stones in the stampede easily distorted deformation, of course, this deformation is very subtle, that is, when the stampede that is not hard, soft.
The principle is the hollow crank technology, taking the middle, while in weight, force multi-faceted, not prone to subtle distortions, improve the efficiency of stampede.
We can give an example to illustrate the usual, if it is holding an iron, it is easier to make the deformation, if it is the same thickness of iron pipe, not easily deformed.

alivio hollowed out tooth crank disk

Real hollow crank

It is worth mentioning that, shimano splined bottom bracket system also introduced a hollow crank crankset, this crankset is relatively rare.
The following picture shows the FC-M521 crankset