How To Choose The Right Chainrings | Bike Components 2020

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Categories: Bicycle Repairing
Whether it is a mountain bike or a road bike, for different people, different riding environments, and different riding methods, there will be different chainrings selection.

Therefore, when purchasing chainrings, we should choose according to their own actual situation.

Chainrings Selection Rules

1. The number of teeth used now is the same as the number of teeth purchased, otherwise, the front gear should be replaced;
2. Pay attention to the same spacing of BCD holes, and the diameter of the chain wheel hole is required to be 10 mm, otherwise the chain wheel screw shall be replaced;
3. Pay attention to the ratio of big and small teeth of three discs. The common ones are 22-32-44,24-34-42,24-32-42,28-38-48,If not according to this gear ratio, it will affect the speed change;
4. Generally, 7 / 8 / 9-speed disks can be universal if the number of teeth is the same, but 10-speed and 11-speed chain wheel cannot be universal;
5. Replace single speed chainring, it is only necessary to select the appropriate number of teeth, regardless of the speed category.

Explanation of Terms:BCD
A circle surrounded by five mounting holes normally distributed, the diameter of this circle is BCD. The BCD is 130mm according to the standard jointly developed by Shimano, SRAM, and Dahang.

General Gear Plate Rules Reference:

NameBike ChainringBike ChainringBike ChainringBike ChainringBike Chainring
Specifications45T47T53T56T58T
BCD130mm130mm130mm130mm130mm
Diameter195mm205mm225mm235mm245mm

-The larger the number of teeth and the larger the diameter, the faster the relative riding and the more laborious it will be;
-When selecting a chainring with a large number of teeth, please make sure that its diameter will not rub the frame, otherwise, it is necessary to replace a longer central shaft;
-The compatible chain speed category is 9 / 10 / 11 speed. In addition, the chain must be lengthened when replacing chainring with a large number of teeth;
-Make sure the BCD is 130mm before purchase.

Suggestions For Number Of Sprocket Teeth Selection
For the 14 / 16 / 20-inch folding bike, each size has a common choice for the number of teeth in the chainrings.14-inch folding bike is generally 45/47t,16-inches bike, generally no more than 53t,20 inches bike generally no more than 56t. Of course, it can be adjusted according to personal conditions.

Description Of Positive And Negative Teeth
With the appearance of a single chainring, the positive and negative tooth chainrings emerged. As shown in the figure below, the teeth of positive and negative teeth are designed as one big and one going to the countryside alternately, which can limit the chain position, so as to reduce the probability of Chain dropping.

For the positive and negative teeth, the width of the tooth top is large, the tooth height is high, the chainring is thick, the chain can be moved, and the gap is smaller, which can prevent the chain from falling to the greatest extent.

Precautions For Chainring Installation:
1. Distinguish the positive and negative sides of the chainring: the front is smooth in appearance, and the back is with steel seal font;
2. Distinguish the chainring direction, as shown in the figure below:

The Size Of Chainring Teeth Is Not Uniform
A careful observation of the teeth of the chainring revealed that some teeth were pointed, some teeth were blunt and shorter. This design is to make it easier for the chain to leave or fit the chainring when changing speed so that the speed can be smoother. It is not a defective product.

Both large and medium chainrings have such uneven tooth designs, while small ones are uniform.

Question1:
Why is the disk nail hole of the middle chainring of 10 mm and the big chainring is 8mm, but can we share one disk nail?

Answer:
The screws are divided into screw cap and nuts, The diameter of the screw cap is generally about 9.98mm, which just passes through the hole of 10mm, the diameter of the nut is about 7.88mm, which just passes through the 8mm hole. Therefore when screwing, one side of the screw cap goes through the middle chainring and the nut goes through the large chainring, which is just fixed.

Question2:
Why is there such a big price difference between 9-speed and 10-speed aluminum alloy chainrings?

Answer:
First of all, there are differences in materials,7075 aluminum alloy is used for 10 speed, 6061 aluminum alloy is used for 9 speed.
Secondly, the 10-speed chainring processing method is to use a whole piece of aluminum, processed by the CNC machine tool, the cost is relatively high. And the 9-speed aluminum chainring is first stamping aluminum sheet forming, and then CNC machine tool edge, cheaper.

Question3:
Why can’t 9-speed chainrings be used in 10 Speed chainrings?

Answer:
First of all, the difference between speed 10 and speed 9 is mainly the width of the chain, which determines the thickness of the teeth. 10-speed chain sleeve 9-speed teeth, the chain can not fully fit the chainring, so it is recommended not to be universal.
Secondly, the chainring itself also has a radian (it is difficult to reflect this point when taking pictures), and the radian of 10 speed and 9-speed chainrings are different.