How to choose Bicycle Sprockets & Chainring


Chainring - transmission units for the implementation of chain transmission of forces from the cyclist's legs to the rear wheel. The chainring for a bicycle is the main part - it simply won't run without it. Single speed models are supplied with a pair of chainring, master and slave. Bicycles with multistage transmissions are equipped with speed kits at the front (system) and at the rear with a ratchet or cassette.

The number and size of Chainrings determine the bike's flexibility in various road conditions. Thanks to the correct gear ratio, you can significantly reduce the energy consumption for the trip and travel at a comfortable speed. The durability of parts depends on the quality of the material, the riding style and the quality of service - with proper care, even the "initial" Chainring will run longer than professional, but neglected ones.

Gear Ratio Leading and Slave Chainring

Chainring on speed bikes is located on the right crank arm (driven) and rear wheel hub (driven). Through the chain, forces are transmitted from the front gears to the rear. Interestingly, the rear wheel, on the contrary, is the driving one, and the front wheel is driven.

 

Bicycle Square Hole Crank & Chainrings are levers that connect the pedal to the bottom bracket

Gear ratio is the difference between dimensions and number of teeth on the Chainring. This parameter directly affects the travel speed and transmission power. A high gear ratio is provided by a large drive and small driven gears, a low gear ratio, on the contrary, by a small front sprocket and a large rear sprocket. Accordingly, the gears on the classic transmission in the first case are 3 x 8, and in the second 1 x 1.

 

Thanks to the correct gear ratio, you can significantly reduce the energy consumption for the trip and move at a comfortable speed

The larger the front chainring, the higher the speed. For example, there are 44 teeth on the front for the chain engagement, on the back there are 11 teeth. For one revolution of the pedals, the rear gear will make 4 revolutions. If we take gear 22 to 11, then only 2 wheel revolutions will be made here per pedal rotation. At low gears, the opposite situation is observed: in front of the chain stands on a 22-gear gear, and at the rear on 32. The gear ratio is less than 1, that is, the wheels do not have time to turn completely in 1 pedal revolution.

High gears are designed for fast travel on a flat road. On hills, in headwinds and in poor road conditions, lower gears are used - the speed of the bike is lower, but more power and less energy consumption. Medium Chainring ratios such as 2 x 5 and 2 x 6 are often used.

Each Chainring system has its own cassette range. It can "float", that is, the same reverse gear applies to two Chainring systems at once, but, in principle, the pattern is as follows: 

 

diagram of gear ratio in bicycle

What do we have for single speed bikes? There are only a couple of gears, the classic gear ratio is 2. Corresponds to the average performance on high-speed models, intended for movement on asphalt, compacted soil, conventionally acceptable on short climbs.

You can increase the speed of a single speed bike yourself if you put a larger diameter Chainring in front. For frequent slides, it will be more relevant to increase the size of the rear gear.

And finally, how the programs are numbered. In the Chainring system they are arranged in descending order, on cassettes - in ascending order. The outermost gears are the highest gears, the inner ones are the lowest. The smaller chainring corresponds to the first gear in the cassette, the last gear. The number of stars in front and behind determines the gearing of the transmission, for this we multiply the numbers:

1 x 7 = 7 gears;
3 x 7 = 21 gears;
3 x 8 = 24 gears;
3 x 9 = 27 gears.
Etc. Do you need so many "speeds" in practice? It all depends on the riding style and the area of ​​use of the bike. However, it is important to choose the correct Chainring - this way they and the chain will be subject to less wear and tear, and the rides will be more comfortable. And if the transmission allows you to select the gear with maximum accuracy, then this should be done.

 

Oval Chainring Narrow Crankset Plate

 

An elliptical drivetrain pays off when you have to pedal at low cadence. Compared to the round counterpart, it provides some advantage in accelerating the bike from a standstill. There is also a change in gear ratio without shifting.

Types of fixing chainring on the cassette

Let's go back to the classic round cassettes. Unlike ratchets, they differ in the type of attachment to the drums. Bicycle cassettes are:
collapsible on a single drum with separators;
on a spider;
on blocks (several spiders);
Open-Glide;
X-Dome.

The first type of cassette is the simplest - all chainrings are mounted on a single spline drum. They are separated from each other by partitions - spacers. The disadvantage is the constant load on the drum. But the indisputable advantage is that they are easy to disassemble and change one chainring. They are easy to clean, but the components are more likely to get dirty.

Spider is a light version of a collapsible cassette. The load on the drum is not so big - here it comes not from every chainrings, but only from the spider's spline mount. These cassettes are lighter and less likely to get dirty.

you don't have to fiddle with spacers for a long time and lay out the entire cassette

The multi-spider design includes multiple pairs plus small chainrings individually attached to the drum. The model is very convenient because the new block is easy to pick up and, unlike a collapsible analogue, you don't have to fiddle with spacers for a long time and lay out the entire cassette. The development of this thing belongs to the Japanese parts manufacturer Shimano.

The Open Glide is a one-piece set that fits onto the largest gear. Unpretentious model: thanks to high-quality material, less wear and tear, long service life, low weight. However, cleaning a heavily soiled cassette is problematic.

The X-Dome system is represented by a similar design. Here, both the big and the small stars are in contact with the drum. A solid-milled block of 7-8 stars is mounted on them. Both Open-Glide and X-Dome are owned by SRAM.