What is the best Bike Gear Ratio?
Not that the selection of bicycles is big enough – many bikes also have different ratios. But what exactly does “gear ratio” actually mean? Which ratio is right for my bike, the corresponding wheel size and personal fitness? And which ratio do I need for which situation – and can I change it if necessary? Here we help you to keep an overview and explain the most important features.
What is the bike gear ratio?
The ratio is the gradation of the gears, i.e. the combination of the number of teeth on the chainrings and the cassette. This decides how hard and easy you have to pedal. In combination with the circumference of the tire, you can calculate the corresponding transmission per crank revolution for each gear. The gear ratio can also be changed for hub gears. If you want to learn more about the different gear types, our guide will help you.
What is the bike gear transmission value?
There are certain standard ratio for each type of bike, which the bike industry has established over many years of experience. The built-in gear ratio should first be tested extensively. Newbies or inexperienced riders should pay attention to a particularly light gear ratio before buying a bike. If this is not sufficient, it can be changed as required. This adjustment can be easy, but before changing it you have to pay attention to some details that it will work properly later.
Attention should also be paid to the the transmission values which are the most important parameters for the calculation of the appropriate ratio. They tell you how much distance you travel per crank revolution. To do this, multiply the wheel circumference by the gear ratio (quotient of the teeth of the chainring and sprocket). In general, it can be said that gears with a deployment of less than 2.5 m are particularly suitable for mountain use. Developments in the range of 5 m are particularly good for slightly wavy regions, while around 7 m unfolding is preferred in the lowlands. The remaining deployments over 7 m are interesting for very sporty riders or downhills.
What exactly do you want to change on your bike gear ratio?
This question is very important. Therefore, you should be aware of what should be different in advance. If you currently own a bike, ask yourself whether the ratio is good or whether the gears are too difficult to pedal and you’d rather be easier; or are you running out of gears and you could actually ride much faster? Think about it and think about where and how you mainly use the bike. These factors play a big role.
What is a 48-36-26 crank and 11-34 cassette?
The manufacturers specify the number of teeth on the crank and cassette. This information is important to know how easy and difficult the gears are. When specifying the crank, you can see here first that it is a triple crank, since 3 details are given (48-36-26). Thus, the large chainring 48, the middle chainring 36 and the smallest chainring has 26 teeth. The gradation of the crank is thus known.
With the cassette, on the other hand, you will only find the information of the smallest and largest pinion. In this case, the smallest sprocket has 11 teeth and the largest sprocket has 34 teeth. The bandwidth of the cassette is thus known. However, you should still pay attention to how many pinions (gears) it has because it is possible that the 11-34 cassettes are available in different versions – for example, an 8, 9, 10, or 11-fold system. The more sprockets (gears) a cassette has, the finer it is graded within the specified range.
The perfect gear ratio for City / Trekking Bikes
In the field of trekking bikes, priority is given to the derailleur system with a triple crank. Since the trekking bike is designed for speedy driving in the countryside and also for uphill / downhill routes, it requires a wide range and a wide variety of gears. Here the two gradations 48-38-28 and 48-36-26 have prevailed. In combination with an 11-32 or 11-34 cassette, the range of gears is very wide. If this ratio is still too difficult for you, you can replace the cassette with an 11-36 and the crank with a 42-32-22, for example.
In city bike and urban areas, a lot is put on the hub gear. By limiting the number of trips to the city, it does not have to be as large as with a trekking bike. Nevertheless, you should also pay attention to which primary ratio is installed. If you are more comfortable on the road, it is advisable to choose a gear ratio with a small chainring (few teeth in front) and a large sprocket in the rear. If you are more sporty, a large chainring (more teeth in front) and a small sprocket can be preferred.
The perfect gear ratio for Mountain Bikes
In the mountain bike area, the selection of different variants is extremely large, everything is possible here between 1×12 and 3×11 circuits. Different ratios can be installed between different MTB types.
In the entry-level or low-cost segment, triple cranks, with the 40-30-22 teeth gradation and an 11-36 cassette, are still installed. This ratio has proven itself and should actually leave nothing to be desired.
In the sporting area, 1-speed and 2-speed cranks are ridden, in trials in some cases 3 times, but the trend is also 2 times.
The combination of 36-26 teeth in the front and an 11-42 cassette has established itself in the 2-fold variants. If this gear ratio is too difficult or too easy, chainring combinations such as 38-28 or 34-24 are possible.
1×11 is offered by both Shimano and Sram. Shimano offers this with an 11-42 cassette, Sram, however, with a 10-42.
The perfect gear ratio for Road / Triathlon Bikes
In the road bike segment, there are 3 crank gradations defined by the industry: the standard crank with 53-39, the semi-compact with 52-36 and the compact crank with 50-34 teeth. A compact crank is most often installed on road bikes, so a clear tendency of the area of use is defined. Here you can choose between several different cassettes: from 11-25 to 11-36 everything is possible. An 11-28 cassette is often installed, as this is a good compromise between light gears and a fine gradation.
The triathlon bike is designed for riding against the clock, so the ratio is usually chosen to be sporty. 53-39 or semi-compact cranks with 52-36 are often installed, combined with an 11-28 cassette. As with a road bike, almost all possible combinations can be used here.
The perfect gear ratio for Cyclocross / Gravel Bikes
The gravel bike usually has a compact or 1-speed crank with a larger cassette. 11-36 or even 11-42 are quite possible here and an ideal way to be fast on the road.
In the cyclocross area, 2-speed and 1-speed cranks are the measure of all things. Each has its justification as well as advantages and disadvantages.
The 2-compartment system is usually equipped with a gradation 46-36 and an 11-28 or an 11-32 cassette, so that it can be used for a very wide range of applications. You can customize this by changing the chainrings and cassette
In the sporty segment, the 1-fold variant is increasingly used. Here the gradation through the cassette is already more predetermined. Nevertheless, this can be individually adjusted again using the chainring. So you can choose between a 34 to a 42 chainring and so the ratio can be adjusted individually.
At the beginning we recommend a slight gradation of 38 teeth in combination with an 11-42 cassette. Heavier gear ratios are only recommended for very sporty riders.
What role does the rear derailleur length play?
As if it weren’t enough that there are different derailleurs for the different number of gears, there are also different lengths of the derailleur. In extreme cases, manufacturers offer up to 3 different derailleur lengths. These usually differ between short, medium and long.
Why the different lengths are required can easily be explained. The rear derailleur is not only responsible for the shifting itself, it also tensions the chain. The more gears the wheel has and the larger the cassette and the number of chainrings, the longer the chain must be. Accordingly, the rear derailleur must also be longer so that the chain can be tensioned sufficiently.
Finding out which rear derailleur is needed is easier than you think. Each rear derailleur has different information. In addition to the maximum largest pinion that can be ridden, the total capacity is also given. This is decisive whether the rear derailleur fits.
How can you calculate the capacity?
- Crank: The crank has a gradation of 42-32-22 teeth. Subtract the largest by the smallest chainring: 42 – 22 = 20.
- Cassette: You do the same with the cassette. If it has a gradation of 12-32, you also calculate here: 32 – 12 = 20.
To get the total capacity, both values are added. The total capacity is therefore 20 + 20 = 40. The shifting mechanism must therefore have a total capacity of 40 so that the gradation mentioned in the example can be carried out.
What about front derailleur?
The derailleur, like the rear derailleur, has different models for 2- and 3-speed cranks. Two important details are given here, the maximum number of teeth on the large chainring and the capacity of the derailleur. In contrast to the rear derailleur, the capacity of the derailleur only refers to the chainrings of the crank. With a gradation of 50-34 teeth, the front derailleur must have a capacity of 50 – 34 = 16. So you can see directly whether the derailleur is suitable.
What about the chain?
If you change the drive, the chain usually has to be changed too. This makes sense since new components are installed and the old chain is often too short and has already been in operation for a few kilometers. If the chain is too long, you could shorten it to fit the new drive.