How to Choose the Ideal Derailleur for Your Mounting Bike
Maybe you’re looking to change your riding style. Perhaps you’ve managed to break your old derailleur. Whatever the case, you need to compare your options and make an informed decision. That can be pretty challenging thanks to the wide range of different options on the market, and if you lack a lot of experience, it only gets more difficult. The good news is that it doesn’t have to be a chore. Understanding a few key factors will help you find the right mountain bike derailleur with less time spent and less hassle. We’ll break down everything you need to know right here.
Number of Gears
One of the most critical considerations when choosing a new derailleur is the number of gears it is designed to work with. This will hinge on things like the type of bike you have, the type of chain you have, and the type of cassette that you’re using. Simply put, a 10-speed derailleur will not work with a 9-speed cassette, or a 12-speed chain. Each of the components in the system must be the same.
With that being said, if you really want a particular derailleur and it’s not compatible with your current setup, you can change that. You can purchase new shifters, a new chain, and a new cassette and give your mountain bike a major facelift. However, that’s a lot of work, and for most people, the better option is to simply stick with what you had previously.
If you were paying attention to our list of the best derailleurs for mountain bikes, then you noticed that all but one of them were for the rear of the bike, not the front. When replacing your rear derailleur, you do need to make sure that you’re getting something that is compatible with the front derailleur and with your shifters. This goes beyond buying a model designed for the number of gears your bike has, though.
Most rear derailleurs are very specific and must match the chain, cassette, shifters, and front derailleur. Usually, this means purchasing one from the same company that made your other components. You will also likely need to purchase a derailleur from the same line as the rest of your components – the SRM Eagle, for instance, or the SRM Red group set.
Your only other option, as mentioned in the section above, is to do a complete overhaul on your entire drive system.
You will have noticed that there were short, medium, and long cages listed with our rankings of the top derailleurs. What does that mean, though? It applies to your chainrings. If you have a triple chainring, then you want a long cage. If you have a double chainring, then a medium cage is better for you. Finally, if you have a single front chainring, then you’ll need a short cage.
A wide range of different materials can be used in making mountain bike derailleurs. In our list alone you saw carbon fiber, steel, aluminum, titanium, and magnesium. Each of these has something different to bring to the table:
- Aluminum – Lightweight, strong, and durable, aluminum can be used for just about every part of a derailleur except for the springs in most cases. Forged aluminum and aluminum alloys offer outstanding performance and durability, but for less money than some higher-end materials.
- Steel – Steel is very strong and very durable, making it a great choice. However, it can also be pretty heavy, which means that when it is used in derailleur construction, it’s a little limited. Usually, only components that need high-tensile strength are made from steel, such as cogs and springs.
- Carbon Fiber – One of the newer and most popular materials in the industry, carbon fiber is super light and very strong. It’s also the most expensive option out there, which is why only two of the models we listed are made from it. While it can provide superior performance and weight reduction, the cost alone often puts it out of reach for many riders.
- Titanium – Titanium is very, very strong and, thus, exceptionally durable. You’ll find it used in a number of different ways within derailleurs where strength and resilience are needed. It is also relatively light, although not as light as carbon fiber.
- Magnesium – Magnesium is light but strong, and is sometimes used for spring manufacturing. Only one of the derailleurs on our list uses this metal in its makeup, though.
Ultimately, there is no perfect construction material. Each is a tradeoff. Some are light but weak, while others are strong but heavy. Carbon fiber is light and strong, but it is expensive. You will need to find the right combination of materials to deliver a durable, reliable derailleur that fits your needs and your budget. However, there’s something on our list for just about everyone.
Weight may or may not be a big consideration for you, particularly when we’re talking about just a few grams. However, some riders put a lot of stock into weight reduction, and are willing to pay lots of money for the lightest components on the market. Our opinion is that weight doesn’t really make much of a difference unless you’re racing.
Let’s face it. You’re more than a little limited when it comes to derailleur brands. There’s Shimano, and there’s SRAM. Campagnolo is also around, but the Italian company’s mountain bike-specific offerings are few and far between, although we did include one derailleur on our list. Most Campagnolo products are focused on racing, rather than mountain biking performance.
Is there a better brand? It’s actually more about personal preference than it is about quality or performance. SRAM is supposed to provide a snappier shifting performance according to some people. Shimano has a number of other attributes. Again, it is more about personal preference in terms of brand adherence. However, you cannot usually mix and match derailleurs and other system components, so even if you want to try out Shimano, if your bike is outfitted with SRAM components, then you’ll need the appropriate SRAM derailleur. Either that, or you’ll need to complete a drivetrain overhaul.
Each mountain bike derailleur we covered includes some type of clutch. This is an innovative solution to the challenge of keeping the chain on the gears through hard use, riding over bumps, and encountering other obstacles while on the trail. The clutch helps keep tension on the chain to keep it firmly seated, but there cannot be too much tension, or shifting would become a major issue.
You will find a very wide range of clutch technology out there. Shimano’s most famous is the Shadow Plus clutch, which can be found on several of the derailleurs we listed. SRM has type 2 and type 3 clutches. Other companies have yet other designations and technologies. When comparing your options, you want to look for capabilities like clutch locking, which makes changing wheels simpler, as well as shifting ease and tension capabilities.
Tuning and Adjusting
All derailleurs will need some amount of adjusting and tuning to get them just right for your riding preferences. Each is different. SRAM is reputedly somewhat challenging to tune and adjust, while Shimano has a reputation for being less time and labor intensive.
Should You Go Electric?
Before we even talk about electric shifting, let us be clear – all of the derailleurs covered in our list are mechanical, not electrical. Electric shifting is something relatively new, and it offers greater precision than what mechanical shifting can offer. That’s good news for a lot of riders. It has also spread from the world of racing into mountain bike riding.
With all of that being said, electric components are very expensive, with a minimum starting point of over $1,000. You will also need to rebuild the entire system, as electric derailleurs only work with electronic shifters. However, if you’ve got the bankroll and really want to try out the newest of the new, you’ll find electronic components available from both SRAM and Shimano. For the rest of us, mechanical shifting will be the way to go for some time.
In the end, the right derailleur for your mountain bike is likely going to be an exact replacement for the one you’re replacing, or will be compatible with your existing equipment. Remember that in most cases, mixing and matching is not possible. You’ll need to use the same brand for your derailleur as for your shifters, for instance, and often you’ll need to shop from within the same production line. However, it is possible to complete rebuild your drivetrain from the ground up if you really want to try out another brand or another line from your current brand.