When it comes to gearing on a mountain bike, knowing your stuff goes a long way. You can really take the fun out of a good bike ride by having to jump off the bike and walk up a hill.
What could be even more frustrating is having your friends fly past you on the way down while your gears are spinning out.
Mountain bike gearing can be difficult to understand. It has changed a lot over the past twenty years. In this article, we want to tell you everything you need to know about mountain bike gears, covering:
- Why Is Gearing On A Mountain Bike So Important?
- The Parts That Make A Mountain Bike Gearing System
- What Makes Mountain Bike Gearing Unique?
- Speeds And Ratios
- How To Pick The Right Gearing For You
Let’s dive in!
Why Is Gearing On A Mountain Bike So Important?
When it comes to hitting the trails, having the correcting gearing is really going to improve the experience.
Here’s why:
#1. Speed
Having the correct mountain bike gearing means you can climb and descend efficiently.
Using the gears properly, you can easily control the bike at low and high speeds. Gearing is vital when it comes to performance. Races have been won and lost because of gearing choices.
#2. Pacing
Gearing on a bike lets you adjust the resistance you will be pushing against on the pedals.
It means you can keep the same cadence, whether climbing or descending. This makes it much easier to pace to maintain energy levels and properly maintain control.
#3. Ability
The gearing on a bike gives it the ability to tackle more challenging terrain.
Mountain bikes typically feature extreme gear ranges. This is so you can help keep control at low speeds and easily go over and around obstacles such as rock gardens.
What Makes Up A Mountain Bike Gearing System?
To properly understand gearing on a mountain bike, it’s important to understand all the parts that need to come together.
This next section will break down a mountain bike’s gearing system.
Crankset
The crank is what your pedals are attached to.
Here you can push the chain around the system giving life to the gears and propelling you forward. These come in all different sizes, from crank arm length to amount of teeth on the chainrings.
Cassette
The cassette sits on the rear wheel and is connected to the crankset through the chain. This cassette has various cogs where you can put the chain to give you different ratios.
- Want to know more? Check out our Complete Guide to Bike Cassettes here!
Chain
The chain connects the whole system together, transferring power from the pedals to the rear wheel. It sits on the crankset and the cassette and is guided by the derailleurs.
Derailleurs
The derailleurs guide the chain around the system to give you different ratios. Bikes either come with one or two derailleurs. You will always find one at the rear cassette. If you have multiple chainrings, you will also have one at the front above the crankset.
- Want to know more? Check out our Complete Guide to Derailleurs here!
Shifters
Finally, you have shifters.
When combined with the brake levers in a single unit, these are sometimes referred to as “brifters” – a mashup of “brakes” and “shifters”. However, brifters are primarily seen with drop handlebars, so are far more common on road and gravel bikes than mountain bikes.
What Makes Mountain Bike Gearing Unique?
Gearing on a mountain bike differs greatly from other cycling disciplines, such as road cycling.
Here’s what makes mountain bike gearing unique:
#1. Trigger Shifters
Mountain bikes often use trigger shifters. These are excellent because they allow you to change gears while still having a full grip on the handlebars.
They often are also separate from the brakes, unlike other shifters.
#2. Low and Wide-Range Gearing
Mountain bike groupsets are designed to be used at much lower ranges compared to road bikes or time trial bikes.
They also have a very wide range of gear ratios for climbing and descending.
#3. Made For Rough Terrain
Mountain bike groupsets are made to take a good shaking.
They’re much more rugged than road bike groupsets. Many come with clutch mechanisms and are much better over rough terrain.
#4. A Lot More 1x Drivetrains
One thing you do see more in mountain biking is 1x drivetrains. They are much more suited to off-road riding than 2x or 3x systems. You only really see 1x systems in MTB or gravel – although SRAM does offer some 1x road bike groupsets.
Speeds and Ratios
When it comes to gearing on a mountain bike, there are two things you need to take into consideration, speeds and ratios. These are what matter, and you can tell a lot about a groupset by doing some simple mathematics.
Speeds
There’s a common misconception about gears for a mountain bike that the more speeds (gears) you have, the better the groupset will be and the more range it will offer. This couldn’t be more wrong, and understanding gears is much easier than you might think.
Speeds are how many different gear ratios the bike will give you. For example, a 1×11 groupset will give you 11 speeds, and a 2×10 groupset will give you 20 speeds.
Over the past 50 years, mountain bikes originally started with around 10 speeds and built up to 27 speeds or more. Now, the trend has returned to using fewer speeds. Modern high-end mountain bike groupsets now generally have around 13 speeds on a 1×13 system.
Having more gears gives you many different options to play with, but it doesn’t always mean you’re getting more range.
To explain this further, we need to speak about ratios.
Ratios
Ratios are the different combinations you can get from the speeds. The two most important things to consider are the lowest and highest ratios. These give you your most extreme gears for climbing and descending.
We work out ratios by taking the size of the front chainring or chainrings and dividing it by the cogs on the cassette. You can use our Gear Ratio Calculator here.
The lower the ratio number, the better it will be for climbing. The higher the number, the better it is for descending and higher speeds.
Comparing Speeds and Ratios
Now for the fun bit, let’s take two groupsets that have different speeds and compare the ratios they give. We are going to look at the SRAM NX Eagle Dub and the Shimano Deore. As we mentioned before, we’re looking for the lowest and highest ratios.
| Groupset | Speeds | Lowest Ratio | Highest Ratio |
| SRAM NX Eagle | 1×12 (12 Speeds) | 0.64 | 2.91 |
| Shimano Deore | 2×11 (22 Speeds) | 0.62 | 3.27 |
This tells us that although the 2×11 Shimano Deore might have nearly double the number of gears compared to the 1×12 SRAM NX Eagle, it doesn’t have double the range.
Regarding climbing and low speeds, they both have very low gearing at 0.62 and 0.64, which means they are very similar in ability when it comes to going uphill.
When it comes to descending and high speeds, the Shimano Deore does have more, with a 3.27 compared to a 2.91. This is only about 10% more gearing on the upper end.
So although speeds do give you more options, it doesn’t always mean you are getting much more range and ability.
- Want to know more? Check out our Ultimate Guides to SRAM MTB Groupsets and Shimano MTB Groupsets here!
How to choose the right gearing for you
Finding the right gears for a mountain bike can be challenging. There are a lot of different groupsets to choose from and some amazing brands. Here’s what you need to be thinking about:
#1. Compatibility
You need to make sure the groupset you buy will fit your bike. Not all bikes and groupsets are compatible. It’s also worth checking the sizing with the frame manufacturer to ensure it can fit parts such as larger or multiple chainrings.
#2. Budget
Mountain bike gearing comes in all different price ranges. You can get basic gearing for as little as $200, or you can easily spend $2000 on advanced gearing.
As with all bike parts, mountain bike groupsets have diminishing returns as they increase in price. There are plenty of decent-quality groupsets towards the lower end of the scale – they might not win you any World Championships, but they’ll get the job done!
#3. Maintenance Costs
If you really splash out on an electronic groupset with incredible performance, it will cost more to maintain.
You will typically spend 15% of the cost of the groupset each year just maintaining it if you ride it regularly.
#4. Ratios
We highly recommend checking the gear ratios before buying a groupset. Although you might think you have found the perfect groupset, it could be completely wrong for the riding you want to be doing.
#5. Brand
Regarding gears for MTB, we highly recommend going for a big-name brand such as SRAM or Shimano. They are excellent quality, spares are easy to get, and they undergo extensive testing before being released to the market.
#6. Discipline
Gears for MTB can sometimes be designed for certain mountain bike disciplines. You need to ensure that you get the right groupset for your riding. The last thing you want is a heavy downhill groupset while riding cross-country!
