When you buy a new carbon frame you also need to think about the components you’ll want to install on your bike and more specific what groupset you’ll want to use. But looking at all these components it’s easy to get confused, certainly for novice mountain bikers. In this guide we’ll do our best to explain the groupsets and their usage of the two major players in the business – Shimano and SRAM. We’ll also give a couple of alternative options in the end but for now let’s get started.
What is a groupset?
Simply put a groupset are all the mechanical parts you need on your bike to accelerate and decelerate. This includes:
- Cassette
- Derailleur
- Chainset
- Chain
- Shifter
- Bottom bracket
- Brakes
Manufacturers categorize their groupsets by name into different levels of price and performance which creates a certain hierarchy. This gives the consumer a simple way to recognize what kind of performance to expect from a groupset.
Cassette
One of the main components on a MTB groupset is the cassette, it consists of a cluster of metal discs with teeth around the edge, called sprockets. All these different cogs, ranging from small to large will give you the amount of gears. The size of these sprockets is referred by the number of teeth they have. The largest cogs are closest to the wheel and the gears are numbered from the inside out. The larger the cog the ‘lower’ the gear and the easier it will be to pedal, but the slower you will go. For example a cassette can be sized as a 11-48t which means the lowest gear has 48 teeth and the high gear has 11 teeth.
This component immediately catches your eyes on the rear wheel as modern mountain bikes usually have a large 12- or 11-speed cassette. Although on more entry level bikes you’ll most likely find a 10- or even a 9-speed cassette.
A fair warning, if you ever wish to upgrade your cassette make sure to check the compatibility of your freehub. Most 12-speed cassettes have their propriety freehub system (Microspline for Shimano, XD for SRAM).
Derailleur
The next eyecatcher on your drivetrain is your derailleur. Your derailleur or ‘mech’ is a sprung activated mechanism that moves the chain smoothly, reliably and efficiently across all the gears on your cassette. The spring in your rear mech helps to keep your chain under tension and minimize chain slap. Most modern mechs come with a ‘clutch’ system which minimizes chain slap even more.
The size and capacity of your rear derailleur is obviously dictated by your cassette. Most commonly you’ll find long cage rear mechs with modern larger range cassettes because your rear mech has to be able to accommodate the gear range of your bike. A short cage mech is more common on a downhill bike where the cassette is much smaller.
Chainset
A chainset consists of multiple components: crank arms, an axle and a chainring. Most modern mountainbikes will only have a single chainring, a so called one-by system but on low-end and entry-level bikes it’s not uncommon to find 2 or 3 chainrings.
Chainrings come in a variety of sizes and are measured in the number of teeth the ring comprises. Simply try to remember, the more teeth a chainring has the harder it is to pedal but you’ll have more speed. The smaller a chainring is the more efficient you’ll climb. When replacing a chainring for a larger one, always make sure your bike has enough room to accommodate it.
Crankarms, the part where you attach your pedals, will also vary by groupset. With every step you go up the groupset’s ladder the lighter it gets. The high-end models are even made out of carbon. The length of the cranks can very depending on the rider’s height or preferences. Most commonly a 175mm crank is used but shorter cranks exist too (170mm or 165mm). A shorter crank is easier to pedal, for shorter riders and reduces the risk of rock strikes.
Chain
One of the most important components on your bike is your chain. It links your chainset with your cassette and enables you to accelerate when putting down the power on your pedals.
And yes, even chains are groupset specific. The higher you go up in the groupset the more expensive the chains are but then again you’ll get better technology. The chain will be smoother, more durable, have a special coating and will be lighter with hollow links.
Keep in mind that your chain is a wearable item on your bike, to keep your drivetrain in perfect condition you’ll have to change it once there is too much chain stretch. When replacing your chain make sure the number of speeds match your cassette. You can’t put a 10 speed chain on a 12-speed drivetrain, the chain links will be to wide for the space between the sprockets on your cassette which will wear it down much faster.
Some chains even have technology that is brand specific, for example Shimano has their hyperglide + that you can only get on a complete Shimano drivetrain – chain included.
Bottom bracket
A bottom bracket is pretty simple to explain, but perhaps a bit harder to understand. Think about it as a shell with two large bearings at each end. The axle of your crankset passes through this shell and the bearings help you spin your cranks nice and smoothly. There are two sorts of bottom brackets, a press fit bottom bracket or a threaded bottom bracket. For each one of them exists proprietary tools for installation. Also if you shop around for a new bottom bracket, be sure to check the inner diameter of the bearings, not all bottom brackets are compatible with your cranks. Shimano has their Hollowtech system which is a 24mm axle, SRAM has their DUB system which is a 29mm axle.
If you’re not sure what bottom bracket system to install or you do not have the necessary tools, you can always go to your local bike shop for help.
Shifter
The shifter is the mechanism that is attached on your bars to change your gears on your cassette. It is attached with a cable onto your derailleur and with a push of your thumb you can down-or upshift. Almost all bikes come with a “trigger style shifter”, this means there are two levers that can be either pulled or pushed to change gears. On some cheaper bikes you can still find a “gripshift”, with these style of shifter you need to twist you’re a part of your grips to change gear.
Just remember, shifters from high-end groupsets will let you downshift (move your chain to a bigger cog) multiple times with one thumb push (up to 4 gears at a time), whereas lower end shifters only let you shift one gear at a time.
Brakes
Once a wise man said: “in order to go fast you need first to slow down”. Unfortunately brakes are not given the much needed attention they deserve as they are one of the most essential parts on your bike. They give you the control and safety on your bike.
On older frames you’ll usually see rim brakes, on more modern bikes you’ll most likely find disc brakes (either mechanical or hydraulic).
Here there is a difference between Shimano and SRAM. SRAM labels their brakes depending on the intended use. Shimano on the other hand offers for every MTB groupset a hydraulic brake option.
2.Shimano MTB groupsets
We ordered Shimano’s mountain bike groupset hierarchy, from least expensive and technologically advanced to most:
Recreational MTB groupsets:
- Shimano Tourney
- Shimano Altus M2000
- Shimano Acera M3000
- Shimano Alivio M3100
The first 4 groupsets from Shimano are not off road-worthy, they lack the durability of regular trail abuse. You’ll find these groupsets mostly on children’s bikes or on cheap entry level mountain bikes. These groupset consist of a 6-, 7-, 8- or a 9 speed cassette usually paired to a triple or double crankset, Depending on its intended use. Although you can consider Alivio as the starting point for the MTB groupsets
XC / Trail / Enduro groupsets:
- Shimano Deore M6100, M5100, M4100
Deore is the first real MTB groupset. This groupset recently had big overhaul, thanks to all the tech that trickled down from the XTR and XT range.
This groupset features a 1x12 only and a 11 or 10 speed cassette that can be set up as a 1x system or as a 2x. Remember the 1x12 cassette needs a Microspline freehub, the 11- and 10 speed cassette use a regular HG-freehub.
- Shimano SLX M7100
The SLX groupset is to me one of the most important in Shimano’s lineup. It benefits from all the technology coming from the upper-end groups while still being affordable. The only downside on this groupset is the slightly higher weight and a bit slower shifting. Personally, I think this is the best entry-level drivetrain you can get in the Shimano hierarchy. My tip: pair a SLX drivetrain with a XT shifter for the best performance for your bucks.
- Shimano Deore XT M8100
Shimano Deore XT sits just below the top tier group. It is the first groupset Shimano ever created and is considered to be the workhorse in the range . This group benefits from nearly all the top-end performance features as XTR, only with a slight weight penalty. It gives everything a rider wants for a slightly higher price.
Deore XT is available with a wide range 10-45 or 10-51t 12-speed cassette for 1x and 2x drivetrains.
- Shimano XTR M9100
XTR is Shimano’s ultimate MTB groupset and is mostly used by their sponsored athletes. It combines light-weight materials and all of the latest technology Shimano has to offer. It is normal to find certain features first on this high end groupset before it trinkles down to the other groupsets.
In the past XTR was split into multiple categories but the latest update in this series got the groupset condensed into the same line, though you can still find different parts for XC or Enduro. Brakes and brake rotors for example come in different forms, there are as well 4-piston brakes as there are lighter 2 piston brakes and the brake rotors go from 140mm al the way up to 203mm.
The groupset also has multiple drivetrain options going from a massive 1x 12 10-51t cassette to a 2x11 10-45t cassette.
Downhill groupsets
- Shimano Zee M640
Zee is Shimano’s entry level discipline specific groupset, it is the perfect place to start if you are new to downhill. It is more affordable than the Saint but, again, it means a higher weight. The groupset only comes with a 1x 10 speed drivetrain
- Shimano Saint M820
This is the top tier group for any downhill racer. It is built sturdier, lighter and is able to handle any abuse thrown at it.
SRAM MTB groupsets
Recreational MTB groupset
- X3
- X4
- X5
These groupsets can be very well compared to the Shimano recreational drivetrains. They are not meant to be ridden full time on the trails and are mostly found on entry-level bikes.
XC / Trail / Enduro groupsets
- X7
The most basic and cost effective MTB groupset that SRAM has to offer. The most important feature to remember on this 10 speed group is the rear clutch mechanism.
- SX Eagle
SRAM is a younger company within the MTB sector but one of the more progressive manufacturers. Proof is the introduction of the the 1x drivetrain and 12 speed cassettes whom became the standard within a few years. The American manufacturer branded all of their 12 speed range options as “Eagle”.
The SX Eagle groupset is in my opinion SRAM’s first true MTB groupset. It is the most affordable groupset within the Eagle range and this comes with its limitations. It is the heaviest in the range and the cassette sits on a normal HG freehub which limits the smallest cog to 11t Starting from GX and above this is a 10t cog.
- NX/NX Eagle
NX brought the 1x11 shifting to a greater public, you can still find this groupset mostly on mid range bikes although NX Eagle being the more popular option. The NX group has excellent performance and takes advantage of all the higher range technology that trickled down.
NX Eagle stands between the GX and SX Eagle drivetrains and offers a better derailleur than SX Eagle with Type-3 Roller Bearing Clutch technology and a lighter cassette.
- GX/GX Eagle
The next addition is the most popular in SRAM’s lineup. GX and Gx Eagle bring the best of both worlds, great performance at an affordable price. First the GX was introduced with a 1x11 drivetrain and even better shifting performance. Later the GX Eagle used even more engineering from SRAM’s high-end 12-speed groupsets.
In 2020 GX Eagle got a major update: the cassette had an increase in teeth going from 50 to 52t on the lowest gear, the derailleur adapted to the new cassette – it needs to shift into the lowest gear. And there are two versions of the cranks, a carbon and an alloy one.
- X01/X01 Eagle/XX1/XX1 Eagle
These are SRAM’s flagship drivetrains. I’ve put these groupsets together because they are almost identical. The main difference between these groupsets is weight. Where XX1 utilizes the lightest materials possible, for XC racers it is the top-end group, X01 is more durable with a bit heavier materials and a sturdier construction. You’ll find this group on high-end trail and enduro bikes.
Although the technological DNA is identical on both groupsets there are some slight differences. The X01 has a full aluminum derailleur cage whereas the XX1 uses a carbon outerplatet. The cranks have a foam core whereas the XX1 has hollow carbon cranks.
Both groupsets received the same update as the GX Eagle, with a larger cassette and compatible mech.
Downhill groupsets
- GX DH
This is SRAM’s budget option for downhill racing. It is a seven gear groupset which only features a shifter, mech, chain and cassette.
- X01 DH
X01 DH is SRAM’s top of the line downhill groupset. It comes as a full group, either with a 7- or 10-speed cassette.
Electronic shifting
The latest and greatest development is electronic shifting. Shimano has developed their Di2-system and SRAM names their wireless line AXS (pronounced access). Normally you simply shift up and down your cassette with a cable actuated shifter. Electronic shifting gets rid of the cable and uses Bluetooth signals to actuate the shifter and derailleur.
We don’t need to tell you this premium product comes with a steep price tag. This year SRAM released the GX AXS system for almost half the price of an XX1 or X01 AXS system.
Why upgrade to electronic shifting?
- No or not much cables to be routed – SRAM AXS system is completely wireless? Shimano’s Di2 do have some wired cables
- Precise shifting, with every shift
- The shifter’s lever is a lot easier to manipulate
- Lot’s of information to be found in the apps about shifting habits
Are there any downsides?
- It is battery operated, if you run out you can’t shift anymore.
- Adds a certain level of complexity in new ways
- The cost will leave a big hole in your pocket
Some alternative manufacturers
Shimano and SRAM are the biggest players on the MTB component markets, but there are other options on the market.
Microshift
Microshift is a Taiwanese drivetrain manufacturer, fairly new to the market. Their line-up consists mostly of entry-level groupsets until a couple of years ago they brought their Advent X onto the market.
This is a very budget friendly and durable 10 -speed wide range drivetrain. For less than 150$ you can have a shifter, cassette and clutch mech that is used by some EWS pro racers.
TRP (Tektro Racing Products)
Tektro is worldly known as a brake manufacturer, but they have a specific department for their high-end racing products TRP. For MTB they developed with the help of some pro mechanics and riders a specific 12-speed rear mech and shifter: the G-SPEC TR12. If you’re in the market for a high-end alternative to Shimano and SRAM, this can be your answer.
4.Why is it so difficult to buy any groupset?
If you’re in the market for an upgrade, you’ll probably have noticed it’s quite the feat to get your hands on any parts. Cycling supply chains have been disrupted following the massive demand for new bikes and parts due to the ongoing COVID-19 pandemic.
Manufacturers simply can’t keep up with the demand. Covid-19 had quit it’s hand in it with factory shutdowns due to national lockdowns, restricted capacity due to social distancing. But there are even more reasons:
- The prices of raw materials, as in many other industries, such as aluminum, steel, and carbon have been rising continuously for months.
- Transport costs have also risen disproportionately due to a shortage of containers, ships, and to congestion at ports. And who doesn’t remember the grounding of the ever given in the Suez Canal for 6 days, blocking all traffic.
- The bike industry is suffering from ongoing failures in the supply of components. This forces bike brands to seek for similar alternatives.
5.Our FAQ about mountain bike groupsets
How tochoose a mountain bike groupset?
When choosing a new groupset there are couple of factors you need to take in consideration:
- Your riding style
- Your current freehub body – best case scenario you only need to replace your freehub, worst case scenario you’ll need to buy a new wheelset to fit your desired cassette.
- Your budget
- Personal preference
This is a question we can’t answer for you as it is more a matter of personal preference. Some will say a full Shimano groupset, others will say a full SRAM build. Or you can even find a mix of both worlds: precise shifting under load with a Shimano drivetrain, but berakes by SRAM to have more modulation.
Can you use a mountain bike groupset on a road bike?
Technically yes, you can. But there are lot’s of things to take in consideration:
- Bottom bracket and spindle compatibility, most MTB bottom brackets are longer than a road bike bottom bracket and has a different diameter.
- Front derailleur compatibility
- Cassette compatibility – road bikes don’t use a wide range cassette. You’ll mostly be stuck in the higher gears.
Does a mountain bike groupset come with shifters?
If you buy the whole groupset at once, yes of course it does.However if you want to pick and match different accessories from different groupsets together, you need to buy the desired shifter separately.
How hard is it to upgrade mountain bike groupset?
If you do not have the appropriate tools for the job and knowledge, it is impossible to change your groupset. ( you need: a chain whip, cassette tool, correct bottom bracket tool, brake bleed kit, hex keys,…)otherwise it is a pretty straight forward job, but you can always ask help at your local bikeshop if necessary.
Do you need a new hub for wheel when upgrading groupset mountain bike?
This depends, for certain upgrades you will need to change your hubs.
Shimano 8, 9, 10 and 11 speed cassette = HG freehub
SRAM 8, 9, 10 and 11 speed cassette (+ SX eagle and NX Eagle) = HG freehub
Shimano 12 speed cassette = Microspline
SRAM 12 speed (starting from GX)= XD body
Check your freehub/cassette before investing in a new groupset!!
Can you mix different groupsets on your mountain bike?
Yes, you can for as long as you stay in the same ecosystem. All Shimano components starting from Deore and up are compatible with each other. You can have a Deore cassette, XT cranks and a XTR lever without any issues. Same goes for SRAM, starting from SX Eagle, every component is compatible with any other Eagle part.
Of course you can mix and match your brakes and drivetrain.
