What are today’s mountain bikes without their groupsets? Frankly, not much. Mountain bike groupsets have seen a lot of updation and innovation in the past few years. Nowadays we hear things such as 500% gear range and four-piston hydraulic brakes – we’ve clearly come very far. So much so, that understanding mountain bike groupsets these days can be a little intimidating and confusing.
WHAT IS A GROUPSET?
A groupset is a collection of bike components designed to work together to drive and stop your bike. It usually refers to the gears and brakes on your bike.
Groupsets are categorized by manufacturers and also by name into different levels of price and performance to form hierarchies. This makes buying replacement parts easier and also is a way of identifying the level of performance a bike is aimed at.
Groupset components are often not made by bicycle manufacturers themselves. Instead, they are made by groupset specific manufacturers such as Shimano, and SRAM each of who have driven the development of the mountain biking scene for many decades.
COMPONENTS IN A GROUPSET
- Bottom bracket
A majority of the mountain bikes these days feature a “trigger shift” style shifter (although SRAM still produce a twist-grip shifter). The trigger shifters normally use two levers that can be either pushed or pulled to change to an easier or harder gear.
Shimano shifters have a thumb pushed trigger to change to an easier gear (downshift). Behind the downshift is a secondary lever that can either be pulled with the index finger or pushed with the thumb to return to a harder gear (upshift).
SRAM on the other hand utilizes gear shifters that incorporate two thumb pushed triggers in a similar orientation. Both Shimano and SRAM allow multiple downshifts (usually 3-4 gears) dependent on how far you push the forward trigger.
A chainset is comprised of a chainring or 2/3 chainrings, crank arms, and a bottom bracket axle. You’ll notice that most XC bikes and lower end bikes will have upto 2/3 chainrings up front. Higher end trail,enduro and downhill bikes will most likely have a single/one-by chain ring.
There are a vast range of chainring sizes to choose from, with the size being dictated by how many teeth the ring comprises. To put it simply, the greater number of teeth equates to harder gearing but more speed, whilst smaller chainring sizes will provide easier gearing for more efficient climbing.
Crank arm lengths also vary in accordance with the rider’s height. The most common length is at 175mm used on most M-L frame sizes. Shorter (165 or 170mm cranks) are easier to pedal, better for riders with shorter legs, and also reduce the likelihood of rock strikes on technical terrain.
A cassette is a collection of multiple sprockets/cogs. For mountain bikes, the number of cogs and cog sizes are the most important factors. Situated on the rear wheel hub, the cassette is responsible for the smooth gear changes that make up the majority of everyday riding on the trails.
The number of cogs can be anywhere from 8 to 12 depending on the groupset. The advantage of having more cogs is that you have less ‘jumps’ in the spread of gears, wider range, and less cadence fluctuation.
4. FRONT/REAR DERAILLEUR
Modern derailleurs have changed too much since their conception many decades back. They have, however, become a lot more reliable, efficient, smoother, durable, and crisper in terms of shift quality. Most mountain bike derailleurs have been designed with very strong springs to aid chain retention and minimize chain bounce.
While you do still come across two-by mountain bikes these days it’s primarily Shimano who caters to these bikes. Sram now only produces front derailleurs for its most basic groupsets such as the X4, X5, and the X7.
Brakes, especially on MTB’s are given less importance than they actually deserve. MTB brakes are primarily of two types rim and disc. Further within disc brakes are the two classifications of mechanical and hydraulic disc brakes.
Shimano does offer hydraulic disc brake options for all of its MTB specific groupsets. Sram on the other hand, despite producing their own brakes, tends to label them dependent on the intended use of discipline – rather than by groupset name.
6. BOTTOM BRACKET
The bottom bracket is a little complicated to understand – think of it as a large axle through which the pedals are connected, and around which they rotate. A crankset won’t get you very far without bearings to spin on. These bearings are pressed or threaded into the mountain bike’s bottom bracket shell (refer to the picture below).
This seemingly unimportant component is the bearing through which there is a connection between the crankset and the bike’s frame. Quality in this vital junction is paramount for efficient power transfer. A good-quality unit, if correctly installed, should provide years of trouble-free riding, but bearings can and do wear out over time.
Yep, chains are groupset specific too – they’re just as important as the other components of a groupset.
The type of chain your bike needs is linked to the number of cogs in the cassette. The greater the number of cogs, the narrower the space is between the cogs (all cassettes effectively have to be the same width universally). Chain links will alter in width, with a 7-speed chain being significantly wider than a 12-speed chain.
The more expensive chains are smoother, more durable, have anti-rust coatings, and save weight with hollow links and pins. With that in mind, chains are the first part of a drivetrain to wear out, so it’s often best to invest in a mid-level chain (unless your racing competitively).
Most chains are cross-brand compatible as long as the speeds (no. of gears) match. To avoid confusion – always match your cassette and chain brands.
TOP GROUPSET MANUFACTURERS
Whilst we know that it’s primarily Shimano, and SRAM that are dominating the groupset market, it’s worth mentioning that there are other smaller players in this market.
1. SHIMANO MTB GROUPSETS
Japanese giants, Shimano are the market leaders in all cycling categories, Shimano has the biggest range of mountain-specific groupsets too.
Most of Shimano’s groupsets are designed to work in unison with each other, making it possible to mix and match componentry, although for optimal performance it’s best to keep within the groupset.
SHIMANO GROUPSET HIERARCHY
- DEORE XT
- XTR Di2
* The Shimano Zee and Saint groupsets are Enduro and Gravity specific groupsets that you’re unlikely to see on most common mountain bikes.
2. SRAM MTB GROUPSETS
Sram is the newer player in the groupset market but they’ve proven themselves very capable and have taken an edge in the mountain biking segment in most markets.
Sram, in many ways, is the more progressive company in the mountain bike sector with having first introduced 2x and then 1x drivetrains to the mainstream mountain bike world. SRAM is fast leaning towards the 1x (one-by) drivetrains on nearly all of its intermediate to premium groupset options.
SRAM GROUPSET HIERARCHY
- NX Eagle
- GX Eagle
- X01 Eagle/AXS
- XX1 Eagle/AXS
WHAT IS ELECTRONIC SHIFTING?
You’ve probably heard of electronic shifting these days. Electronic shifting essentially works via wires attached to the shifters and derailleurs that transfer a signal, or via wireless technology similar to Bluetooth or ANT+ devices.
The benefits of electronic shifting are the precise shifting, the lack of deviation from the set adjustment, easier shifting at the lever, decreased cable routing difficulty, programmable shifting, and downloadable information on shifting habits and efficiency.
The downside of electronic shifting is the system breaking down if batteries are not charged, high prices, and generally heavier weight when compared to their mechanical counterparts.
FUN FACT: SRAM’s electronic AXS system is completely wireless whereas, Shimano’s electronic Di2 groupsets do have wired cables.
WHAT ARE CLUTCH DERAILLEURS?
You might be thinking, “what are clutches doing on bicycles?” Well yes, they’ve come here too. Unlike in the automotive industry, clutches on bicycles do not need to be activated before every gear change.
Here the point of the clutch mechanism is to tension the chain to keep it in place when riding over rough and uneven ground, eliminating or at least decreasing ‘chain slap’ – when the chain lashes the chainstay, potentially causing damage and risking a “dropped chain”.
Shimano clutched derailleur have an on/off switch next to thier upper pulley to activate the clutch or release it so that it works like a regular mech.
Sram on the other hand has an “always-on” clutch that cannot be turned off.
WHAT AM I PAYING FOR?
If you’ve been browsing, you’ve probably noticed that there are significant price jumps between basic and progressively more high end groupsets.
Is a jump from the Sram NX to the Shimano Deore XT worth it?
“Strong, Light. Cheap. Pick two” – Keith Bontranger
As prices soar, so do the material tolerances that the components are built to. This is most evident in the quality of the gear shifts.
Gear shift quality on higher tier groupsets is often smoother, more immediate and more precise than their entry-level offerings. This allows them to perform better even under load.
Lighter components are always better – you have better control of your bike, its more snappy (responsive) and climbs and jumps easier.
At the lower end expect more components to be made from basic materials such as pressed steel or to feature less refined manufacturing processes. Higher tier groupsets tend to be lighter, often by using more exotic materials such as carbon fibre or titanium.
This is something that almost every mountain biker doesn’t mind paying more for. Durability in a mountain bike groupset is super crucial.
It’s often the mid-level groupsets such as the SLX or GX that have components that, with the right care, can last a long time.
Higher tier groups such as the XTR or XX1 are often considered ‘race day’ components, as the lightweight nature of the parts will see them wear out at an alarmingly fast rate.
Think of the costs of maintaining your groupset, especially your chain and cassette – both regularly replaced items.
Almost all of the innovation and R&D goes into the top flight groupsets which then trickle down over the years through to the lower groupsets. This means that even low-end groupsets are now packed with features that were unthinkable of a few years ago. Choose what suits your requirements the best.
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WHAT I LOVE ABOUT CYCLING
I’m an avid mountain biker and I like riding fast and flowy singletrack. As I keep riding, I continuously work on honing my riding skills. I like to ride whenever possible, especially with friends. I also like to influence folk into getting to ride more often.
Working on bicycles has also been a keen interest of mine for quite some time.
DISCIPLINE: Mountain biking and Road biking
CURRENT BIKE: Merida One Twenty 9.600 & Specialized Allez Elite DSW
DREAM BIKE: Santa Cruz 5010