Focusing on low weight and smooth power transfer, road groupsets use exotic materials to achieve their goal of a great stiffness-to-weight ratio. The drivetrains will most often be a double or 2x setup, with two chainrings in front and between 8-11 gears in the back. As they roll easier and faster on narrower tyres compared to mountain bikes, road bikes utilise larger chainrings in front and smaller gears in the rear with a narrower range to achieve a smoother change between gears.
What most sets road groupsets apart from their MTB counterparts are the shifters. With drop handlebars, the shifters have become integrated into the brake levers for convenient placement and shifting whilst riding. How these shifters work varies from brand to brand, each having their preferred mechanism, which is explained below.
Most road groupsets still feature caliper brakes, but there’s been a strong movement towards disc brakes as they offer more powerful braking, better modulation and little change in performance in adverse weather conditions. There is also a move towards electronic groupsets, with Shimano, SRAM and Campagnolo all offering electronic options. However, the vast majority are still cable operated, mechanical groupsets.
The most popular offerings from Shimano are the Tiagra (4700), 105 (5800) and Ultegra (R8000). SRAM’s most popular groupsets are the Rival and Force, with Apex taking up their entry into road and RED being their flagship groupset. For Campagnolo, their most sought after groups are Potenza and Chorus, while their range tops off with their Record and Super Record groupsets.
Shimano is synonymous with road cycling, developing and introducing some of the most integral technologies in cycling today, many of which we take for granted. Shimano was the first to introduce the sort of dual control levers we see today. It is called Shimano Total Integration or STI for short. It uses the brake lever and a small secondary lever underneath the brake blade to shift up and down the gears. Pushing the large right-hand lever inwards changes the gears up, while the small lever changes down, and vice versa on the left-hand side.
Shimano’s road groupsets range from Claris (R2000) as the entry level road-specific groupset, all the way to the professional Dura Ace (R9100). The 11 speed options begin with 105 (5800), offers most of the top level performance at a more wallet friendly price point, and even the 10 speed Tiagra (4700) is a solid option for the enthusiast cyclists. For near top performance with a small weight gain is the Ultegra (R8000) groupset, following closely to the recently updated Dura Ace (R9100), and sharing much in terms of design and technology.
Di2 totally revolutionized groupset technology to this day, offering super quick and accurate shifting with little-to-no maintenance, and no cable stretch. With competitors following closely behind with their own electronic options, Di2 was the first truly successful electronic drivetrain to hit the market. Only a couple years in, Di2 equipped bikes were winning the Tour de France, a significant landmark for the technology.
The latest versions of Di2 have introduced a new feature to the technology, called Syncro Shift. It uses the right shifter to control both front and rear derailleurs, changing the front derailleur automatically. The point at which the front derailleur shifts is customisable, allowing you to choose when it changes. It simplifies the handlebar but removing the need for the left shifter, while allowing the greater range of a 2x drivetrain to be utilised. All these changes can be made wirelessly via any compatible Bluetooth device.
All Shimano groupsets come with their own rim brakes, and from Tiagra upwards, are offered with disc brake options. These hydraulic disc brakes provide greater stopping power and modulation in any weather condition compared to rim brakes.
You wouldn’t think that SRAM has only been making complete road bike groupsets since 2006. Their road drivetrain progress was swift and quickly brought about SRAM's first road victories in 2008, bringing home the win in the Tour of California, Tour of Italy and Tour of Spain.
With their new road groupsets, SRAM takes a different approach to Shimano’s STI shifters and Campagnolo’s Ergopower™ shifters. Instead of using two shifter arms for each hand to control the gears, SRAM’s DoubleTap® uses a single arm under the brake lever to shift. To choose a higher gear in the rear, a short push is needed (one tap) is needed, while for a lower gear you need to push the shifter arms further, which actuates the second tap, shifting into a lower gear. This is revered for the front gears.
Taking a cue from their MTB line-up, SRAM offers all but their RED® groupsets in both 1x and 2x variants. This is to cater to hybrid bikes, gravel and adventure, and cyclocross race bikes that prefer a simpler 1x setup, where smaller gaps in gear ratios aren’t as much of a factor. SRAM are the only of the three big groupset manufacturers to offer three different kinds of braking options: cable-operated rim brakes, hydraulic rim brakes and hydraulic disc brakes.
In response to the electronic Shimano Di2 groupset, SRAM took it to the next level with their RED® eTap wireless electronic groupset. By avoiding the need of cables or wires, eTap simplifies drivetrain setup, while still allowing for fast and precise shifts. SRAM’s RED® eTap shifters work similarly to a sequential car’s gearbox, with the right-hand lever shifting up and the left-hand shifting down. Both shifter arms are used in order to shift the front derailleur.
Campagnolo road groupsets match style and performance with a long history of road racing. Since 1933, Campagnolo has been a name associated with road racing at the highest levels. They have a huge focus on high tech materials, carbon fibre in particular, and they’re not shy about showing it off, with raw carbon components adorning their top groupsets.
As Campagnolo is very much a racing focused brand and don’t offer a budget level groupset. Instead, they start in the middle, at the level where riders are looking for race capable components. Campagnolo is a heart over head brand, that has passion running through the components.
All Campagnolo groupsets now come in 2x11 speed setups with the recent reintroduction of their entry level Centaur groupset. Above Centaur is the Potenza groupset, followed by the Chorus groupset, which offers high quality materials like titanium and carbon for weight savings, strength and precision performance.
Above Chorus is the flagship Record groupset. Ready to race, the Record groupset is highlighted with raw carbon fibre adorning most components. And yet, even above Record is Campagnolo’s truly elite groupset: Super Record. This groupset is reserved for only the top racing bikes and the most exclusive machines.
The Electronic Power Shift, or EPS, is Campagnolo’s electronic groupset system. It is found on Chorus EPS, Record EPS and Super Record EPS and uses wires – like Shimano’s Di2 – to actuate the shifts.
Campagnolo have also recently unveiled their first disc brake offerings. They are available with the Potenza groupset, moving up through Chorus to Record and Super Record. This will include both Record EPS and Super Record EPS. Campagnolo was the last to introduce disc brakes into their line up in the form of their DB line and high end H11 line. Their calipers are flat mount and will be made to use either 140mm or 160mm rotors, but will not be interchangeable between the two.
Hybrid groupsets are often a mix between road and mountain bike components. Some are directly taken from mountain biking, like Deore (M6000), SLX (M7000) and XT (M8000), while others find their way from road. The Sora (R3000), Tiagra (4700) and Ultegra (6800) all offer flat handlebar shifters that work perfectly for hybrid bikes and offer the higher gear ratios of road bikes. The more entry level bikes, recreational drivetrains, like Altus (M2000), Acera (M3000) and Alivio (M4000) provide solid performance that doesn’t break the bank, at the expense of greater weight and less technology.
The city/urban specific drivetrains from Shimano are Nexus, Alfine and Metrea. The first two are internal hub drivetrains, housing the gears inside the rear wheel and not needing a derailleur. They range from 3-11 speeds and the Alfine even comes in Di2 form. The Metrea groupset is Shimano's dedicated hybrid 11 speed groupset and even comes with its own disc brake set.
On entry-level hybrids, more basic Shimano drivetrain components can be found in the form of Tourney. These are often not available for sale separately and are not a complete drivetrain on their own.