The clear market leader, Shimano has the largest range of road specific groupsets and is a favorite with professional teams too. Shimano pioneered the STI (Shimano Total Integration) lever, which is the most commonly used lever today. The ingenious system allows the user to change gears up or down and brake with one hand. The right-hand lever controls the rear derailleur and front brake (brake orientation can change based on country), while the left-hand lever controls the front derailleur and rear brake. The STI lever allows for multiple shifts and means never having to move your hand position to slow down or change gears. To operate, the brake lever swings inwards to pull the derailleur in one direction, with a smaller shift lever sitting behind the brake lever which releases the cable for the derailleur to go the opposite direction.
Most of Shimano's groupsets are designed to work together (as long as they share the same number of gears), making it possible to mix componentry, although for optimal performance it's best to keep uniformity.
Below is a brief description Shimano's groupsets.
- Claris: Claris is Shimano's entry-level groupset best suited to recreational or fitness bikes. It has an 8-speed cassette and comes in either a double or triple crankset providing a multitude of gearing options. The triple is available as a 50 / 39 / 30 tooth crankset, while the double is available in a traditional 50/34 tooth compact set-up or a smaller 46 / 34 option. Claris uses simple and intuitive dual control levers with gear indicators so you'll always know what gear you're in without having to check the cassette at back. Claris also has an option for flat bar road bikes, a purpose-built shift lever known as 'RAPIDFIRE Plus'.
- Sora: Sora is similar to Claris but adds an extra gear with a 9-speed cassette and is also available in a double or triple crankset. Sora has a different aesthetic to Claris and features a four-arm crank instead of five. Sora also offers 'RAPIDFIRE Plus' shift levers for use on flat bar road bikes.
- Tiagra: Tiagra appears on many entry-level bikes priced just over the AU$1,000 mark and gets another gear with a 10-speed cassette. While still seen on recreational bikes, Tiagra is common on entry-level road bikes or off-road adventure bikes thanks to its combination of durability and performance. The crankset is also available in a double and triple, with up to a 34T sprocket available on the rear cassette providing a huge range of gears. In order to accommodate the larger sprocket, Tiagra's rear derailleur comes in a long and short cage option. The options for cranksets increases by one, with a 'mid-compact' 52/36 gear option available, which has proven popular in upper-tier groupsets.
- 105: 105 is considered Shimano's first step into the performance orientated groupset market and is the most popular groupset on road bikes. Aimed at the entry to the intermediate level road rider, 105 is durable, reliable and features much of the technology found on the more expensive Ultegra and Dura-Ace. 105 has 11 cogs on the cassette, the same as Ultegra and Dura-Ace, so at this point, you can change and swap componentry with a minimal decrease in performance. Interestingly, there are three different crankset options for 105; a four-arm double crankset, a five-arm double crankset and a five arm triple crankset. 105 is the first groupset to provide a traditional 53/39 crankset, while still offering a mid-compact (52/36T) and traditional compact (50/34T) set-up. A 32T sprocket is the largest 105 can accommodate, and like Tiagra, the rear derailleur comes in a long and short cage option.
- Ultegra: Ultegra is for intermediate to high-level road riders with almost identical features to Dura-Ace, albeit with a weight penalty. Many professional teams will use Ultegra cassettes and chains mixed with Dura-Ace components to save money in the offseason. Ultegra is only available in a double crankset with various combinations; 53/39, 50/34, 52/36 and 46/36.
- Ultegra Di2: Ultegra also comes in an electronic version known as 'Di2'. Unlike the mechanical version which requires cables to change gears, Di2 uses motor-driven mechanics at the front and rear derailleur to provide a crisp perfect shift, every time. The Di2 version is slightly heavier than mechanical (about 80g) but can be activated at two different locations thanks to satellite shifters, which are commonly found on the inside of the drops for sprinting, or top of the handlebars for climbing.
- Dura-Ace: Dura-Ace is the gold standard of groupsets from the Japanese company. The groupset uses a mixture of carbon fiber, titanium, and high-grade alloys to create precise shifting and unmatched reliability. 17 teams at the 2015 Tour de France used Shimano Dura-Ace as their groupset of choice, highlighting its status in the professional ranks. Dura-Ace shift levers have a shorter lever stroke and more ergonomic design to improve rider feel and comfort. A longer derailleur cage is used to accommodate a 30T sprocket on the new Dura-Ace, where previously a 28T sprocket was the largest available. The derailleur cage borrows technology from the MTB world, sitting lower and more central to improve aerodynamics and reduce damage in the event of a fall.
- Dura-Ace Di2: The latest edition of Dura-Ace Di2 gets a significant upgrade from the current wired-only (and Windows PC-only) setup with wireless communication, for both ANT ‘Private’ (works with ANT+) and Bluetooth connectivity. The upgrade, in association with Shimano’s soon-to-be-released ‘E-Tube Project’ app, will allow for complete customization of shift settings, shift button purpose, shift speed, and wireless firmware updates. 'Syncro' shifting is another new feature that provides an almost automatic response in front shifting based on your choice of rear gear. Riders using previous 11-speed Shimano Di2 groupsets will be happy to know they can upgrade their system to feature synchro shifting.
Shimano Road Component Release Schedule