Your bike's groupset comprises everything that makes it go and stop.
It's important that all these components work together seamlessly. Here's a typical road bike groupset.
The individual components are:
1. The crankset comprises one, two or three chain rings. The chain ring provides the drive to the rear wheel via the chain connecting it to the cassette. The crankset is attached to levers to which the pedals are fastened. The chain rings typically comprises 1, 2 or 3 toothed gears which allow a major gear change. The more teeth, the higher the gear.
2. The rear cassette. The rear cassette has a larger number of cogs (usually 7 to 11) of different sizes and is connected to the rear axle. At any given time, one of the front chain rings is connected to one of the rear cogs via the chain, such that rotating the chain ring using the pedals rotates the rear cog at the same rate.
3. The chain. Connects the front chain ring to the rear cassette. The highest gear is when the largest chain ring is connected to the smallest cassette cog and conversely, the lowest gear is the smallest chain ring to the largest cassette cog.
4. The derailleurs. Attached to the rear axle, the rear derailleur moves the chain from one cassette cog to the next. Attached to the frame near the crankset, the front derailleur moves the chain from one chain ring to the next. The derailleurs can move in either direction, to change gears up or down.
5. The shifters. Attached to the handlebars, the shifters allow the rider, by a simple lever movement, to move the derailleur so that it changes gears. There are two shifter, one on the left side of the handlebar and one on the right. The left shifter controls the front derailleur and the right shifter controls the rear.
6. The brakes. The brakes and the shifters are part of the same assembly. Typically, the brakes are levers that are pulled down towards the handlebars and the shifters are levers that are moved sideways (Shimano) or clicked downwards (Campagnolo). The left brake lever operates the rear brake and the right lever operates the front brake. Always engage the rear brake first when using both brakes.
The groupset is where a lot of the money in a new bike goes.
Japanese company Shimano is the most popular groupset manufacturer with a range of groupsets at different prices.
It’s constantly updating the groupsets too, with the newest features debuting first on its top-end groupset, Dura-Ace, before eventually filtering down through the range.
The more expensive groupsets are lighter and offer smoother gear shifting and superior braking performance.
You also get more gear ratios with the more expensive groupsets, 11-speed on Dura-Ace, Ultegra and 105, down to 8-speed on entry-level Claris. The gear ratios are determined by the number of teeth on each cog of both the chain rings making up the crank set at the front and the cassette attached to the rear axle.
Here is the entire Shimano Road Bike Groupset Range, from the most to the least expensive.
- Shimano Dura-Ace 9150 Di2
- Shimano Dura-Ace 9100
- Shimano Ultegra R8000
- Shimano Ultegra R8050 Di2
- Shimano Ultegra 6870 Di2
- Shimano Ultegra 6800
- Shimano 105 R7000
- Shimano 105 5800
- Shimano Tiagra
- Shimano Sora
- Shimano Claris
The three groupsets marked Di2 use battery-driven electronic shifting, the rest use mechanical shifting. First introduced in 2011, electronic groupsets have proved to be extremely popular, with precise gear changes, long battery life and good durability.
For my money, the best value Shimano groupsets are Shimano 105 R7000 and Shimano Ultegra R8000 in the mechanical shifter range and the Shimano Ultegra R8050 Di2 in the electronic shifter range.
Make your choice based on budget.
There is very little difference in performance between Dura-Ace and Ultegra with the latter being marginally heavier but also more robust and similar considerations apply between Ultegra and 105.
See also Is Cycling the Perfect Exercise?