The groupset - that set of components which includes cranksets, derailleurs, tensioners, cables, levers, and brakes - is the biggest differentiator of a road bicycle after the frame. So much so that many cyclists consider changing the groupset before changing their bicycle in order to gain efficiencies in their performance or improve their riding style.
How do you decide when to change the groupset and what variables should be taken into account when planning to acquire a new one?
These are the variables to consider.
Cassette: Speed vs. Rotation
The smaller the cassette, the harder it is to move. A 25-tooth cassette will be harder to rotate than a 30 or 32 tooth one. However, when a cyclist wants to reach an optimal speed - for example, 18 kilometers per hour on a 6.5% incline - they will need more aerobic capacity to move a 30-tooth cassette, as they will have to increase the number of pedal strokes or revolutions per minute (rpm). Nevertheless, if they use the 25-tooth cassette, they will need more leg strength to move that gear ratio.
The set of cogs, also known as the "cassette," depends on the type of groupset. A lower-end groupset will have eight to nine speeds, while higher-end ones can go up to 11 speeds. This component can be interchanged without replacing the entire groupset, especially when the cyclist wants to find more comfortable or suitable gear ratios for their riding style. However, it is necessary to check compatibility with other components before doing so.
Riding style vs. Topography
There is no right or wrong riding style. It depends on the preferences and capabilities of each cyclist. In short, those who can rotate the pedals at 80, 90, or more rpm will use lower gear ratios, while those with more leg strength will use lower gear ratios to maintain the same speed. However, the topography of the routes to be ridden must also be taken into account. Cyclists who prefer less hilly routes can opt for smaller cassettes and larger chainrings. On the other hand, if they seek climbs and prolonged ascents, it is more advisable to have a smaller inner chainring and cogs with more teeth in the rear.
When to change the groupset?
There are two reasons to replace the drivetrain group: changes in the cyclist's riding style or simply due to wear and tear. In the first case, as the athlete trains or improves their condition, they may prefer a groupset with different capabilities. Conversely, if they discover that their riding style aligns with other gear ratios, they may also consider different options for cassettes, chainrings, or a complete drivetrain group. In short, the goal is to feel comfortable when riding.
How to evaluate a groupset?
The main variable that concerns cyclists is weight. The lighter the groupset, the more expensive it will be because it requires the use of different materials. The number of speeds it offers is also important.